Hot Weather Vegetable Transplanting Tips

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Brassica seedlings ready for transplanting

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 centers 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 rutabaga 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 fertilizer 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 fertilizers. Unlike synthetic fertilizers, which release nutrients when dissolved in water, organic fertilizers undergo biological processes that require both moisture and time. Bits of organic fertilizer 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 fertilizing, 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 fertilizer 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.

Shade cover for seedlings
Shade cover for seedlings

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
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

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Comments

 
"Another great subject not covered often enough. Thank you. Funny you should mention Texans using window screening. I've got an old, slightly bent up sliding-glass-door screen hovering over my tomato transplants, with an additional two layers of shade cloth on top. Plus, I bought a roll of that screening and cut it up, then sewed it up to make a small trashcan like structure to put over my squash seedlings to protect them from squash bugs that are still around. My question to you is about my Table King Acorn Squash seedlings (actually, lack of). I bought fresh seed this past July (few weeks ago) including broccoli, cauliflower, melons, and winter and summer squash. All the seeds have popped up except for the acorn squash. I've got my seed starting kit outside in my courtyard to take advantage of the warmth (more like blistering heat) and sunshine (3 hours of direct, very bright shade rest of day). Might the acorn squash not be coming up because it's too hot for it??? The zucchini squash came up fine, though. Or might it just be chance that I planted two duds (though I normally have 100% sprouting rate for reasonably fresh seed packets)?"
Sylvia B. on Friday 5 August 2011
"Thanks for the good tutoring on growing a fall garden! This is my first fall garden, so I'm a newbie to all the fall vegies we can grow here in Huntsville, Alabama. I set out plants of brussel sprouts, broccoli and cabbage in late August. I made row cover supports out of two wire coat hangers twisted together at the top, cut in half at the bottom - so the four little wire legs support sheer curtain fabric I had left over from a craft project. It seems to work pretty good - holding the rows shade cover about a foot over the little plants. My question is - how long do I leave the shade covers over the plants? Just a few days? or until our hot weather cools off in late September? Thanks for your help, Barbara. I remember hearing you speak at our botanical garden a few years ago. You're a great speaker - it was a real treat to hear you. Warm Regards - Becky"
Becky Harris on Sunday 28 August 2011
"respected Sir I want to cultivate crops ( any crop) under the hot climate (48 degree to 50 degree cen:) can you suggest me the crop name? Noor hussain chandio, Sindh Pakistan"
Noor Hussain on Thursday 23 August 2012
"Kind Sir (Mr. Noor Hussain), in case you do not get a quick response from a more experienced gardener than I am, I thought I would give you a little something to start with. Where I live (Texas), we do not get quite as hot as you do, but we get close. Last year, for 90 days, our high temperatures for those three months were between 38 C (100 F) and 43 C (110 F). And I don't believe it rained once during that time, so we had to supply water for our gardens to keep them alive. Between all my fellow gardeners and me, I noticed that the plants that seemed to survive the heat without trouble were: Cowpeas (Vigna unguiculata, variety Pink-eye Purple Hull) Okra (Abelmoschus esculentus, variety Clemson Spineless) Watermelon (Citrullus lanatus, variety Charleston Gray) The watermelon vine grew but did not produce any melons until the weather cooled in early fall. The okra and cowpeas greatly slowed their production, but still kept producing a little bit during the high heat. I have also heard that sweet potatoes (Ipomoea batatas) do well in the hot summer sun, but I have not tried them yet. I do not know what kind of soil you are working with, but we have heavy clay here, and I amend my soil with about one inch of compost each year by tilling it in. Good soil (and watering, of course) can mean the difference between fried and growing plants. One other option you might consider is having two growing seasons with a break during the hottest part of summer. If you can grow quick plants that are ready in 50-70 days, then maybe you can have one growing season in the Spring and another one in the Fall. This way you can avoid the heat of summer and the freezing temperatures of winter. Though I am not familiar with the kind of seasonal weather you deal with. Good luck, and happy planting!"
Sylvia B. on Friday 24 August 2012
"I had not looked at this thread in a while, and I just want to thank the thoughtful contributors here. It is so nice to be part of such a generous gardening community."
Barbara Pleasant on Sunday 10 May 2015

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