Sacramento Digs Gardening: Rescuing a heat-stressed plant

This wilting squash plant doesn't need a rescue -- the wilting is its natural survival mode in heat.
But other plants might need some first aid in a heat wave. (Photos: Kathy Morrison)

It happens to all of us who garden in the heat belt of the Central Valley. The blazing sun finds a plant before you do, and it’s already in trouble when you do find it.

Help! Can it be rescued? Let’s assume so. Here are some ways to figure out the best rescue:

In-ground plants

1. Is it wilting? That's probably how you noticed it was in trouble. First, check the moisture level around the plant. Dig down about 6 inches with a probe or small trowel (avoid the roots if possible) and see if the soil is dry.

If there's dry soil below about the top inch or so, water the plant immediately and adequately so that the little feeder roots can soak up the water. Keep an eye on the plant. If it's pretty new to that spot, you should also give it some shade until it recovers.

A plant flat on top of a tomato cage is a quick

shade solution.

A short tomato cage topped with burlap or even one of those square plastic plant flats is a good makeshift shade structure. Depending on the size of plant, an open umbrella or a piece of shade cloth tied to two stakes also could work. Also, avoid draping fabric on the plant itself; that just adds to its stress.

Important: Don't feed a wilted plant until it fully recovers. There are some liquid concentrate booster products, however, that can be added to that first thorough watering; SuperThrive is one I like for recovery efforts.

Wilting plants with adequately moist soil are just using their natural heat defenses and should perk up again as temperatures drop. Tomatoes and squash plants do this routinely on hot afternoons (see photo at top). Don't water the plant; just keep an eye on it. If it's still wilting in the morning, then water.

If the plant is wilting but the soil is quite wet, you have a serious irrigation problem. Your plant could be drowning. Investigate where all the water is coming from and shut it off asap. You might also dig a tiny trench -- just drag the top of your trowel along the ground -- to pull some of that moisture away from the plant. The plant should recover, as long as the soil is allowed to dry, but keep an eye on it for fungus development. And fix that irrigation source pronto.

2. Is it sunburned? Oh, boy, been there. Tomato leaves in particular can get scorched in heat, but other vegetables do too. If the plant's not otherwise wilting, just give it some shade while the temps are high. (See shade suggestions above.) Don't cut off any burned leaves at first, because they'll protect the plant for a bit. Once daytime temps moderate, you can cut off the dead leaves to make room for new growth.

If the burned plant is a shrub or tree, you might consider whether it's planted in the right spot. Not every "full sun" plant can cope with our heat. Did there used to be more shade in that spot, as from a tree that's since been removed? Watch where the light falls during the course of the day. If it's getting full-bore afternoon sun, the scorched plant could be a candidate for a move this fall when transplanting is easier on you and the plant. Meanwhile, give it some shade.

Container plants

Plants in pots are more susceptible to heat stress because their roots are above ground and vulnerable on all sides. In a prolonged heat wave, they might require watering twice daily.

For a stressed plant, moving it to a shadier area is the first-aid remedy. Then check these situations:

1. Is the soil dried out? Water it first, and watch how it drains. Your plant's roots may have shrunk from the sides of the pot, and any water is traveling straight down the sides and out. Try to loosen the soil a bit, then put the entire pot in a bucket of water to soak until all the air bubbles are gone. Then remove the container from the bucket and keep the plant in a shaded spot to recover.

A larger pot and crumpled newspaper provide insulation
for this potted parsley plant. Some shade would also help.

2. Is the pot too small? The plant may be root-bound, which also causes frequent wilting. Transplant it as soon as possible to a larger container. Meanwhile, water it well and keep it in some shade. You can also temporarily set the pot, plant and all, inside a larger pot and fill the gap with straw or crumpled paper for insulation.

3. Was it recently transplanted? Move it out of the intense sun and baby it some more until new growth appears. You might have to prune it back if it's a large plant that's still adjusting to its new pot.

4. Is it cooked? Unglazed pottery containers and black plastic pots are cheap but are the worst for potted plants in our summers: The roots do get baked. Assuming you already tried the rescues above for a plant in one of these pots and it survived, consider moving it to something else that doesn't get so hot. Or try the pot-inside-a-pot insulation trick. Unglazed pottery also can be buried, halfway or all the way, in the ground as a temporary or even permanent solution to its rapid evaporation.

5. Is it lonely? Container plants do better in heat when several pots are grouped together; they act as mutual insulation. But try the other remedies first.

GENERAL GARDENING

An article about gardening.

Keywords:

plant rescue tomatoes Sacramento trees climate container gardening heat stress gardening vegetables summer garden container plants heat shrubs

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Garden checklist for week of June 14

We'll be back to normal temperatures for mid-June (about 86 degrees) by Thursday. In the meanwhile:

* Let the grass grow longer. Set the mower blades high to reduce stress on your lawn during summer heat. To cut down on evaporation, water your lawn deeply during the early hours of the morning, between 2 and 8 a.m.

* Tie up vines and stake tall plants such as gladiolus and lilies. That gives their heavy flowers some support.

* Dig and divide crowded bulbs after the tops have died down.

* Feed summer flowers with a slow-release fertilizer.

* Mulch, mulch, mulch! This “blanket” keeps moisture in the soil longer and helps your plants cope during hot weather.

* Avoid pot “hot feet.” Place a 1-inch-thick board under container plants sitting on pavement. This little cushion helps insulate them from radiated heat.

* Thin grapes on the vine for bigger, better clusters later this summer.

* Cut back fruit-bearing canes on berries.

* Warm weather brings rapid growth in the vegetable garden, with tomatoes and squash enjoying the heat. Deep-water, then feed with a balanced fertilizer. Bone meal can spur the bloom cycle and help set fruit.

* Generally, tomatoes need deep watering two to three times a week, but don't let them dry out completely. That can encourage blossom-end rot.

* Feed camellias, azaleas and other acid-loving plants. Mulch to conserve moisture and reduce heat stress.

* Cut back Shasta daisies after flowering to encourage a second bloom in the fall.

* Trim off dead flowers from rose bushes to keep them blooming through the summer. Roses also benefit from deep watering and feeding now. A top dressing of aged compost will keep them happy. It feeds as well as keeps roots moist.

* Pinch back chrysanthemums for bushier plants with many more flowers in September.

* From seed, plant corn, pumpkins, radishes, squash and sunflowers.

* Plant basil to go with your tomatoes. There’s still time to plant melons, pumpkins and squash from seed.

* Transplant summer annuals such as petunias, marigolds and zinnias. It’s also a good time to transplant perennial flowers including astilbe, bidens, columbine, coneflowers, coreopsis, dahlias, rudbeckia, salvia and verbena.

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