Drive around your neighborhood on a hot summer day, and you'll see many approaches to watering plants. Some homeowners break out the hose at the end of the workday, while others program the automatic sprinklers to come on at dawn for 15 minutes a day; still, others figure on the plants getting a drink whenever the kids decide it's time to play in the sprinkler. However, timing your irrigation will not only lead to healthier plants, but it can also save on your water bill.
How to Water Plants in Summer
Watering plants in the summer can be an art. Too little or too much water isn't good for gardens. Seasoned gardeners follow this rule of thumb: Water deeply and less often rather than watering too little too often.
Evenly water your plants using tools like soaker hoses for beds and watering cans for containers to give them consistent moisture. Letting the soil slightly dry out before watering can promote growth. You also don't have to fertilize plants in the summer; they are already stressed by the summer heat and need to use their energy to absorb water, not any extra nutrients.
Keep an eye on soaker hoses to make sure they are in good working order. Degraded hoses can create little fountains of water that can flood parts of a garden while leaving other portions dry.
When to Water Plants During the Day
It's a good idea to administer water from an overhead device like a sprinkler or rain wand early in the morning. That's because watering at this time of day allows foliage to dry quickly, which discourages fungal spores. But if you don't have time in the morning, it's perfectly acceptable to do evening watering. In the evening, just be mindful of watering more directly to the root zone rather than the leaves. A watering in the cooler evening soil can have its benefits, too, because the moisture won't evaporate so fast, giving it time to soak into the dirt.
Watering Annual and Perennial Plants
Whether your plants are annuals or perennials, try watering them in the morning during a heatwave. Morning watering gives the roots a good soaking and offers your plants enough moisture to get them through the day. But during summer scorchers, you may need to water annuals and perennials more often.
Annuals are plants that finish their entire lifecycle in one growing season. This includes garden favorites like marigolds, impatiens, and pelargoniums. These plants have very shallow root systems and will suffer when the top few inches of soil dry out in the summer. You must water them frequently, even daily, when the mercury rises.
Perennial plants have deeper root systems that enable them to survive periods of drought from one season to the next. Some perennials, like butterfly weed and false indigo, have taproots that extend many inches into the soil, in effect tapping into water reserves during periods without rainfall. The best time to water perennial plants is once or twice a week, slowly and deeply so that the water does not run off before it has time to soak into the soil.
A rain gauge can be helpful; many plants thrive on about an inch of water per week.
Containers can dry out quicker than garden beds, so it's best to increase watering in the summer. During heatwaves, water container plants twice a day, once in the morning to give plants a boost before the sun begins to bake down, and once in the evening to replenish what the day took away. However, the type of container can also affect watering frequency. For example, plastic and fiberglass pots are nonporous which means they'll hold moisture well, so you need to be aware of overwatering. On the other hand, terracotta clay pots are porous, breathable, and can insulate roots from heat, but soil can dry out quickly requiring more watering.
Try self-watering containers. Tropical plants and some vegetables, like tomatoes, do well in these types of pots which have water reservoirs inside of them to give plants consistent moisture.
Dry vegetable gardens can lead to blossom drop, stunted vegetables, or even plant death. Vegetable gardens need deep watering at least two to three times a week and best in the mornings to keep the soil moist. Vegetable plants that may need extra water during heatwaves include cauliflower, celery, cucumbers, peppers, radishes, and squash. These plants demand consistently moist soil to produce the best crop. Use drip irrigation, or place a soaker hose at the base of your plants to avoid wetting leaves. If you must rely on sprinklers, water early in the morning to allow the sun to dry the foliage.
Trees and Shrubs
Passing rain showers can't give your trees and shrubs the adequate amount of water they need in the summer. Trees and shrubs need deep watering to encourage a healthy root system. Sometimes the best time to water them is right after a light rain to help the moisture sink into the soil. The time of day you water plantings isn't nearly as important as giving them a thorough soaking.
Try to follow this loose guideline for trees and shrubs:
- Mature trees and shrubs: For a deep watering, place a hose at the base of a shrub or tree, and let the water run until the top 8 inches of the soil is moist. Do this every few days for established trees and shrubs.
- Shallow-rooted specimens: Hydrangeas, dogwoods, Japanese maples, and magnolias will need extra water—at least three times a week—to prevent dehydration.
- New plantings and transplants: Newly planted or transplanted specimens have small, still developing root systems that need encouragement to settle in. It can take at least two to three years before they are considered established. To encourage them, water deeply twice a week. Let the water soak into the soil which will stimulate the new roots to grow deeper into the soil.
Keep watering through the fall to prepare plants for healthy winter dormancy.
How to Help Wilted Plants
When plants are wilted from lack of water, watering them should perk them back up quickly. However, other things can cause wilting, including pest and disease problems, and even overwatering (if the soil is moist and the plant is drooping, this could be the case). Furthermore, plants can wilt on a hot day as a way to conserve their energy to cope with the high temperature, but then rebound when the evening cools off. In time, you will get to know your plants and will recognize those that respond to heatwaves in this fashion.
Summer Watering Tips
- Plants absorb water through roots, not leaves, so you don't need to waste water on leaves that appear to be dry.
- To tell how deep the water is penetrating the soil, use a stiff metal rod. Push it into the soil after you water and it will stop when it hits dry dirt.
- Use a thin layer of mulch to help your plants conserve water during hot summers.
- Irrigate your garden with pure rainwater by setting up rain barrels near gutters and downspouts or install a rain garden to collect runoff. Plants will thrive and it can reduce your water bill.
- Another way to conserve water is to bury unglazed clay pots in the ground and fill them with water. This ancient way of irrigation uses low-fired vessels, called ollas, to let water consistently seep through the clay walls to nearby plants and trees.