In the Garden:
Northern California Coastal & Inland Valleys
High noon is not the time to water in the heat. The best time to water is in early morning. You'll conserve water and foliage will be dry before nightfall, which reduces disease problems.
Coping with Hot Weather
The dog days of summer can bring hot, hot days that can cook an unprepared garden. With that in mind, let's talk about a plan to help your plants get through hot weather without damage.
First and foremost, if you hear a weather report of predicted heat, water everything deeply. Try to drive the water down into the soil to meet the natural moisture level. Mulch provides excellent protection against moisture loss, so if you have the time, spread a few inches of fresh compost, bark, or whatever you have on hand. It creates a barrier that prevents moisture from evaporating. Mulch also protects the surface of the soil from baking in the heat. It's great around shrubs, trees, perennials, vegetables, and annual plantings.
You may see some wilting during the heat, especially in annual plants. Always feel the soil before you water. When it's especially hot, plants lose moisture through their foliage faster than the roots can take up water. If you apply water when they are in this state, you take a chance of damaging the root system. It's best to provide some kind of temporary shade if the soil is moist and the plants are wilting. Newspaper tents, old bed sheets, or row covers can be laid over wilted plants to protect them from the sun. Just make sure there is adequate air circulation under the covering. Stakes or recycled tomato cages work well as temporary supports for coverings.
There are products available that prevent plants from losing moisture from transpiration. Wilt Proof and Cloud Cover are two products that temporarily seal the surface of the leaves to prevent moisture loss. Interestingly enough, in freezing temperatures plants benefit from an application of an antitranspirant for the same reason.
Fruit can become sunburned in very hot weather. Fruits on apple, peach, and plum trees can develop sunken yellow, brown or bleached areas where high temperatures caused tissue damage. Cover plants with shade netting during hot spells can help prevent problems. If possible, remove sun-damaged fruit from the tree as soon as you spot it. Otherwise the fruits are likely to rot on the trees.
Usually tomatoes relish the heat, but occasionally you will get some sunscald on fruits not protected by the foliage. Keep plants healthy to maintain good foliage coverage, and shade vines with a lot of exposed fruits during heat waves.
Sometimes, tender ground covers, such as hypericum, develop brown edges along the leaves from heat. Once September rolls around and the days start getting shorter, you can trim back the burned foliage and still have time for a flush of new growth before the cooler weather sets in. Fertilize with a low-nitrogen fertilizer, and water after the haircut.
When it's really hot, water only in the early morning hours or after the sun goes down. Your garden will thank you. And by all means, wear a hat and sunscreen, and don't do heavy gardening chores during the heat of the day. Keep an eye toward the western horizon for the arrival of that lovely fog bank.
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