Here are my recommendations:
1) Lawns: Don’t worry about the lawn. Our lawn grasses will tolerate drought by going dormant (turning brown). When it rains, they will green up again. If you feel compelled to water the lawn, then provide an inch of water a week, preferably at one watering over a period of a couple of hours. This is to provide a thorough watering without a lot of run off. Frequent light watering result in shallow rooting. Infrequent deep watering is better.
2) Hanging Baskets: Hanging baskets in the sun are not the happiest of campers right now. You may find that it’s difficult to water frequently enough to keep them looking good. Move them to an area with afternoon shade, or consider perhaps taking them down and planting the plants into a larger on-the-ground container, or even into the ground.
3) Containers: Check daily, water as needed. If the soil feels moist, let it go a day. I have some ceramic containers in the shade that only need water once a week, even in this heat. Terra cotta containers in full sun may need daily watering. If a pot (or basket) gets very dry, the soil may shrink away from the side of the pot. When you water, the water runs down the side of the soil ball instead of penetrating the dry soil. That will call for repeated watering over a period of a couple of hours to get the soil wet enough to swell back to contact with the container. If it’s small enough, you can set it in a tub of water for an hour to rehydrate.
4) Newly Planted Perennials, Trees and Shrubs: check them daily. How frequently they need water depends on what you have planted, and where it has been planted. Plants in the shade may only need water every four or five days. Newly planted shrubs in the sun may need water every day or two for awhile. Remember that initially, all of the roots are in the soil ball that came with the plant. Even if the surrounding soil is moist, if the soil ball dries out, the plant wilts. As in the description above for containers, if the soil ball is dry, water may not penetrate it easily.
The absolutely best way to water is to use a water wand (a hollow pipe attached to the hose with a “breaker” on the end. A breaker is like the end of a watering can that breaks the water stream into many small gentle streams.) All professional garden center and nursery people use water wands. (Except for management, which thinks it has earned the right to spray plants with a thumb over the end of the hose once in awhile.)
The reason to use a wand is that it lets you get the water exactly where you need it—into the hanging basket, or at the base of the plant at the soil ball. While spritzing the foliage with water may make you feel good, it doesn’t do much for the plant. It absorbs water from the roots, not the leaves, so apply a gently, soaking stream of water to the soil ball area. Twenty seconds ought to do it for smaller plants.
5) Established plants: It’s a tricky call. Shallow rooted plants like azaleas must have regular watering in hot weather. A good soaking once a week should be enough. Personally, I have invested (tens of) thousands of dollars in my garden over the years, so I am going to water during dry spells.
In this weather, if it hasn’t rained heavily for a week, I start up the sprinkler and water one piece of the garden very early each morning while it is still cool, over the course of a week, for about an hour to an hour and a half in each spot. Other horties will water by hand with a wand, selectively: say, all of the hostas, letting established trees fend for themselves.
Another tool in the aquatic arsenal is the soaker hose, which sort of oozes water out along the length of the hose; the advantage is not losing water to evaporation, a big problem with fine mist coming from a sprinkler in hot, dry air. These can be wound through established plantings, or are good for along the rows of vegetable gardens. I have used them and they work. I personally find it hard to monitor how much water I am using, and you may water a shrub while the hosta a foot away upslope is bone dry. So, let’s say they work well in specialized situations.
6) Gray Water, Rain Barrels, Eco-Stuff: Fine. If you have a small area to water that is easily watered by hand then save the water from the clothes washer, shower with a bucket, gather rain water in a rain barrel, and use it.
Every gallon helps; it’s a function of how big an area you need to water and how much time you have to do it. The rain barrel also helps reduce runoff during storms, so it has that additional benefit.
7) Behnke’s Sells Everything You Need for Watering: From the rain barrels, to watering cans and hoses, and water wands in numerous decorator colors. This is the season, now is the time.
By Larry Hurley, Perennial Plants Buyer