Growing High-Yielding Sweet Potatoes

Healthy sweet potato plants. A few insect bites won’t hurt!
Photo Kathryn Simmons

Growing High-Yielding Sweet Potatoes

In May I gave information on planting sweet potatoes. Hopefully that went well for you, and by now you have a large patch of healthy green vines. Let’s keep it that way! Here I will tell you about what the growing plants need, and the pests, disease and afflictions to avoid.

Read more

I have a Sweet Potato slideshow. I have lot of other posts on sweet potatoes (mostly about propagating our own slips, or about harvesting). Click to see the links in last month’s post

The ATTRA publication Sweetpotato: Organic Production is a good introduction.

Oklahoma State University Extension Sweet Potato Production is a clear concise publication (although it’s not organic).

Sweet potato development

This paragraph was included in Planting Sweet Potatoes, and I’m repeating it here, as a good reality check on what you can expect.

Regardless of how early in the season you plant them out, they will not make flowers earlier, or start making tubers sooner. Both flower and tuber initiation are triggered by day length. Each variety has its own internal clock. Most varieties take 90–110 days from planting out to reach a good size, if the weather is warm enough.

The first month or so after transplanting is the root development stage. Roots can go 8’ (2.4 m) deep in 40 days. Don’t be alarmed at the lack of above-ground action. The second month or so is the vine growth stage. The roots begin to store starch and sugar close to the stem base. During the last month of growth for that variety (3rd or 4th month), the potatoes develop. Make sure you dig them up before the soil temperature gets down to 55˚F (13˚C) – the week of the average first fall frost is about right.

Growing sweet potatoes – Three Ws: water, warmth, weed-free
  1. Water
  • The critical time to maintain sufficient moisture is after transplanting for at least the first 20-40 days while roots are developing. By now, most growers will be beyond this most-important watering period. But if it’s less than 40 days since you planted them out, keep the soil moist. Use your fingers to test the soil for dampness.
  • Once they are established, sweet potato plants are fairly drought-tolerant. But if you want high yields, they’ll need water once a week, either from the sky, or provided by you. Note that if you are using plastic mulch, rain won’t go through it, so I hope you installed drip irrigation below the plastic. If not, lay it on top, right beside the plants. Aim to provide an inch (2.5 cm) of water per week.
  1. Warmth
  • Sweet potatoes need warmth! Heat determines success; the number of days from planting does not.
  • Provided the weather is warm enough, most varieties take 90–110 days from planting out to reach a good size.
  • You can gain warmth in a cold climate, by planting inside a hoophouse or low tunnel covered in clear plastic. Ventilate in hot weather.
  • Growing Degree Days (heat units) are a tool for measuring accumulated heat, but you don’t need to calculate GDDs to get a good crop!
  • Early varieties take 1200 GDDs to grow a good crop.
  • To calculate GDDs, take the day’s high temperature (max) and the day’s low temperature (min) and add them together. Divide by 2 and subtract the base temperature of 55F. (Apologies to the rest of the world – I only know this method using Fahrenheit, but I’m sure you can find out how to do the calculations in Celsius). There are phone apps that will do the calculation for you.
  • Example: For a daytime max of 90F, and a night-time min of 70F, you get 25 GDDs – just about perfect for sweet potatoes. 90+70=160. 160/2=80. 80-55=25. At 25 GDDs a day, you theoretically only need about 48 days to get a crop. There are some other limits to daily plant growth – the likely minimum for a decent crop is about 76 days.
  • In a plastic tunnel, you can get 20 GDDs a day or more, rather than the 5 you might get outdoors.

    Water, warmth and no weeds – all that growing sweet potatoes need.
    Photo Nina Gentle
  1. Weed-free
  • Cultivate to remove weeds until the vines cover the ground, after which very little weeding will be needed.
  • If you have plastic mulch, walk through pulling weeds, and drop them on the plastic to cook. If you are growing on bare soil, hoe while the weeds are small, and pull if the weeds and the vines get ahead of you.
  • Weeding is generally not onerous because the sweet potato vines cover the ground within 6 weeks of planting and smother any newly emerging weeds.
Our motion sensor sprinkler and the outer layer of our fence around the sweet potato patch at the end of May.
Photo Pam Dawling
Solar electric fence controller for our sweet potato patch.
Photo Wren Vile
Pest mammals
  • Deer eat sweet potato plants at all stages, including digging out the roots in the fall. Dogs, fences and guns are the three most effective methods of deer control. The plants can be covered with row cover or plastic net for the growing season. Motion-sensor sprayers work well if maintained.
  • Rabbits eat the foliage. Plant the slips on black plastic to hold back weeds, then put wire hoops over the rows and cover with row cover for 3–4 weeks while the plants are young. Even after the plants are large rabbits can cause substantial losses.
  • Groundhogs dig and eat the roots. They can be trapped with baits of fruit. What’s for dinner?
  • Pocket Gophers search out sweet potatoes to eat. Their mounds may be hidden under the foliage and the plants may survive as they only eat the larger roots, leaving no crop.
  • Voles move in from grassy areas to live under the mulch and feed as fast as the roots form. They eat the roots from the top down leaving the outer shell in the soil where they have feasted. Cats are the best control.
  • Rats love the roots. Cats or dogs are the best methods of control.
  • Field Mice build nests under black plastic and eat the roots emerging from the ground.
Why not eat some sweet potato leaves as summer greens?
Photo Nina Gentle
Human “pests” of sweet potatoes

 You can eat sweet potato leaves yourself and it takes several meals to reduce yields of the tubers. Some researchers working in Vietnam, discovered that harvesting 25%, 50%, 75% or 100% of the vines every 15, 20, or 30 days (ignoring the information about the season of the year and the varieties) gave the sort of results you might expect. Harvesting tops every 20 days gave highest yields of greens. Harvesting 50% of the greens each time gave highest total yields of greens. Harvesting not more than 25% or 50% of the greens each time gave the highest eventual tuber yields, after 120 days. Researchers in Tanzania came up with the clear information that harvesting three times at one month intervals gave the highest greens production, but the tuber yield was affected tremendously. Harvesting tops twice in a growing period proved the best in leaf production as well as root yields. So, clip 25-50% of the tops of each plant up to twice in one summer, and you’ll still get a good yield of roots.

Also see the University of Arkansas Extension Nutritional and Medicinal Qualities of Sweetpotato Tops and Leaves. This publication explains how to plant slips 2” (5 cm) apart, specifically for greens (vine tips) and harvest 6 times between the end of April and the end of October.

 Insect pests of sweet potatoes

See North Carolina State University, Pests of Sweetpotato  for photos, drawings and details.

Although there are many insect pests that feed on sweet potato vines and leaves, most do very little damage, and hunting them down is not justified.

Healthy sweet potato patch, with some deer nibbling and weeds..
Photo Wren Vile
Pests that feed on foliage
  • Sweet potato flea beetles – Tiny black/bronze oval beetles (1.6 mm long), with reddish-yellow legs, and ridged wing covers; make small shot-holes in leaves or grooves in the upper surface of the leaves. Damaged areas turn brown and die. See below about larvae.
  • Sweet potato weevil adults and larvae do feed on the foliage, but mostly go for the roots (see below).
  • Caterpillars of three kinds:
    • Southern armyworms – Gray-black larvae up to 36 mm long with green or pink tints; pale longitudinal stripes and pairs of triangular spots along the back; pale yellow heads with bright red-brown marks. They feed on leaves and tips of vines, and congregate around the bases of plants during the middle of the day.
    • Sweet potato hornworms – First instar: white with a black horn; later instars (up to 90 mm long): green or brown with black diagonal lines down each side and a black horn, with a green or brown head with black stripes. They defoliate plants and often hide under leaves near the bases of plants.
    • Yellow-striped armyworms – Pale gray-black caterpillars up to 45 mm long, with orange-yellow stripes along the sides and pairs of triangular spots on the back of most segments; brown heads with black markings and a white inverted V. They feed similarly to southern armyworms.
  • Potato leafhoppers – Wedge-shaped insects up to 3 mm long; green bodies with yellow to dark green spots. They usually jump rather than fly. They suck sap from the underside of leaves causing yellowing of leaf tips and margins.
  • Fruit or vinegar flies – Small yellowish red-eyed flies about 3 mm long. They hover around overripe or decaying produce. They may be found with their small creamy maggots in cracks in sweet potatoes.
  • Tortoise beetle adults and larvae – Long-oval shaped gold beetles, up to 8 mm long, with various black or red markings on their flattened, shell-like bodies. The larvae have dull yellow, brown, or green bodies up to 12 mm long and black heads, legs, spots, and spines. Long spines on the abdomen hold excrement. Adults and larvae chew the leaves riddling them with holes.
  • Spider mites – Tiny reddish or pale spider-like arthropods that feed on the underside of leaves. Heavily infested plants develop a yellowish, bronzed or burned appearance.
Pests that feed underground on tubers and side roots
  • Sweet potato flea beetle larvae – Thin white, cylindrical larvae, up to 5 mm long, with 3 pairs of legs near their heads. They make shallow, winding tunnels on the surface of sweet potato roots and sweet potatoes. The tunnels darken, split, and leave scars.
  • Sweet potato weevil adults and larvae –Snouted beetles 6 mm long with dark-blue wing cases, orange-red legs and thorax, and fat, legless, 9 mm grubby white larvae with pale brown heads. The beetles make small holes over the surface of sweet potatoes mostly at the stem end. The larvae tunnel inside the tubers, leaving frass, which causes the sweet potatoes to taste bitter.
  • White grubs (spring rose beetles) – Dirty white grubs up to 25 mm long with brown heads and 3 pairs of legs near their heads. They leave large, shallow feeding scars on the sweet potatoes.
  • Wireworms – Thin, tough, wire-like larvae with 3 pairs of short legs near their heads and prolegs at the end of the body. They initially create large shallow cavities in sweet potatoes which they later excavate into deep ragged holes. Three species, with colors from yellowish-brown to cream or yellow-grey. Heads are darker, brownish.
  • White-fringed beetle larvae – Yellow-white legless, 12-segmented grubs, up to 13 mm in length, with small, pale heads. They chew into the roots.
Sweet potato souring.
Photo North Carolina Sweet Potato Commission
Afflictions of sweet potatoes (these are not caused by disease organisms) 
  • Round chunky roots, low yield, purple color: Planted too early, too cold.
  • Low yield: Flooded or crusted soil 6-7 weeks after planting? Planted too early?
  • Rough irregular shaped roots: Heavy clay soils or organic matter above 2%.
  • Rattails – thin, tough, tubers: Hot dry weather, insufficient water.
  • Long, slender malformed roots, reduced yield: Potassium deficiency.
  • Souring – Tissue breakdown caused by poor soil aeration, such as flooding.
  • Water blisters – Small whitish bumps around the lenticels (breathing holes): wet soil.
  • Blister – Small raised bumps appearing several months into storage: boron deficiency.
  • Fine hairline cracks: Another sign of boron deficiency.
  • Cracking: Uneven water supply or too much late-season water.
Sweet potato Ring Rot.
Photo North Carolina Sweet Potato Commission
Sweet potato feathery mottle virus.
Photo North Carolina Sweet Potato Commission
Diseases of sweet potatoes (mostly fungal)

 More info and photos: North Carolina State University Diseases of Sweetpotatoes. 

  • Brownish skin patches, worse in wet years: Scurf fungus, Monilochaetes infuscans. More likely if too much compost was used. Stored roots shrivel.
  • Metallic black surface lesions, maybe covering most of the root: black rot fungus, Certocystis fimbriata. Internal decay is not deep, but the fungus may impart a bitter flavor.
  • Sunken brown lesions that may completely encircle the root: ring rot, Pythium
  • Sunken lesions that dry and may fall out: Circular Spot, Sclerotium rolfsii. May taste bitter.
  • Hard, dry, black, sunken spots developing in harvest wounds: Fusarium. Spots may become larger than 2″ (5 cm) diameter, but damage is not deep.
  • Pitting: Soil rot or soil pox fungus in the presence of water stress. Roots will be small and malformed.
  • Streptomyces root rot bacterium causes a similar rot.
  • Fine or coarse irregular cracks, browning of the surface; dry, corky, dark-colored clumps of tissue scattered throughout the flesh, becoming worse if roots are stored warmer than 60°F (16°C): russet-crack/internal cork, feathery mottle virus (yellow feathery patterns of leaves). Do not use as seed stock.
When to harvest sweet potatoes

Unlike white potatoes, which have the annual plant sequence of vegetative growth, flowering and dying back, sweet potato plants would go on growing forever if the weather remained warm enough. Choose when to dig them up, ahead of cold weather. The longer you wait, the bigger the potatoes, but you are gambling with the weather. Usually sweet potatoes are harvested in the week that the first frost typically occurs in your region. I have written plenty already in previous years about harvesting, so I won’t go into it here. See one of the links to those posts, or my slideshow, if you want to know what comes next, or your climate is considerably colder than mine in central Virginia.

Our sweet potatoes next to our sixth sweet corn planting.
Photo Ezra Freeman

Year Round Vegetable Production, speaking events

Here’s my newest slide show, Year Round Vegetable Production, which I presented at the Field School in Johnstown, TN on December 7.  To view full screen, click the diagonal arrows at the bottom right, and to move to the next slide, click the triangle arrow pointing right.

The Field School is a Beginning Farmer program, under the Appalachian RC&D Council. The Field School organizes a monthly series of workshops (November 2017 through August 2018) that provides an overview of small-scale farming in East Tennessee’s mountains and valleys, taught by 20+ farmers and agricultural professionals. It is arranged by the Appalachian RC&D Council, Green Earth Connection, and many area partners with major support from USDA.

As well as my double presentation on Thursday evening, I attended a Q and A brunch on Friday morning and got the chance to meet the new (ish) farmers individually. It was a pleasure to meet such enthusiastic dedicated growers.

My other presentation on Thursday 12/7 was Crop Planning, which you can view by clicking the link.

The school session 2017-18 is already full even though they have expanded to have two tracks (Produce or Small Livestock) in this their third year. Go to their website if you are local and want to be on their waiting list if spots open up. They also sell tickets to the public for some of their workshops.

Beginning farmer training is available in most states, loosely under the USDA, but without a central organization. Do a web search for your state and “beginning farmer training” if you are looking for something like this. Or check out this list on Beginningfarmers.org.


I have been firming up several speaking events in the new year. Here some info on some of those (click the Events tab  or the individual event links for for more details):

The Chesapeake Alliance for Sustainable Agriculture Future Harvest Conference January 11-13, 2018 at College Park, MD.

Ira Wallace (Southern Exposure Seed Exchange), Gabe Brown, Michael Twitty and Craig Beyrouty are giving the meal time addresses.

On Saturday January 13 11.30am -12.30pm I’m presenting

Cold-Hardy Winter Vegetables Why farm in winter? Information includes tables of cold-hardiness; details of four ranges of cold-hardy crops; overwintering crops for spring harvests; scheduling; weather prediction and protection; hoophouse growing; and vegetable storage.

I am also participating with other speakers in a new format Lightning Session Round, 2.15-3.30pm on Saturday, where we each get 10 minutes to tell the audience the top 5 things we want them to know about a certain topic. I’m speaking on Six Steps to Using Graphs to Plan Succession Crops for Continuous Harvests

I will be signing books at the Southern Exposure Seed Exchange booth at points during the conference.


February 7-10, 2018 Pennsylvania Association for Sustainable Agriculture, Farming for the Future Conference, State College, PA https://www.pasafarming.org/events/conference.  I’ll be presenting three workshops:

Storage Vegetables for Off-Season Sales Friday 12.50 – 2.10 pm

Grow crops you can sell during the winter, while allowing yourself some down-time and reprieve from outdoor work. Choose suitable crops, schedules and storage conditions. Understand your weather and basic crop protection. This workshop will provide tables of cold-hardiness and details of four ranges of cold-hardy crops (warm and cool weather crops to harvest and store before very cold weather; crops to keep alive in the ground further into winter, then store; hardy crops to store in the ground and harvest during the winter, and overwinter crops for early spring harvests before the main season). It includes tables of storage conditions needed for different vegetables and suggestions of suitable storage methods, with and without electricity.

Cover Crops for Vegetable Growers Saturday 8.30 – 9.50 am

Using cover crops to feed and improve the soil, smother weeds, and prevent soil erosion. Selecting cover crops to make use of opportunities year round: early spring, summer, fall and going into winter. Fitting cover crops into the schedule of vegetable production while maintaining a healthy crop rotation.

Fall and Winter Hoophouses Saturday Feb 10 12.50-2.10pm

How to grow varied and plentiful winter greens for cooking and salads; turnips, radishes and scallions. How to get continuous harvests and maximize use of this valuable space, including transplanting indoors from outdoors in the fall. The workshop includes tips to help minimize unhealthy levels of nitrates in cold weather with short days. Late winter uses can include growing bare-root transplants for planting outdoors in spring.

There will be handouts for each workshop and book signing


March 9-11 2018, Organic Growers School Spring Conference at UNC-Asheville, Asheville, NC. I’ll be presenting three workshops:

For the Gardener track: Growing Sweet Potatoes from Start to Finish

At this workshop you will learn how to grow your own sweet potato slips; plant them, grow healthy crops and harvest good yields, selecting suitable roots for growing next year’s slips. You will also learn how to cure and store roots for top quality and minimal losses. This workshop will be useful to beginners and experienced growers alike.

For the New Farmer Track: Cover Crops for Vegetable Growers

Using cover crops to feed and improve the soil, smother weeds, and prevent soil erosion. Selecting cover crops to make use of opportunities year round: early spring, summer, fall and going into winter. Fitting cover crops into the schedule of vegetable production while maintaining a healthy crop rotation.

Sustainable Farming Practices 

An introduction to year round vegetable production; crop planning and record-keeping; feeding the soil using crop rotations, cover crops, compost making and organic mulches; production tips on direct sowing and transplanting, crop spacing, succession crop scheduling to ensure continuous harvests, efficient production strategies, season extension, dealing with pests, diseases and weeds; determining crop maturity and harvest methods.


April 12, 2018, 9am to noon,

Louisa Master Gardener Group Tour of Twin Oaks Gardens

Washing tomato seeds, Heritage Harvest Festival, Organic Broadcaster

Wet Roma tomato seeds set to dry with a fan.
Photo Pam Dawling

Last week I wrote about saving tomato seeds and eating the tomatoes too. We left the extracted tomato seed in a bucket to ferment for three days. On Friday I washed the seeds. They look quite unappetizing at first, with a thin layer of mold on the surface of the liquid.

Roma tomato seed ferment on day 3, ready for washing.
Photo Pam Dawling

The process of washing the seeds and pouring off the detritus is almost magical. The fermentation kills some disease spores, and also dissolves the gel that coats the seeds. If you dry tomato seeds without fermenting, they all stick together.

Tomato seed processing: adding water from a hose and stirring the mix.
Photo Pam Dawling

With each successive wash, more of the tomato flesh floats off, along with poor quality seeds. I add water using a hose and stir. Here I’m stirring with a short length of green plastic pipe that was conveniently nearby. When the bucket is about two-thirds full I turn off the hose and stop stirring. Good seed sinks to the bottom of the bucket. When I think it has settled, I pour the liquid along with lumps of tomato flesh into another bucket. This is a safety precaution to ensure I don’t throw away good seed. If I just poured it on the ground I could slip and dump the lot.

Roma tomato seed ferment after first pour.
Photo Pam Dawling

I repeat the wash and pour a few more times. Even after the second pour the seeds are plainly visible.

Roma tomato seed ferment after the second pour.
Photo Pam Dawling

The seeds which float and get poured away are very light and are either very thin or they show a black spot in the center. So it’s counter-productive to try to catch every single seed.Let the useless seeds float away!

Tomato seed extraction after the third pour.
Photo Pam Dawling

After four or five washes the water I pour off is clear, so then I add more water, stir and pour the swirling stuff through a sieve balanced on a bucket.

Tomato seed extraction, fourth wash water. almost clear.
Photo Pam Dawling

In my case I have a small sieve balanced in a bigger one, which sits more safely on the bucket, but has a mesh too big for tomato seeds. This sieve contains seed from 10 gallons of Roma tomatoes.

Roma tomato seeds strained in a sieve.
Photo Pam Dawling

From here, I take the seed sieve indoors and empty it on sturdy paper towels on a tray by a small fan. See the first photo. After a few hours I come by and crumble the clumps of seeds to help even out the drying. For two days I turn the seeds over a few times a day. Once they are dry I put them in a labelled paper bag, and ready the space for the next batch of seeds to dry. Watermelon in this case. I alternate tomato and watermelon seeds, processing one batch of each every week through late July to early September.


Heritage Harvest Festival

I mentioned the Heritage Harvest Festival a few weeks ago. I’m presenting one of the Premium Workshops on Friday, about growing sweet potatoes. See my Events Page for more about this. Pictures of sweet potatoes at this time of year are a monotonous swath of green leaves (now we have got a double electric fence to stop the deer eating the leaves off.) Last year we didn’t do a good job of keeping deer off our sweet potatoes and we got low yields. One of our gardening mantras is “Never make the same mistake two years running!” so you can be sure we are working hard to keep the pesky deer from eating our winter food.

On Saturday September 9, I’ll be out and about at the Festival, and hope to see many old friends and make some new ones.

If you live in North Carolina and can’t make it all the way to Virginia for the Heritage Harvest Festival at Monticello, you could go to the Organic Growers School Harvest Conference that same weekend September 8-9. I’ve been to their Spring Conference several times, but never the Harvest Conference because it’s always the same weekend as the Heritage Harvest Festival.


Photo courtesy of Organic Broadcaster and MOSES

The July/August issue of Organic Broadcaster has been on my desk for a few weeks waiting for time to read it. This newspaper is free online, with a new issue every two months. It covers more aspects of Organic Farming than simply vegetable production. There are good articles about cover crops, including roller-crimping no-till rye. Also an article on weed control for market farmers by Bailey Webster, who interviewed farmers and researchers. Harriet Behar, the senior organic specialist at MOSES, write about the thorny issues of falsely labeled Organic foods: imported livestock feedstuffs, milk from cows with no pasture access and algal oil in Organic milk. Now that 68% of Americans bought organic foods of some kind (Pew), more Organic suppliers are needed to meet the demand (or else the unscrupulous rush in with false labels.) There are further articles about cash flow for farmers, winter bale grazing for cattle, the 2018 Farm Bill, and transferring the farm to new owners.

Now we are getting some rain from Cyclone 10, which might have become Tropical Storm Irma, but now looks less likely to qualify for a name. But, enough rain to want to stay indoors, so maybe I can read for a while.

 

Upcoming events, Growing for Market article, Organic Broadcaster

Harvesting Zephyr yellow squash.
Photo Brittany Lewis

Starting with what’s being harvested now – squash and zucchini are coming in nicely. The hoophouse Gentry yellow squash (chosen for being fast-maturing) is coming in by the bucketload, and the outdoor yellow squash and zucchini have started producing.


I’m off to Burlington, Vermont this weekend, for the Mother Earth News Fair. I’m giving two workshops:

Cold-hardy Winter Vegetables,on Saturday 6/10 at 11 am on the Yanmar Sustainability Stage, immediately followed by book-signing at the Mother Earth News Bookstore noon- 12.30.

Producing Asian Greens on Sunday  6/11 at 3.30 pm on the Heirloom Gardener Stage.

I’m also doing demonstrations of tomato string-weaving at the New Society Publishers booth 2611, near the Mother Earth News Stage (not the Bookstore this time), at 10 – 10.30 am and 3-3.30 pm on Saturday and 10 -10.30 am, 11- 11.30 am and 2- 2.30 pm on Sunday. Check out my Events page to see the pink sparkly tinsel tomato plant models I use!


At the Heritage Harvest Festival near Charlottesville, Virginia, on Friday September 8 (the Premium Workshops before the main Festival), I’m presenting on Growing Sweet Potatoes at 3.30-4.30 in classroom 7, followed by book-signing at the Monticello Bookshop.


The June/July summer issue of Growing for Market magazine is out, and includes my article on Hoophouse soil salt buildup. This is an issue we have been dealing with – we see white deposits on the soil. I did a lot of research and found ways to water the salts back down deep in the soil profile. I also gathered information on how to measure and monitor salinity, and how to understand the test results and their different testing methods and different units of measure. I learned about salt tolerance of different crops, the plant symptoms of excess salinity, and how to prevent the problem in future. This topic is rising in importance as more people use hoophouses with drip irrigation systems. We were blithely ignorant for our first several years of hoophopuse use, as salinity takes a few years to really develop, and there wasn’t much information available.

I’m also looking forward to reading the other articles, especially Summer lettuce lessons from Southern growers by Jesse Frost. There are some great photos of beds covered with hoops and shade-cloth, which show a good system. I always appreciate articles written for southern growers, which can be in short supply.

Daisy Fair in Utah’s zone 5 has written about moveable tunnels with in-ground hydronic heat. So there’s information for cold climates too. Sam Hitchcock Tilton has an article with tips learned from Dutch and Swiss farmers. Robert Hadad advises on careful monitoring of costs of production in order to actually make a living from farming. The flower growing article in this issue is from Debra Prinzing and is about American Flowers Week, a chance to highlight American-grown flowers with some light-hearted fun photos.


The May/June Organic Broadcaster just arrived in its paper format – I’ve had the digital one for a while. Good thing I’ve got that long car ride to Vermont this weekend to catch up on my farming reading!

The front page story this time is about Kansas farmers, Tim and Michael Raile, transitioning thousands of dryland (non-irrigated) acres to Organic steadily over the next 5 or 6 years. Dryland farming focuses on moisture retention. The Railes grow a wheat/corn/
sunflower/milo (grain sorghum)/fallow rotation. They are also trialing some ancient grains.

Organic production in the US is not meeting demand, and organic imports are increasing, including organic soy and feed corn, not just bananas and coffee. More farmers want to produce Organic poultry, eggs, milk and meat. And so they are looking for Organic feed at an affordable price. This is often imported, which raises issues about how Organic Standards vary from one country to another, and the bigger issue of sustainability – not always the same as Organic! Does it really make sense to ship in grains to feed livestock?

Harriet Behar writes about the true meaning of Organic and overall methods of production. It’s not just about following rules on allowed inputs and materials – it’s a whole approach to how we treat the soil, our plants and livestock.

Hannah Philips and Brad Heins share research on how cover crop choices can influence the fatty acids and meat of dairy steers. Jody Padgham writes about CSAs responding to competition and decreasing membership by offering more options on shares and delivery. Gone are the days of “One box, one day, one price” CSAs. Numerous modifications of the basic CSA model have sprung up to better fit the diverse needs of customers (members). Kristen McPhee writes about the Vermont Herb Growers  Cooperative, which buys from various small-scale growers and aggregates orders to larger buyers. Other topics covered include lessons learned from Hawaii’s GMO controversy, paying for end-of-life care without losing your farm, and many short items and classified ads. As always, a newspaper packed with information.


And by the way, we’re also picking blueberries – ah! heaven!

Blueberries.
Photo Marilyn Rayne Squier

Garlic harvest, new barn plans, Mother Earth news post on sweet potatoes

Harvesting garlic by hand, Photo by Marilyn Rayne Squier
Harvesting garlic by hand,
Photo by Marilyn Rayne Squier

We have been harvesting our hardneck garlic for the past week, and the end is not in sight! Back in November, we accidentally planted more than we intended. I can’t remember now if our planting schedule had the numbers wrong, or the planters misunderstood the schedule. Anyway, we intended to increase our ratio of softneck:hardneck, but ended up planting the same amount of softneck garlic as in recent years, and more hardneck than we had grown for at least three years.Those good at math will already realize this means we decreased our ratio of softneck:hardneck!

A word to the wise – don’t plant more than you need! It leads to more weeding, more tending, more harvest than you have use for, and less time to keep up with everything else! Plus you have the heart-rending dilemma of when to cut your losses and how. We were considering tilling in the remaining hardneck garlic before it deteriorated any further, to prevent ourselves from being distracted by the siren-song it was singing, so we could get on with harvesting the softneck before it started to go downhill. Plus of course, garlic is not the only crop! Now we are looking at a mutually beneficial arrangement with some neighbor-friends who don’t have enough garlic – their mistake was not to plant enough! We are offering them a You-Dig arrangement. (Please don’t anyone else contact us hoping to dig some – we can cope with only one set of friends coming and digging!)

Garlic hanging in netting to dry and cure. Photo Marilyn Rayne Squier
Garlic hanging in netting to dry and cure.
Photo Marilyn Rayne Squier

 

 

 

I wrote in Growing for Market magazine my checklist for harvesting, curing, snipping and sorting garlic in August 2015. Here’s the sections on harvest and hanging:

Garlic Harvest Step by Step

  1. Very hard soil can damage the bulbs, so water the night before If the soil is very dry,.
  2. Plan for an average of 15 minutes per 5 gallon bucket for digging up garlic and 15 minutes per bucket for hanging it up.
  3. Bruised bulbs won’t store well, so treat the bulbs like fragile, sun-sensitive eggs. Don’t bang them together, or throw or drop them.
  4. Use digging fork to loosen the bulbs, without stabbing them. Don’t pull on unloosened garlic, as that damages the necks, and they won’t store well.
  5. If there is a lot of soil on the roots, rake the soil out with your fingers
  6. Don’t rub or pick at the skin. To store well, bulbs need several layers of intact skin.
  7. Air above 90F can cook garlic bulbs, sun can scorch them. So don’t leave them out on the beds. Put them gently into buckets or crates angled to shade the bulbs.
  8. No matter how dirty they are, don’t wash the bulbs. They need to dry out, not get wetter. The dirt will dry and fall off later, or if bulbs are not clean enough for market, the soil can be gently brushed off.
  9. Keeping the containers shaded, load them on carts or a truck and take to your barn for drying. It’s important not to leave garlic in plastic buckets for long, because of condensation.

Drying and Curing Garlic Step by Step

  1. We like our garlic arranged in order of harvesting, to make it easier to find dry garlic  when the time comes to trim it. We hang our curing garlic in vertical netting hanging around the walls of our barn. Some growers use horizontal racks, others tie garlic in bunches with string and hang the bunches from the rafters.
  2. We start at knee height, threading one garlic plant in each hole of the netting. (The netting stretches downward with the weight of the garlic. Starting lower would lead to garlic piling up on the floor.) Take a garlic plant, fold over the top quarter or a third of the leaves, and push the leafy part through the netting. The leaves will unfold behind the netting. Leaves shouldn’t poke through to the front.
  3. We work back and forth in rows, filling a 4-6 ft wide strip per person, working upwards.
  4. We continue as high as we can reach before moving to the next section. We make walls covered with garlic, day by day until done. This sequential arrangement simplifies trimming, and makes the best use of the fans, giving the garlic the best chance of drying evenly.
  5. Damaged bulbs are “Farm Use” quality and are set on horizontal racks to dry.
  6. Arrange box fans to blow on the drying garlic. Even in an airy old tobacco barn, fans are essential in our humid climate.
  7. Wait 3-4 weeks, then test some bulbs for dryness by rolling the neck of the garlic between your finger and thumb. It should feel dry, papery, strawy. If many bulbs are slippery, gooey, or damp in any way, delay the trimming until at least 90% of the necks are dry.

Meanwhile, we need a new barn. The one where we cure our garlic is the upstairs floor of an old dairy barn, formerly a tobacco drying barn. I’ve long looked forward to a single-story barn, with no need to haul the garlic upstairs just to haul it down again later. The old barn is seriously riddled with rot and insect chewing. We’d also like a new tool shed, as our old one leans north considerably, and is too small and dark. A small group of us has been meeting sporadically to plan the new barn, and we are divided on whether to go for one story or two. Here’s three questions for other garlic growers reading this:

  1. Do you cure your garlic upstairs in a barn or on the ground floor/first floor?
  2. Do you think one is better than the other in terms of airflow?
  3. Is any extra airflow worth the extra hauling garlic up and down stairs?

We have been drawing floor plans and making scale models, and thinking about storage of tools, seeds and supplies. Does anyone have a good solution for storage of rolls of agricultural fabrics? We roll our shadecloth, rowcover and insect mesh on 5 ft sticks. We’re thinking of slightly inclined shelves (or arms) with adjustable height settings. We want to be able to see what’s what and to keep various different types of fabric separate, rather than in a big heap as at present.

If anyone knows a good book or web resource on storing garden gear, please leave a comment. Using existing ideas beats reinventing the wheel!


My blog post for Mother Earth News Organic Gardening blog, about growing sweet potatoes is out. Our plants this year are looking good. I appreciate how much delicious and nutritious food sweet potatoes provide for so little work!

Sweet potatoes growing on biodegradable mulch. Photo Brittany Lewis
Sweet potatoes growing on biodegradable plastic mulch.
Photo Brittany Lewis

Growing for Market article about sweet potatoes; zipper spiders

GFM_August 2014_coverThe August Growing for Market magazine is out, including my article about growing sweet potatoes. There is (of course!) a whole chapter in my book about sweet potatoes, and I’ve written previously in GfM about harvesting, curing, selecting roots for growing next year’s crop, and storage (September 2007). And also about starting sweet potato slips and planting them in spring (Feb 20007). And the harvest (twice) and starting the slips are covered in my blog too.

This time I wrote about growing the sweet potatoes out in the garden or field: varieties, crop requirements, when to plant, making ridges, using biodegradable plastic mulch, stages of development (roots first, then vines, then potatoes); and pests and diseases.

Also in this GfM is a good article by Joanna and Eric Reuter of Chert Hollow Farm (who I’ve mentioned before., when they decided to drop organic certification). They write about their 12 or so varieties of garlic and how they market them for specific uses such as roasting, eating raw and sauteeing.

The editor, Lynn Byczynski, writes about her son’s wedding and the flower arrangements she made for the big day. Chris Blanchard writes about Gardens of Eagan farm in Minnesota. Once owned and operated by Martin and Atina Diffley, it is now owned by the Minneapolis Wedge Food Co-op. It has expanded and now hosts a few satellite farms which help supply all the broccoli the Wedge needs. Eric Plaksin of Waterpenny Farm (not too far from Twin Oaks), writes about when he broke his foot, and makes suggestions to help other farmers be (somewhat) prepared for adversity, so it’s manageable. And lastly, Gretel Adams writes an inspiring article about growing bulbs and corms for cut flowers.  A good read all round!


And, on a different topic: Does anyone know if zipper spiders eat hornworms?

Zipper spider on tomato plant.  Credit Wren Vile
Zipper spider on tomato plant.
Credit Wren Vile

We get tobacco hornworms on our tomato plants. Outdoors, they usually get parasitized and do little damage. But the mother of the parasites doesn’t fly inside the hoophouse, and in there we sometimes have to handpick the hornworms. These things get big! And are hard to squash! This year we have lots and lots of these zipper spiders, and few hornworms. I never seem to find zipper spiders eating, but they must, because they grow fast. Anyone know what they eat?