flowers to attract beneficial insects – Sustainable Market Farming

Flowers Against Aphids – The Research Continues

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September-sown Borage flowering in our hoophouse in January. Photo Pam Dawling

It’s late November as I write this. Starting last fall (2021) we sowed a range of flowers to attract beneficial insects, to plant in our hoophouse in hopes of reducing the early spring aphids. Aphids can get out of control in early spring in our greenhouse and hoophouse, as they become active before their native predators, such as ladybugs, emerge from hibernation. In January we get bad aphids on the lettuce and, of the flowers we planted to attract beneficials, borage was the only one flowering. It was not enough. We did three sprays of soapy water at 5 day intervals to kill the aphids. We also have a particular problem in our hoophouse and in our greenhouse on the eggplant, pepper and tomato transplants from mid-April to mid- to late- May depending when we manage to get them under control.

Young eggplant struggling against lots of aphids.
Photo Pam Dawling

Most flowers in our trials were annuals, and they flowered and died. We still have four yarrow plants and one bushy shungiku. Shungiku is Glebionis coronaria, (formerly called Chrysanthemum coronarium, Ismelia coronaria, Xanmthophthalmum coronarium, or Pinardia coronaria), and commonly called Crown Daisy. Most chrysanthemums are perennial with poisonous leaves, but shungiku is an annual. Our plant seems not to know this.

September-sown shungiku (chrysanthemum greens) in January.
Photo Pam Dawling

Shungiku is the eastern Japanese name for the edible chrysanthemum, also known as “garland chrysanthemum” or “chop suey greens” in English. It is known as “Kikuna” in western Japan, “tong hao” in Chinese, ssukgat in Korean and cải cúc or tần ô in Vietnamese. There are various colors of flowers. Ours are yellow, not banded with other colors. We bought seed from Small House Farm. Bevin Cohen says it does attract bees, butterflies and predatory insects, and would probably do well in the winter hoophouse, and could be provoked into bolting early in the spring.

After our research and trials, we decided it isn’t worthwhile growing the annuals, as they didn’t flower when we needed them (except this shungiku!). We might try borage again, as it was quick to flower last year, and other people have done well with borage. Ours died. We also decided (as recommended by a reader) to leave some overwintered brassicas to flower. We are starting to find bolting mizuna, so that may be perfect.

Bolting mizuna in our hoophouse
Photo Pam Dawling

Two of the four yarrow plants have flowers (in November) and we will keep them. Having perennials seems a good way to get flowers in early spring. These plants were too young to flower last spring. We still have some seeds of the perennial phacelia, so we could try that again, although perhaps it isn’t cold-hardy enough.

Anti-aphid yarrow flowering in our hoophouse in late November, 13 months after sowing. Photo Pam Dawling

If you want to read the trials and research that led us to this point, see two posts from February 2022: More on Insectary Flowers. It was too cold for predators in early February, even with enticing flowers. Ladybugs showed up in late February and we had borage flowers for them, but no other flowers. We had sowed at the very beginning of September and the very end of October. After that, we started more flowers in our greenhouse on February 1. We noticed that plants in pots dry out very fast in the hoophouse, and they have to be hand-watered, as the drip tape doesn’t do it. It’s probably better to get the flowers in the ground in the hoophouse and greenhouse as soon as they are big enough.

Earlier in February, I posted Growing flowers to attract aphid predators in early spring

I listed aphid predatory insects such as ladybugs, lacewings, aphid parasites, damsel bugs, braconid wasps, rove beetles, syrphid flies, and spined soldier beetles, as are attracted to plants with small flat open flowers, like alyssum, dill, yarrow, buckwheat, sunflowers, and cosmos.

On a big scale this is known as Farmscaping, and you can read about it in a publication from ATTRA; Farmscaping to Enhance Biological Control . You can use this publication to make a specific plan to tackle particular pests. Ladybugs are a good general help because they eat the eggs of many different pest species.

A ladybug on the leaf stem of a sunflower planted to attract beneficials. Photo Pam Dawling

Organic Integrated Pest Management involves tackling pest problems one step at a time with ecologically-based practices, starting with actions chosen to reduce the chances of the pest ever getting a grip on your crops. You can find various listings of steps online and in print. They are all in basic agreement – start with prevention, follow with avoidance, and finish with pest-killing if needed. I recommend the ATTRA Organic IPM Field Guide. Each of the 22 pages is a poster, complete with good photos and concise clear info.

eOrganic has many articles on Insect Management in Organic Farming Systems that explain ways to tackle pest problems with ecologically-based practices, starting with actions chosen to reduce the chances of the pest ever getting a grip on your crops.

A pepper leaf with tiny aphids.
photo Pam Dawling

That post describes the lifecycle of aphids, starting in spring with eggs hatching into wingless females that give birth via parthenogenesis to more females. Within a week, one female can produce 100 clones, which can repeat the process at the age of one week. This continues until adverse weather or predators trigger production of a generation of winged female aphids that moves to new plants. Later in summer male aphids are born and females lay fertilized eggs that overwinter on host plants, to hatch the following spring.

There is a chart in the post, giving details of the flowers we chose, where we found the seed, and which months we decided to plant them in.

Our first sowing, in September, was of borage and shungiku (Chrysanthemum greens) only. We thought having some flowering plants in large pots would enable us to move them to the trouble spots, but plants in pots dry out too fast. The borage flowered with pompom-like clusters, much more compact than spring outdoor borage does.

Anti-aphid flowers yarrow in pots in January (October sown)
Photo Pam Dawling

The second sowing, in late October, included Meadowfoam, Tidy Tips, Phacelia and Yarrow. Those plants were still small at the beginning of February. No flowers, no help against January lettuce aphids.

The third sowing was February 1, and included borage, shungiku, Meadowfoam, Phacelia, Tidy Tips and yarrow.

The September-sown borage and shungiku both had trouble with cold temperatures during January – three non-consecutive nights at 10F (-12C). Some of each got cold-damaged.

By February, no beneficial insects had been seen on the borage flowers, and no aphids had been killed as a result.

Shungiku in November with a bee.
Pam Dawling

Shungiku with spider, in November. Pam Dawling

Shungiku with a fly in November. Pam Dawling

This looks like a leaf-footed bug on the shungiku in November. Not good news to have this pest around! Pam Dawling

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The background to these 2022 trials included a lot of research. In July 2021 I posted Controlling Aphids in Early Spring

Climate change is making the problem worse: for every 1degree Celsius rise in average temperature (about 2 F degrees), aphids become active two weeks earlier.

Organic Integrated Pest Management

I have a blog post about our organic integrated pest management, a 7 step method of pest management which starts with actions least harmful to the ecosystem, only employing biological controls such as botanical sprays and selective pesticides if necessary after all other steps have been insufficient.

Pepper plant with aphids and ants farming them.
Photo Pam Dawling

Applying these principles to dealing with early spring aphids

Prevent infestation Control ants (which farm aphids for their sweet excretions). Try repellents, or trap crops of nasturtiums.
Cover or protect physically with fine mesh netting.
Provide habitat for natural enemies. Plant for a continuous supply of insect-attracting blooms, that flower early in the year and attract predators such as ladybugs, lacewings, syrphid flies (hoverflies), damsel bugs, big-eyed bugs, and spiders. Grow early flowers with pollen and nectar they can use as alternative foods. Sow seed in fall for earliest bloom.
Monitor crops at least once a week
Introduce natural enemies: We do have an aphid parasite in the hoophouse as we do find mummies, but not enough to control an aphid outbreak in spring. Parasitic wasps for aphids include Aphidus colemani from Arbico Organics; Aphidus ervi from Arbico; a predatory gall-midge, Aphidoletes aphidomyza, (cost $125 including shipping per week, perhaps $375 total); Green Lacewings (more affordable); Ladybugs, notorious for flying away.
Hand pick and kill. Handpicking aphids is likely impossible, so blast them off the plants with a water jet from a hose.
Use biological controls. Failing success with the methods above, a soap spray can be effective, although aphid predators will also be harmed. We use 3 Tablespoons (15 ml) per gallon (3.8 l) of biodegradable Murphy’s Oil Soap, in a sequence of 3 sprayings 5 days apart.

Also see that post for details about Tidy Tips (Layia platyglossa), a spring flowering wild annual in the aster (sunflower) family; Meadowfoam (Limnanthes douglasii), a fast-growing bushy annual commonly known as poached egg plant and Douglas’ Meadowfoam; Baby blue eyes (Nemophila menziesii), a low spreading, shrub-like annual; Borage, a warm-season annual, taking only about 8 weeks to flower from sowing; Sweet Alyssum, a small annual; Shungiku, described above. We considered, but did not plant two biennials: Dill and Angelica, as they sound quite large. The perennials we chose, are also large (30” tall, or much more, and might need staking), but the advantages of having permanent working plants won us over. Yarrow is hardy to zone 5. Common Yarrow (with flowers that range from white to red) is hardy down to zone 3. It attracts an array of beneficial insects. Phacelia is particularly useful in early spring if it has overwintered as it is an early pollen source for bees coming out of hibernation. Sow in the fall for early spring blooms But it winter-kills at approximately 18˚F (-8˚C), and I think that’s what happened to ours. We also considered Fennel, Foeniculum vulgare (common fennel) but it blooms from mid-summer to frost. Too late and too tall for our goal of attracting spring aphid predators in the hoophouse. Coyote bush, (Baccharis pilularis), also called chaparral broom, is a native shrub related to sunflowers, that sounds way too much of a space hog. And Dandelions – I just couldn’t bring myself to risk planted this sturdy weed in the hoophouse!

That post also includes details of natural enemies you can buy, and how to make a soap spray if none of those efforts work. Also there you will find the approach we decided on as the Best Options for our Hoophouse and Greenhouse in April and May

November photo of shungiku flowering in our hoophouse alongside Yukina Savoy, senposai and Hakurei turnips. Pam Dawling

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Way back in July 2016, I posted Insectary Flowers to Attract Beneficial Insects

This post covers insectary flowers outdoors and in, at various times of year. At the end of April we sow several plug flats of different flowers to plant out in Insectary Circles at the ends of our outdoor raised beds.

See my July 2017 Mother Earth News post Insectaries: Grow Flowers to Attract Beneficial Insects In late May or early June, we transplant IPM

flowers in our outdoor Insectary Circles in the vegetable garden to attract pollinators and pest predators. We use circles cut from plastic buckets to surround these clusters of flowers so that inexperienced helpers don’t pull them out as weeds. We use a combination of sunflowers, dill, borage, cosmos, calendula, tithonia (Mexican sunflowers), zinnias.

Cindy Conner suggested leaving parsley and celery plants to overwinter and flower early.

Hoophouse Winter Schedule Tweaks and Improvements

I’m always on the lookout for ways to pack more crops in, get higher yields, reduce or at least spread the workload. All while nurturing healthy soil and organic food that people enjoy.

Tweaking the Salt Wash-Down Dates

Using a lawn sprinkler to wash down the salt build up in our hoophouse. Photo Pam Dawling

I wrote about Preparing your Hoophouse for Fall and Winter on September 28. I belatedly realized that in my hurry to publish the post I let some out-of-date info slip in. We don’t do our fall salt wash-down in November any more – we prefer early October, while it is still warm enough for the plants to be improved by extra water, rather than drowned and miserable. We have switched from two days in the spring to three, as we think two days wasn’t quite enough water to get all the salt back deep in the soil profile. We had ambitions of doing three days in the fall as well, but I can tell you now, from experience, that we can fit in two days but no more.

I’ve described how we broadfork and rake all the beds in the fall, and the amount I can do in one day (along with all the other tasks) is 1/3 of a 96ft x 4ft (29m x1.2m) bed. That human limitation, and the logistics of crop rotation and planting dates, leaves a small window between preparing the first three beds to get planted (9/6-10/6), and the remaining four (10/10-10/24). It really doesn’t work well to broadfork and rake saturated soil! It’s better to have a few days for the water to soak in. So, we are satisfied with two days of salt wash-down in fall, for the time being.

Catch Crops

Mid-October photo of September-sown tatsoi and August-sown Tokyo bekana. Fast-growing crops make good use of small windows of time.
Photo Pam Dawling

Last fall I noticed that some areas of some of our beds were idle between being prepped and planting dates in November and December. I hate to waste prime real estate like hoophouse bed space, So this year when we planned our bed layout, we herded all the little late sowings into one bed with the intention of finding some fast-growing crops to put in that space first. We also managed a more rational layout in each bed, planting the various crops in chronological order from the east end to the west.

Next, I researched what we might grow ahead of the main crop. There are some unknowns here. We have numbers of days to maturity for crops in ideal conditions (nice warm spring temperatures), but we are heading into colder temperatures and shorter days. So it might not work out as we hope. However, given our fondness for salad mixes, anything we have to pull up immature will still be eaten and enjoyed!

Salad Mix freshly harvested.
Photo Pam Dawling

The bed in question was all ready to plant on September 30. The areas I could see for catch crops included 11/9 “filler” spinach and filler lettuce, 11/15 tatsoi #2, 12/7 lettuce mix #2, 12/18 mustard salad mix, and 12/20 radish #5.

I decided to put the 16ft (5m) of areas for November 9-15 sowings (39-45 days to go) into 45day Tokyo bekana and the 18ft (5.5m) of areas for sowings after December 7 (79 days available at that point) into 60day Cylindra beets. The Tokyo bekana came up very quickly, and I expect it will be destined for salad greens, which will be very useful as our outdoor lettuce is waning and we’ve just had a patchy frost (early for here) – the colder weather will slow crops down.

The beets have still not come up 9 days later, and the soil is 60F (15.5C). I’ll check again tomorrow. 10 days should be long enough with soil at that temperature. My niggling worry is that the salt wash-down has drowned the seeds. See Root Crops in August. If they are not up at 10 days, I think I will hoe the area and resow with something quicker – perhaps tatsoi (45 days). I was disregarding tatsoi because it will bolt in January. Umm, but this is a catch crop, that we’ll need to pull up in early December – January isn’t even on its calendar!

Carrots out! Cress in!

Belle Isle Upland Cress from Southern Exposure Seed Exchange

Last winter we grew a small patch of carrots because one of the crew really wanted to try them in the hoophouse. I wasn’t a fan because carrots are so slow-growing and provide only one harvest (usually). But I am a fan of democracy and participation, so we grew carrots. We could have harvested them sooner than we did and planted something else (in my opinion), but there they sat all winter.

Oh yes, about that “usually”: you can eat carrot tops and I have used finely chopped carrot leaves as a garnish. A major brand of crackers has carrot tops as one the herbs in their Herb Crackers. Read the small print!

This fall, as we planned our crops, I said I’d prefer not to grow carrots again, but I was out-voted, and hence we sowed carrots. Now those crew members have left, and I gave the evil eye to the carrots. I’d just read an interesting article about nutrient-dense vegetables, and learned that The 5 Most Nutrient-Dense Vegetables Based on Science are watercress, Chinese (Napa) cabbage, Swiss chard, beet greens, and spinach. We’re growing all the others, but no watercress. For the next-best thing, I wanted to try land cress/Upland Cress in our winter hoophouse. So I hoed off the little carrots and sowed Creasy Greens Upland Cress and Belle Isle Upland Cress from Southern Exposure. They take 50 days to maturity (in spring) and I note:

“The yellow blossoms help nourish ladybugs, syrphids, and other beneficial insects”

So I plan to let some flower in spring for the beneficial insects.

Creasy Greens Upland Cress from Southern Exposure Seed Exchange

Flowers for beneficial insects

Last year, one of our trials was a collection of annual flowers to attract more pollinators into the hoophouse. None of the ones we tried seemed to do much, except for one shingiku (chrysanthemum greens) which is still flowering! Readers suggested I’d do better to just let some winter brassicas flower instead of growing special flowers. So upland cress might become part of our solution for that! We’re also growing a perennial, yarrow, to attract beneficials.

Shungiku chrysanthemum greens.
Photo Small House Farm

The other hoophouse tweaks on my list are more for spring and summer, so I’ll leave those for another post.

Growing flowers to attract aphid predators in early spring

Borage flowering in our hoophouse in January, among the lettuces. Photo Pam Dawling

Last July, when sheltering indoors from the heat, planning next winter and spring’s hoophouse crops, I researched and wrote up Controlling Aphids in Early Spring

I also have a post (another July information-gathering project!) about Insectary Flowers to Attract Beneficial Insects outdoors and in, at various times of year. At the end of April we sow several plug flats of different flowers to plant out in Insectary Circles at the ends of our outdoor raised beds. We hope to find a similar approach that will work earlier in the year for hoophouse and greenhouse aphids.

Ladybugs of Maine
Poster from the Lost Ladybug Project

Aphid predatory insects such as ladybugs, lacewings, aphid parasites, damsel bugs, braconid wasps, rove beetles, syrphid flies, and spined soldier beetles are attracted to plants with small flat open flowers, like alyssum, dill, yarrow, buckwheat, sunflowers, and cosmos. This is a rather loose and general statement. On a big scale this is known as Farmscaping, and you can read about it in a publication from ATTRA; Farmscaping to Enhance Biological Control . You can use this publication to make a specific plan to tackle particular pests. Ladybugs are a good general help because they eat the eggs of many different pest species. Organic Integrated Pest Management from ATTRA gives wider information about managing pests organically.

Ladybugs of South Dakota
Lost Ladybug Project

eOrganic has many articles on Insect Management in Organic Farming Systems, that explain ways to tackle pest problems with ecologically-based practices, starting with actions chosen to reduce the chances of the pest ever getting a grip on your crops.

Aphids can get out of control in early spring in our greenhouse and hoophouse, as they become active before their native predators, such as ladybugs, emerge from hibernation. We have a particular problem in our hoophouse and in our greenhouse on the eggplant, pepper and tomato transplants from mid-April to mid- to late-May depending when we manage to get them under control. We are implementing our plan that we made in the summer.

Insectary flowers against aphids

Meanwhile in January we got bad aphids on the lettuce and, of our flowers to attract beneficials, borage was the only one flowering. It was not enough. We did three sprays of soapy water at 5 day intervals to kill the aphids.

Pepper plant with aphids. Photo Pam Dawling

There are many kinds of aphids. The lifecycle of aphids starts in spring with eggs hatching into wingless females that give birth via parthenogenesis to more females. Within a week, one female can produce 100 clones, which can repeat the process at the age of one week. This continues until adverse weather or predators trigger production of a generation of winged female aphids that moves to new plants. Later in summer male aphids are born and females lay fertilized eggs that overwinter on host plants, to hatch the following spring.

This week, I want to give a progress report on the flowers we are growing. The chart gives details of the ones we chose, where we found the seed, and which months we decided to plant them in.

The first planting, in September, was of borage and shungiku (Chrysanthemum greens) only. We hoped these would give us early flowers to start the program. Those plants became big enough to transplant in the ground and in 8” (20 cm) pots. We thought having some in large pots would enable us to move them to the trouble spots.

What I have noticed is that plants in pots dry out very quickly in both the hoophouse and greenhouse! The shungiku have looked close to flowering several times, and the accidentally dry conditions should have helped them to panic and bloom, but they haven’t. The borage flowered with pompom-like clusters, much more compact than spring outdoor borage does.

October-sown Meadowfoam plants in our hoophouse in January. Photo Pam Dawling

The second planting, in late October, consisted of Meadowfoam, Tidy Tips, Phacelia and Yarrow. Those plants are still small, as I write this at the beginning of February.

October-sown Phacelia in January. Photo Pam Dawling

They have been potted up from cells to 4” (10 cm) pots, and some are ready for bigger pots. No flowers, no help against January lettuce aphids.

October-sown Tidy Tips(and more phacelia) in our hoophouse in January.
Photo Pam Dawling

The third sowing has just happened, on February 1, and includes borage, shungiku, Meadowfoam, Phacelia, Tidy Tips and yarrow. I forgot to sow alyssum, so that will be a little later.

Slow-growing October-sown yarrow plants in January, using space in the path between lettuce beds. Photo Pam Dawling

The September-sown borage and shungiku both had some troubles with cold temperatures during January. We had a mild December, then a January with three non-consecutive nights at 10F (-12C). In our double-poly hoophouse, we roll out rowcover at night if it threatens to be 8F (-13C) or lower outdoors. That was about 6 times so far, but 10F (-12C) has been our coldest. Some of each of the borage and shungiku got cold-damaged, and some got rowcover-damaged (hasty pulling!)

So far, no beneficials have been seen on the borage flowers, and no aphids have been killed as a result. We’re still hopeful, especially about reducing aphid numbers on the peppers. More progress reports to come!

Flowers Against Aphids! Photo Pam Dawling

Controlling Aphids in Early Spring

Controlling Aphids in Early Spring

Aphids can get out of control in early spring as they become active before their native predators, such as ladybugs, emerge from hibernation. We have a particular problem in our hoophouse and in our greenhouse on the eggplant, pepper and tomato transplants from mid-April to mid- to late-May depending when we manage to get them under control.We’re planning now, so we can be ready next spring.

Climate change is making the problem worse: for every 1degree Celsius rise in average temperature (about 2 F degrees), aphids become active two weeks earlier.

Newly planted insectary circle of flowers to attract beneficial insects.
Photo Pam Dawling

Organic Integrated Pest Management

I have a blog post about our organic integrated pest management, a step-by-step method of pest management which starts with actions least harmful to the ecosystem, only employing biological controls such as botanical sprays and selective pesticides if necessary after all other steps have been insufficient.

I recommend the ATTRA online publication Organic Integrated Pest Management. Each of the 22 pages is a poster, complete with good photos and concise clear info. Extension.org has an article on Organic Integrated Pest Management that explains how to tackle pest problems one step at a time with ecologically-based practices, starting with actions chosen to reduce the chances of the pest ever getting a grip on your crops.

Steps in Organic Integrated Pest Management:

Prevent infestation: Cultivate a good environment for your crops: healthy soil, sufficient space, nutrients and water, suitable temperature, soil pH. Practice crop rotation to reduce the chances of pests and diseases carrying over from one crop to the next. Clear old crops promptly, so they don’t act as a breeding ground for the pest. Choose suitable varieties that resist the pests you most expect.
Cover or protect the plants physically from the pests (mulches to stop soil-dwelling pests moving up into your crops, netting, rowcover, planting diverse crops, and even growing trap crops)
Provide habitat for natural enemies and other beneficial insects
Monitor crops regularly at least once a week and identify any pests you see.
Introduce natural enemies of the pest (bacteria, fungi, insect predators or parasites)
Hand pick and kill the pests if the pest population is above the action threshold. Many fruit and root crop plants can take 30% defoliation before any loss of yield. Where the crop is the foliage, this may be too much!
Use biological controls (often derived from natural enemies) if the damage is still economically significant after trying the earlier steps in the process.

Applying these principles to dealing with early spring aphids

1. Prevent infestation If you act before the aphids arrive, you can use a fine mesh netting to keep them off your plants, but monitor to make sure no aphids have got inside the net. Control ants (which farm aphids for their sweet excretions). Reputed repellents that I have not tried: dilute garlic, onion or chilies with water; diatomaceous earth (health hazard from inhaling gritty particles); vegetable oils.

2. Cover or protect physically. You could try trap crops of nasturtiums to draw aphids away from your crop, but how much of your space do you want to devote to nasturtiums, and how do you deal with them then? The same choices as on food crops.

3. Provide habitat for natural enemies. Plant for a continuous supply of insect-attracting blooms, that flower early in the year and attract aphid predators such as ladybugs, lacewings, syrphid flies (hoverflies), damsel bugs, big-eyed bugs, and spiders. Grow some early blooming flowers with pollen and nectar they can use as alternative foods. Sow seed in fall for earliest bloom.

Native annuals are some of the earliest bloomers that attract beneficial insects:

Tidy Tips (Layia platyglossa), a spring flowering wild annual in the aster (sunflower) family. The white tipped yellow daisy like flowers are 2” (5 cm) across. A native of California, it grows up to 2ft (60 cm) tall. The seeds attract birds. Flowers have special value to native bees. Tolerates cold to -5°F (-20°C). Likes full sun. Seed is widely available. To start indoors, sow seeds 6 to 8 weeks prior to planting outside. Do not cover; seeds need light to germinate. Seeds germinate in 8-12 days at 65-70° F (18-21°C). Temperatures above 70°F (21°C) inhibit germination.

Information from Laura Blodgett in the Daily Improvisations blog, Southwest Idaho: Starting Tidy Tips from seed in February was too early. The seeds sprouted within a few days. The plants were sturdy from the start. It was too cold to plant them out, but they had so much growth that they were cramped in their small pots. There were enough warm days in March to harden them off, even though temperatures got down in the mid 30’s F (1-3°C) a few nights.

Meadowfoam (Limnanthes douglasii) commonly known as poached egg plant and Douglas’ meadowfoam. The five-petalled 1” (2.5 cm) flowers have yellow centers and white edges. A fast-growing bushy annual, very attractive to hoverflies, butterflies and bees. Requires insect pollination. It grows 6-12” (15-30 cm) tall and wide. Hardy to zone 2. Germinate below 60°F (16°C) (in fall?). May need light for germination. Easy to transplant, but don’t let it dry out! If spring-sown, may not flower until early summer (too late for aphid control). Temperatures below 55°F (13°C) will hinder flower opening as well as honey bee flight.

Baby blue eyes (Nemophila menziesii) is a low spreading, shrub-like plant with succulent stems and flowers with six curved blue petals. It grows 6-12” (15-31 cm.) high and wide. You can expect baby blue eyes flowers in late winter where temperatures are moderate and the plant blooms until late spring to early summer. Wait until soils warm to nearly 60°F (16°C) to sow seeds. Sow shallowly, about 1/16 inch (2 mm) deep. Baby blue eyes flower will germinate in 7-10 days with cool weather and short days. Baby blue eyes self-seeds readily but does not transplant easily. Butterflies, bees, and other helpful insects use the nectar as food. Pinch the tips of the growth to force bushier plant formation. Once the plant has flowered and seed heads formed, cut them off and dry them in a paper bag. Shake the bag after a week and then pick out the larger pieces of chaff. Transplant carefully 6-8 weeks after sowing. Sow in the fall, (but not frost-hardy? winter hardy in zone 7 and warmer?) then blooms from early spring to mid-summer. Baby blue eyes will die out if too hot in summer. Water frequently, provide shade (without hindering insects!)

Borage attracts many beneficial insects.
Photo Raddysh Acorn

Other annuals:

Borage is a warm-season annual, fast at producing nectar, taking about 8 weeks to flower from sowing. Borage grows 1-3 feet (30-90 cm) tall and wide; it blooms from early summer until the first frost in fall. Borage can be started indoors 6-8 weeks before the last frost. Seeds germinate in 7-10 days. Transplant borage seedlings outdoors after the last spring frost. Be careful when transplanting not to damage the taproot. Seeds can also be sown in the fall and will germinate the following spring.

Sweet Alyssum is a great insectary plant for aphid predators.
Photo Raddysh Acorn

Alyssum is a small plant we have used in broccoli and cabbage beds to attract beneficial insects. Sweet alyssum attracts three main groups of predatory beneficial insects a) Minute pirate bugs (they eat aphids, thrips, mites, psyllids, and insect eggs), b) Parasitic wasps (they lay eggs in aphids, beetles, flies, moths, sawflies, mealy bugs, and scales. The larvae hatch and eat their way out, killing the host. c) Hover flies, aka syrphid flies (the larvae feed on aphids). Alyssum flowers also attract butterflies and bees. Buy Sweet Alyssum, not the ornamental cultivars.

Shungiku, Chrysanthemum Greens, Chopsuey Greens, Glebionis Coronaria, is in the aster family, Asteraceae. It is native to the Mediterranean and East Asia. The plant’s greens are used in many Asian cuisines. Shungiku is easy to grow and the leaves, young shoots and stems can be eaten. Leaves are aromatic, with a strong flavor. Some describe the taste as between celery and carrots. Even the petals and seeds can be eaten. Small House Farm grows this (and sells seed). Bevin says it does attract bees, butterflies and predatory insects. It would probably do well in the winter hoophouse, and could be provoked into bolting early in the spring.

Biennials:

Dill is a biennial umbellifera, often grown as an annual. It is easy to grow, germinating in 10-14 days. It doesn’t transplant easily (although we do it every year without a problem). It does self-seed readily, so to prevent this, cut the seed heads before the seeds turn tan. The leggy plant grows 2-4 ft tall (60-120 cm) and half as wide. Each plant grows only one hollow stem with an umbrella-shaped flower head from mid-summer to fall (too late for spring aphid predators). Dill tolerates cold and heat, but will likely die back to the ground after the first hard freeze. It might not be the easiest to include in a hoophouse.

Angelica is a biennial that can flower in the spring of its second year.

Perennials:

Phacelia is a particularly useful perennial plant in early spring if it has overwintered as it is an early pollen source for bees coming out of hibernation. Sow in the fall for early spring blooms – Phacelia will survive mild frosts to bloom in spring. It winter-kills at approximately 18˚F (-8˚C). The seeds need darkness to germinate, and then the plants like to grow in full sun. Phacelia flowers from 6-8 weeks from spring sowing for a period of 6-8 weeks with lavender blooms that attract syrphid flies, bumblebees, honeybees and native bees, and also aphid predators like hoverflies and parasitic wasps. It can grow 6-40” (8-100 cm) tall, given the chance.

Yarrow is a perennial, hardy to zone 5. Common Yarrow (with flowers that range from white to red) is hardy down to zone 3. It attracts an array of beneficial insects. In addition, the scent of yarrow repels deer and mosquitoes.

Fennel, Foeniculum vulgare (common fennel), is an herbaceous perennial commonly grown as a summer annual. 5-7 ft (1.5-2 m) tall; each stem branches near the top and each branch ends with a flat-topped cluster of small yellow flowers; fennel looks very much like dill but is taller and coarser. Fennel blooms from mid-summer to frost. Too late and too tall for our goal of attracting spring aphid predators in the hoophouse.

Coyote bush, (Baccharis pilularis), also called chaparral broom, is a native shrub related to sunflowers. It may be a low-growing shrub or an erect tall bush, depending upon its growing conditions, and so may not be a good candidate for a potted plant in the hoophouse! It attracts syrphid flies, as well as bees and butterflies, with its abundant winter bloom.

Dandelions. If you decide to trust to weeds to feed your beneficial insects, take care about how much seed they sow!

4. Monitor crops at least once a week

5. Introduce natural enemies: We do have an aphid parasite in the hoophouse as we do find mummies, but not enough to control an aphid outbreak in spring. Parasitic wasps for aphids include

Aphidus colemani eggs hatch into larvae which feed on the nymphs from the inside, the nymph swells and hardens into a leathery, grey or brown colored mummy similarly to effects of Aphelinus abdominalis. Once larvae mature, adult A. colemani wasps chew their way out of the aphid mummy and emerge to seek out aphids. These parasites are a good choice for year-round use (in greenhouses and outdoors) as the short days of winter do not affect them. Optimum Conditions: 70-77°F (21-25°C), 80% relative humidity. Release rates: 500-3,000 per acre, 2-3 times at one week intervals, depending on the extent of infestation. This product controls aphids, especially melon and cotton aphids Aphis gossypii, but also attack green peach aphid Myzus persicae, tobacco aphid Myzus nicotianae and bird cherry-oat aphids Rhopalosiphum padi. Price $243 for three batches of 500, including overnight shipping, from Arbico Organics.

Aphidus ervi will consume all types of larger aphids, especially the potato aphid, Macrosiphum euphorbiae, and the glasshouse potato aphid, Aulacorthum solani. It also parasitizes Myzus persicae var. nicotianae, as well as aphids such as Sitobion sp., Schizaphis sp., Rhodobium sp., Acyrthosiphon pisum and others. Use Aphidius ervi especially when aphid infestations are just beginning, as control will be easier to achieve before the aphid population’s explosion. Aphidius ervi are shipped in a 125 ml bottle that contains at least 250 mummies and adult aphid parasites. The bottle has a ventilated cap for optimum humidity. A sugar-water feeder ring ensures adult survival. Release the emerged adults within 18 hours of receipt. The parasitized aphid swells and hardens into a leathery, grey or brown colored mummy. The first mummies can be seen in the crop approximately 2 weeks after the first introduction. Use at the rate of 1 adult per 20-100 sq ft (1 per 2-9 m²) for preventative use. 250 mummies is sufficient for 5000-25,000 sq ft (460-2300 m²). Dose rate may be increased 5-fold for hot spots. Introduce A. ervi weekly for at least 3 weeks. Cost from Arbico is $101 including shipping each time, $303 likely. Monitor weekly and make further introductions as required. When pruning leaves, check for parasitized aphids (brown mummies) and if present, keep these leaves in the greenhouse until new parasites emerge. Because they fly as soon as they emerge, you need to cover doors and windows with mesh screens.

Another option is a predatory gall-midge, Aphidoletes aphidomyza, the larvae of which hunt and kill aphids. Kills over 60 species of aphids, especially those in greenhouses and hoophouses, including green peach aphid Myzus persicae; and the hemlock woolly adelgid Adelges tsuga. Optimum conditions: 64-77°F (17-25°C) with RH of 70%. Shipped as pupae. The adults hatch within 1-12 days. After hatching, females lay eggs among aphid colonies. The eggs develop into larvae, and seek out adult aphids, injecting a toxin in their legs to paralyze them. Then they bite a hole in their thorax and suck out the body contents. Use 1 predator per 10 sq ft (1 m²), 2-3 predators per 10 sq ft (1 m²) for heavier infestations or 4,500 per acre (0.4 hectare) weekly until infestation subsides. 1000 for a 96x30ft (29×9 m) hoophouse, cost $125 including shipping per week, perhaps $375 total.

Lifecycle of the Green Lacewing
Photo J.K. Clark

Green Lacewing adults feed on nectar, pollen, and aphid honeydew, and the larvae are active predators of soft-bodied insect pests: aphids, thrips, whitefly, leafhoppers, spider mites (especially red mites) and mealybugs. After hatching, green lacewing larvae seek out prey – pest eggs, nymphs or adults. They feed for 2-3 weeks, spin a cocoon, and emerge as adults 10-14 days later. Lacewings have the ability to tolerate wide temperature ranges and work well with most other beneficial insects. Green Lacewing Eggs: Best low-cost biological control for common garden pests. If you want to establish Green Lacewings at the beginning of the season or have a limited infestation, choose the appropriate numbers of eggs for your garden or greenhouse. It takes 3-10 days for larvae to emerge depending on the temperature and other environmental conditions. Repeat applications every 1-2 weeks. Green lacewing eggs are available in loose media or on hanging cards for easy release. Green Lacewing Larvae: Best for immediate treatment of a pest problem. If you have a more severe infestation, buy the larval frames or bottles, which provide the quickest means to control unwanted pests – the larvae arrive ready to feed. Adult Green Lacewings: Best for establishing a population. If you are treating a large area and want to create a stable population, buy adult lacewings. The adults come ready to lay eggs throughout the release area. They do not actively control pests themselves. Cost 1000 eggs on cards $30 each time; 1000 larvae $61 each time; 100 adults $85. All prices include shipping.

Ladybugs. live ladybugs are best used when pest numbers are low, but can be used to fight existing infestations. Ladybugs primarily feed on aphids, but will prey on a variety of other pests including mealybugs, thrips, soft scale, whiteflies and spider mites. Each adult can consume up to 5,000 aphids in a lifetime. The larvae eat 50-60 aphids per day. Optimum Temperatures: 62-88°F (15-31°C). Ladybugs are prone to flying away. Help keep them around and attract native species by planting perennial and annual flowering plants and by avoiding chemical sprays. Create shaded areas or plants with dense canopies to provide alternative habitat when conditions are not ideal. While these methods may not keep all the ladybugs on site, they should help. If you have had issues with ladybug flight, consider using Assassin Bugs or Green Lacewing instead. 4,500 for up to 2,500 sq ft (232 m²). Cost $20/1500 plus Overnight or 2^nd Day Air shipping.

6. Hand pick and kill the pests if the pest population is above the action threshold. Handpicking aphids is likely impossible, so blast them off the plants with a water jet from a hose. This may decrease the population enough for natural predators to begin control.

7. Use biological controls. Failing success with the methods above, a soap spray can be effective, although aphid predators will also be harmed. We use 3 Tablespoons (15 ml) per gallon (3.8 l) of biodegradable Murphy’s Oil Soap, in a sequence of 3 sprayings 5 days apart. The soap needs to hit the aphids to kill them. Soak both sides of the leaves and directly spray any visible pests. Murphy’s Oil Soap is made from lye (potassium hydroxide) or sodium hydroxide, and vegetable oils with 2% of synthetic ingredients including trisodium MGDA, Lauramidopropyl dimethylamine oxide (a non-toxic purifying agent), sodium tallate. Official insecticidal soaps are made from potassium salts of fatty acids (potassium laurate).

Insecticidal soap works in several ways. The soap penetrates insects’ cuticles, which causes their cells to collapse and dry out. Soaps suffocate insects such as scale insects. Soap sprays are also somewhat effective against chiggers, earwigs, fleas, mites, scales, and thrips. They are not effective on chewing insects such as caterpillars and beetles.

You can make your own soap spray if you have some fragrance-free liquid soap. You do not need to include oil. Note that “dish soap” is actually detergent, not a soap at all, so don’t use that. Test your homemade spray on a small part of a plant first and wait 24 hours to see if there is any damage. Look for spotting, wrinkling, or browning of leaves. If you see any trouble, don’t use the spray.

Soap sprays can be potentially damaging to some plants. Crops that are susceptible to damage from soap sprays include cucumbers, squash, melons, beans, and peas.

Neem is a botanical insecticide effective against aphids.

Best Options for our Hoophouse in April and May

Looking at the options for dealing with aphids and choosing those most compatible with pot-grown plants to flower in spring in our greenhouse and hoophouse, these seem our best chances:

· Cultivate a good environment for our crops.
· Monitor crops regularly once a week.
· Grow Meadowfoam from seed in the hoophouse in late October. Hardy to zone 2. Try February too.
· Grow Tidy Tips from seed in the greenhouse in February, pot up and move into the hoophouse just before flowering. Try starting some in late October too. Tolerates cold to -5°F
Grow Sweet Alyssum from seed started in February.
Grow borage form seed started in February. Move pots to hoophouse after April 1.
Grow perennial phacelia started in October and February for future years. Phacelia will survive mild frosts to bloom in spring. Protect from worse than “mild frosts”.
Grow yarrow from seed started in October and February. It is hardy down to zone 3.
Grow Shungiku from seed sown in late September, and provoked into bolting early in spring.
If we want to spend $100+ to deal with a bad infestation, buy 3 units of ladybugs.

Our Organic Integrated Pest Management

French Marigolds and sesame to combat root knot nematodes in our hoophouse.
Photo Pam Dawling

Steps:

Cultivate a good environment for your crops: healthy soil, sufficient space, nutrients and water, suitable temperature, soil pH. Practice crop rotation to reduce the chances of pests and diseases carrying over from one crop to the next. Clear old crops promptly, so they don’t act as a breeding ground for the pest. Choose suitable varieties that resist the pests you most expect.
Cover or protect the plants physically from the pests (mulches to stop soil-dwelling pests moving up into your crops, netting, rowcover, planting diverse crops, and even trap crops)

Young cucumber plant under **insect netting** in June.
Photo Pam Dawling

Provide habitat for natural enemies and other beneficial insects
Monitor crops regularly at least once a week and identify any pests you see.
Introduce natural enemies of the pest (bacteria, fungi, insect predators or parasites)
Hand pick (or trap) and kill the pests if the pest population is above the action threshold. Many fruit and root crop plants can take 30% defoliation before any loss of yield. Where the crop is the foliage, this may be too much!
Use biological controls (often derived from natural enemies) if the damage is still economically significant after trying the earlier steps in the process.

I recommend the ATTRA online publication Organic Integrated Pest Management.

Each of the 22 pages is a poster, complete with good photos and concise clear info.

Our motion sensor sprinkler and the outer layer of our fence around the sweet potato patch at the end of May. The inner fence was installed later.
Photo Pam Dawling

One of our biggest garden pests is the deer, which are especially fond of sweet potatoes. We use motion-sensor water sprayers initially or in years when the deer pressure is low. For worse years we install an electric fence with a solar-powered charger. Last year our electric fence didn’t keep the deer out, so this year we have a double layered fence to make sure.

Broccoli bed with alyssum to attract aphid predators.
Photo Pam Dawling

At the other end of the size scale are aphids. We plant sweet alyssum in our beds of broccoli and cabbage to attract insects that will eat aphids. We sow about 200 plugs for 1500 row feet (450 m) of brassicas planted as two rows in a bed, and pop one alyssum plug in the bed centers every 4ft of bed or about one alyssum per 4 plants. We transplant these the same day that we replace any casualty broccoli and cabbage plants.

Nasturtiums planted in with squash to deter pests. Does it work?
Photo Pam Dawling

We transplant some bush nasturtiums in with our first plantings of cucumber and summer squash. They are said to repel some cucurbit pests such as squash bugs., but I can’t vouch for that. Radishes in cucumber or squash rows are said to repel cucumber beetles and squash bugs. I haven’t tried that. There are a lot of companion planting ideas out there, but most have no scientific evidence for effectiveness.

An insectary circle in early June. The flowers will attract beneficial insects.
Photo Pam Dawling

In late May or early June, we transplant some flowers in our garden to attract pollinators and pest predators. We use circles cut from plastic buckets to surround these clusters of flowers so that inexperienced helpers don’t pull them out as weeds. We use a combination of sunflowers, dill, borage, cosmos, calendula, tithonia (Mexican sunflowers), zinnias.

Sunflower bee and bug.
Photo by Bridget Aleshire

We also sow sunflowers in our bean beds at each succession. These attract birds and pollinators, while also acting as landmarks for our harvest progress.

In our hoophouse we have been tackling nematodes for several years. This year we have planted the nematode areas in French marigolds and sesame (apparently particularly good in deterring root knot nematodes, the type we have.) Some other nematode areas have been planted with Iron and Clay cowpeas. Unfortunately we now have an aphid infestation on the cowpeas! We are trying blasting the aphids off the plants with a strong stream of water from a hose. Later in the summer we will solarize some of the nematode areas.