Hot Weather Vegetable Transplanting Tips

22 July 2011, written by Barbara Pleasant

Every gardener can grow more veggies by continuing to plant until there is no more time left in the growing season. Previously I've discussed tips for direct-seeding vegetables in hot weather. This time around I’ll concentrate on special techniques for transplanting vegetables when there is too much sun.

First, the seedlings. Many garden centres sell seedlings of fall broccoli and cabbage, but you will need to watch for them. If you’re starting with purchased seedlings, buy them as soon as they become available, and get them planted promptly. In most areas, the time to start seeds of fall broccoli, cabbage and Brussels sprouts has passed or is upon you (check your GrowVeg Garden Planner Plant List), but faster-growing kohlrabi, collards, and kale are worth a try. And, although swede is normally direct-seeded, I often start the seeds indoors and set out the seedlings soon after they sprout. I do the same with lettuce and spinach, which will not germinate in very hot soil.

Growing seedlings indoors is easier in summer than in early spring because Nature provides plenty of light this time of year. A sunny windowsill that doesn’t work as a seed-starting spot in March can become a stellar little nursery area in July! Once the seeds are up and growing, move them to a semi-shaded place outdoors where they can become accustomed to intense sun. The sheltered space under a lawn chair often makes a fine spot for little vegetable plants. Increase their exposure to sun as transplanting day approaches.

Don’t worry that you are growing cool-season seedlings under hot conditions. In my experience, fall broccoli and other cabbage family crops need a period of very warm weather to push their early growth. If you wait until the weather cools down to plant them, it will be too late.

Prepared seedling bed with netting cover — Prepared seedling bed with fine net cover

Basic Bed Renovation

With seedlings waiting in the wings, you will need to prepare their planting space. In most situations, you will be transplanting vegetables into soil that was very recently occupied by spring salad greens, garlic, onions, potatoes or peas. Most gardeners pull out spent plants and compost the remains, though much root tissue remains behind in the soil. To hasten decomposition of old plant parts and replenish soil nutrients, I sprinkle organic fertiliser over the bed before turning and cultivating the soil with a spade or digging fork.

I water the bed thoroughly when I’m finished digging, which is a required step when you use organic fertilisers. Unlike synthetic fertilisers, which release nutrients when dissolved in water, organic fertilisers undergo biological processes that require both moisture and time. Bits of organic fertiliser located right next to seedlings’ roots can cause problems (imagine hundreds of miniscule hot compost piles firing off in the soil like chemical firecrackers), so I wait a day or two after fertilising, digging and watering the renovated bed to move on to the next step.

Most of the big fall vegetables are heavy feeders, so in addition to mixing some organic fertiliser into the bed, I also bury a cache of compost beneath each seedling. In addition to benefiting the soil and the plants, this is great use for compost that’s likely to contain numerous weed seeds, which won’t sprout when buried under a cabbage plant. It’s also tremendously helpful to flood prepared planting holes with water before setting the seedling in place. Insulated from the hot, drying conditions at the surface, this "buried water" is often sufficient to get seedlings off to a strong start.

Protecting Plants with Shade Covers

After seedlings are set out, I highly recommend the use of shade covers or row covers to protect the little plants from excessive sun and/or insect pests. Wedding net (tulle) makes a great summer row cover, or you can make a shade cover by using clothespins to attach a piece of cloth to stakes or other supports. I use both techniques, as well as flowerpot shade covers. After setting out small seedlings that are of little interest to bugs, for example bulb fennel, I simply cover them with small flowerpots for two days after transplanting.

Additionally, I must again suggest using buckwheat as a nurse crop for young seedlings. Whenever I have a renovated bed that I’m not quite ready to plant, I sow buckwheat in rows between where my crop plants will grow. When I’m ready to transplant broccoli or other seedlings, I pull out enough buckwheat plants to make an opening, and use the pulled plants as a surface mulch for the seedlings. Every few days I pull additional buckwheat plants that shade the seedlings, until only a few are left to attract the attention of beneficial insects.

Broccoli seedling with a buckwheat mulch

In some areas, grasshoppers, armyworms and cabbageworms are such serious late summer pests that stronger measures are needed. In Texas, some gardeners use window screening to protect plants from grasshoppers, which will chew through many types of cloth. The screening can be cut and shaped into small cones to place over individual plants, or you can staple screening onto a wood frame to protect an entire bed.

The good news is that pest pressure eases off rather suddenly as nights get longer and cooler, so that many fall vegetables approach maturity with minimal aggravation from bugs. The hardest part of growing a fine fall vegetable garden comes at the beginning, but if you can get your seedlings planted and provide temporary protection from insects and excessive sun, your reward will be tender fall broccoli sweetened by early frosts, and spectacular spinach salads to carry you into winter.

By Barbara Pleasant