As part of our strategy to entice pollinators and other beneficial insects into our garden, we plant selected flowers among the vegetables. 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 – IP065” It’s 99c for the download unless you are a subscriber, or if the cost is beyond your budget. Oregon State Extension has a 40 page year 2000 version online.
We plant Sweet Alyssum with our spring broccoli and cabbage to attract insects that prey on aphids. This works very well. We plant one Alyssum plant per 8 broccoli or cabbage plants in the center-line of the bed, between the two rows of brassicas. We sow it in the greenhouse in early March, around the time we sow replacement broccoli and cabbage, and transplant in mid April when we do the gap-filling, replacing any brassica casualties, 2 or 3 weeks after transplanting the brassicas. We have to explain carefully to our helpers not to weed them out, or smother them with mulch when we move the garlic mulch over to top up the brassica mulch.
As you’ll see in some of the photos, we do also grow some repellent flowers (nasturtiums, french marigolds) and some trap crop flowers (cleome for harlequin bugs) but I’m not going to talk about those today.
Plants with small flat open flowers, like alyssum, dill, yarrow, buckwheat, sunflowers, cosmos can attract ladybugs, lacewings, aphid parasites, damsel bugs, braconid wasps, rove beetles, syrphid flies, and spined soldier beetles. This is a rather loose and general statement. you can read the ATTRA 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.
At the end of April we sow several plug flats of different flowers to plant out in Insectary Circles at the ends of our raised beds. We include borage, dill, calendula, cosmos, sunflowers zinnias and tithonia in that sowing, and hope to plant them out in mid-late May, after the big push to get all our tender transplanted crops out. We used to sow earlier, but we find ourselves too busy to get them transplanted at the right stage of growth, so it’s better for us to hold off and sow later.
We choose beds where the crop will be in place for a long stretch of time, hopefully to the frost date. This includes tomatoes, eggplant, okra, chard, leeks. Because our focus is on food crops and we are always too busy, we have evolved a method that uses little time and reduces the chance of things going wrong. As mentioned above, we get a lot of help in the garden from visitors and people who help out for half a day a week, so we need to make the flowers obvious to prevent over-zealous weeding. The main way we do this is to take old plastic buckets and saw hoops from them. We set the hoops in the soil and plant he flowers very close together inside the hoops. This marks them out as something special. And it really works fine to have the flowers just 2 or 3 inches apart.
Insectary flower planting day is ideally one when rain is expected at night, as otherwise it’s a fussy job to tour all the circles with a watering can every day. We take a wheelbarrow and set the flats leaning out the sides like wings. Some kinds of watering cans can be carried on wheelbarrow handles. that helps. The hoops can also go on the wheelbarrow handles. Then we work our way along the driveway, finding suitable beds. We dig with a trowel to make a circle big enough to set the hoop in, and pile any extra soil inside. Then we plant a selection from our flats, water and move on.
After the driveway, we work along the center path between the east beds and the west beds and then back along the east side, where there is a path. We hope to find a suitable spot every 25 feet or so. if it doesn’t rain, we do hand-water daily until each circle has had a good soaking from night-time sprinklers or rain.
We haven’t made a scientific study of whether these flowers do attract more beneficial insects than we had previously, but we do enjoy seeing the flowers, and I firmly believe that diversity of species helps the ecosystem.