Watering strategies for hot weather

When hot temperatures without rain persist for three weeks or more, many of us need to take another look at our gardening habits. During the first week or two, gardeners who planned ahead for a dry hot summer can feel secure that they did most everything to prepare for times like this.
They added moisture-retaining compost or manure into the soil, they mulched with grass clippings (until the lawn stopped growing from the heat) and invested in soaker hoses - all valuable steps and relatively inexpensive. They bought far-reaching water wands.
But by the third week of drought, it's tempting to start dreaming about gardens where people had the forethought to install underground watering lines. Or they set up a system where winter rain gets diverted from the roof into a large, elevated storage tank.
Installing a rain collection system, which diverts water from one or more downspouts into various storage containers, is less expensive and more do-able. This can be a barrel, a tank or even a monstrous and tough plastic bag. There's lots of information on all of these online.
The old-fashioned way, which conserved small quantities of water, was to run the downspout directly into a large wooden or metal water butt. In my long-ago home, ours was never covered, and when I grew tall enough to peek in the top, it was fun to watch the mosquito larvae in summer.
Uncovered water never stays clean - but for mosquitoes, we now have Aquabac, which kills mosquito larvae in two hours. It is said to be safe for fish, people, pets, birds and plants.
The traditional, curved wooden water butts are so pretty, but if you take a lot of water out of them, the wood begins to shrink and becomes difficult to refill. You can have the same problem with half-barrel container ponds if they're not topped up frequently.
When the need for water is desperate, there's no problem using grey water from baths, showers, laundry or water where vegetables and fruit have been washed. If you're willing to let grey water accumulate, you can pump it to irrigate flowers and the roots of vegetables. But grey water mustn't be used for any part of a vegetable that you'll eat: soap and detergent sticks.
With watering, morning is the best time, then the plant can use water for growth during the day and withstand mid-day heat better. Watering in hot sun isn't good because leaves with water droplets on them can scorch.
Soaker hoses are especially useful under mulch, but water pressure should be checked. If it's too low, the water won't reach the end of the line.
Containers set against sunny walls are in double jeopardy – triple if they're also standing on concrete. Walls and hard surfaces reflect heat. In long hot summers, containers need very frequent watering.
If a container dries right out and it's too big (or heavy) to stand in water, try making many holes in the soil. Water will soak down into the holes instead of scooting down the fissure between the dry soil and the pot's side. A similar technique gets water down into the roots of drying-out shrubs and trees.

Anne Marrison is happy to answer garden questions. Send them to her via amarrison@shaw.ca  It helps if you add the name of your city or region.

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