by Brian Minter
After five months of cooler, wetter weather than I’ve ever seen before, we're about to experience some record hot temperatures over this long weekend. It looks as though the weather will be great for swimming in pools and lakes and for barbecues, and as nice as this may be, dry hot weather can be tough on our plants.
Sudden heat and soaring temperatures create a demand for moisture that cannot always be met on short notice by the root systems of many plants. The result is burnt blossoms, damaged foliage and hard, stunted growth. Fortunately, there are ways of minimizing the problems caused by a sudden hot spell.
The most immediate relief for plants is a thorough, deep watering. It is best to do this early in the morning when the plants will make the greatest use of the water. Watering in the evening wastes water because plants simply transpire valuable moisture away. The other huge issue is where to water. Soaker hoses around the perimeter of all trees and shrubs is the most effective way to water. A little water is worse than no water. When you water, saturate the soil deeply where the roots are to keep them going downward instead of upward in an effort to capture what little moisture there is.
The next most important task is to mulch many of your trees and shrubs with suitable material. You should be looking for something that is a good insulator, can eventually be worked into the soil and has an attractive appearance. Garden compost is fine if it is well broken down, but its appearance is not always the best, especially when it dries out. Manures are also fine, but remember that they are slightly on the alkaline side and can cause problems with your acid-loving plants like rhododendrons and camellias. If you use manures, be sure they have been composted for at least six months. Grass clippings are quite suitable in the short run but once dried out, they tend to look rather shabby. My preferred choice is always fir or hemlock bark mulch. Bark is a wonderful insulator, it looks great and makes a fine soil amendment. A covering of three to four inches around all your plant material will prevent a great deal of stress, especially for shallow-rooted plants like rhododendrons.
Hedging cedars are very shallow rooted and will dry out quickly in a few days of intense heat, so use soaker hoses to alleviate this problem.
A thorough watering is the most important stress-relieving factor for all the plants under the eaves of your home. Heat reflected off buildings can be a real challenge for plants, so please do not neglect both the sun and shade areas under the eaves. Here, too, I find soaker hoses and drip systems are, by far, the most efficient and thorough method of watering.
Remember too for all your veggies, annuals, perennial beds and containers, try to get in the habit of watering very thoroughly to make sure the roots and soil mass are moist down deep, not just on the surface. Water less frequently, but really soak the soil when you do water. Keep water off the leaves of tomatoes and potatoes for fear of blight and especially off cucumbers and squash to help prevent mildew.
Lawn grasses are very resourceful. It is far better to water less frequently but when you do, water deeply to get the roots going deeper into the soil to find more moisture. If lawn grasses don’t get enough moisture, they will simply go dormant, coming back in autumn when the rains return. Recently laid turf and newly seeded lawns are another issue. They require moisture until their roots are well enough established to withstand drought.
For all plants, proper soil preparation is really the key. When you plant, make sure the planting hole is at least twice as wide and deep as the root ball and contains lots of organic matter to create an environment where plants can be self sustaining over the long haul. Plants need soil that both drains well and yet has the ability to retain moisture during long dry periods.
Try to move away from overhead sprinklers and towards root soaking systems. They are much more efficient and are great water conservers. It only makes sense to water where the plants are versus soaking everything!
Don’t be fooled by wilted leaves and assume a plant is dry. Often heat stress causes wilt and the plant will bounce back in the cooler evening temperatures. Overwatering can cause root rot, something that happens all too frequently.
With proper soil preparation, mulching and watering, all our garden plants should be able to withstand both heat and water restrictions. To conserve water, we all need to change the way we use water around our homes, even collecting it from our eave troughs when it does rain.