- A record 100 million-plus US households now garden, the National Gardening Association says.
- That means more Americans face the dilemma of how and when to water their plants.
- Watering frequency can depend on your location, the type of soil and plants, and weather.
Gardening has cultivated a growing crop of converts over the last few years – due in part to Americans staying home during the COVID-19 Pandemic.
A record 100 million-plus US households now grow plants, vegetables and fruits, according to the National Gardening Association. So there’s likely plenty of green thumbs wondering about when and how to best water their plants – especially as the heat of summer bears down across the nation.
Common advice has been that your plants only need to be watered once a week. But is that enough? That depends, as many factors come into play arriving at an answer, experts say.
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Is watering plants once a week enough?
And it is. Maybe. If you water correctly. And if the weather cooperates.
Ideally, you want to give your plants or garden about an inch or so of water across their soil each week. The goal is to moisten the soil eight inches or so below the surface; and even deeper for bigger plants, shrubs and trees. By soaking slowly, the water will permeate the soil.
“It is not necessary to water every day, it is better to apply the water deeply less frequently,” so the water reaches down into the where the roots are, said Heather Stoven, an associate professor and community and small farms horticulturalist at Oregon State University.
But how much you have to water will depend on several variables.
There’s the type of soil – clay soils hold more water than sandy soils, Stoven said, – and weather, as sometimes rain may supply plenty of water, especially for established plants.
What you are watering makes a difference, too. New plants, trees and shrubs need more moisture as they develop roots, so you will want to water them at least twice a week during their first month, said Cheryl Boyer, a professor in the department of horticulture and natural resources at Kansas State University in Manhattan, Kan.
If your plants are in raised beds, they may need watering more frequently also because the soil dries out more quickly, she said. Plants in containers also need more frequent watering, compared to those planted in the ground.
How often should you water annual plants? What about trees? Grass?
Annuals, plants that die in the winter and must be replaced the following spring, typically need more water than perennials, which return each year. But annuals still benefit from less frequent, but soaking watering, which encourages sturdy root growth.
Trees and shrubs need about 10 gallons of water each week, Boyer said. If you have sandy soil, split the watering into two five-gallon sessions, separated by three or four days. Trees larger than two inches in diameter need even more water; measure the tree’s diameter six inches above the ground and add 10 more gallons per inch, she said.
As for lawns, grass and turf should be watered multiple times a week, “since their roots are shallower and tend to dry out faster,” said Virginia Cooperative Extension horticulture agent Adria Bordas.
What is the best way to water your plants?
►Garden hoses. The easiest way to water is with a handheld sprinkler or spray wand connected to a hose. But those methods may result in under-watering of your plants. When you use a sprayer, “often the water will run off the site, or not enough will be applied for the water to move deeply into the soil, this is especially true with a strong stream of water,” Stoven said. “The water needs to be applied slowly and for a long enough time so that the water can soak into the soil to the root zone.”
►Sprinklers. These aren’t the best option, either, because they “often apply the water where it is not needed, such as onto a driveway,” she said. “Also sprinklers lose more water to evaporation from wind and heat.”
►Soaker hoses. The most efficient and least wasteful way to water is with a soaker hose or drip irrigation system, which has tiny holes in it to allow water to seep out. “The water goes directly onto the surface of the ground and more likely makes its way deeper into the soil,” Stoven said. “You can wrap it around your tree, too, to make sure the area around the trunk gets fully saturated.” If you wrap a soaker hose around your tree, make sure not to place the hose directly around the trunk. Arrange it close to the trunk for new trees and farther out toward the tree’s dripline, equal to the spread of the tree’s branches, for more established trees. “Applying a lot of water directly around the trunk can encourage disease,” she said.
►Other watering options. Another option for trees and shrubs is a tree watering bag, which may hold up to 20 gallons of water and will slowly deliver the moisture to the plant. As your tree ages, you can water less frequently – every 10 to 14 days in the second and third year and even less frequently after that, Boyer said. “Soaker hoses and tree bags release water right where it’s needed, over a longer amount of time so that the water soaks in slowly and deeply, encouraging deep root establishment,” Boyer said. That also helps the tree grow stronger and able to handle drought conditions, she said. Don’t want to buy a soaker hose or water bag? Cut a couple ⅛-inch holes in a bucket and sit it near your plants. For trees, change spots each watering session.
How do I know if my plants need water?
You can use some simple tools to help know when it’s time to water. An inexpensive moisture sensor probe can be inserted into the soil to assess how dry it is, Bordas said. The probe will also give you a “a good idea how deep you are watering,” she said. And a rain gauge can “help you track natural irrigation,” she said. “Placing rain gauges throughout your yard will give a better idea of how much water each site actually needs.”
But your senses can be your guide, too. You can use your fingers and feel how moist the earth is, Bordas said.
“The soil should partially dry out between watering to allow oxygen to re-enter,” she added.
If you don’t want to get your hands dirty, use a long screwdriver or other tool to stick into the ground near your plants and check to see how much moisture is in the soil on the tool when you remove it, Stoven said. If the soil is dry, you need to water. If it’s still moist, check back in a couple days.
If smaller plants are wilting – and you haven’t watered them recently – water them right away, Boyer said. (A note: if a plant gets too much water, it can prevent the roots from taking in oxygen. That can cause them to wilt, too.)
What’s the best time of day to water plants?
Most experts recommend watering in the morning. If you can’t water early, finish your watering about 30 minutes before sundown. “You want to apply water at a time when the leaves will have time to dry off, so they don’t host fungi and diseases,” Boyer said.
However, during the heat of the summer, most plants will dry quickly whenever they are watered, she said. So if it’s easier for you to water in the evening, that works, too.
If you use a sprinkler or hose to water from above, it’s best to water in the morning so that leaves can dry during the day. Otherwise, fungus can grow on them.
Watering during the summer
Plants use more water in the summer to maintain their growth, so water in advance of and during major hot or dry spells, Stoven said.
Even when it’s hot, make sure to check the moisture level of the soil, Boyer said. “Too much water, even if it’s hot out, can still end up damaging a plant if it doesn’t have enough oxygen. It’s a balance.”
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Set yourself up for gardening success
Choose plants that will flourish in your area. Native plants won’t need as much water. For instance, if you know you constantly have dry, hot weather, consider drought-tolerant plants, Stoven said.
Need help picking appropriate plants? Contact your local extension service or nursery. You can also find native plants on the National Wildlife Federation’s website.
Using mulch and adding compost to your soil can also help keep moisture in, Stoven said. “Plants should also be grouped together by water needs, so that plants that need consistent moisture aren’t right next to plants that don’t need much,” she said.
Pay special attention to your new plants. “Plants are resilient and most are pretty tough. Basic care is often adequate, especially after they’re established,” Boyer said. “It’s those early days of care after planting and any attention at all when the heat is on (or the drought of winter) to keep them going and help them grow well.”
Follow Mike Snider on Twitter: @mikesnider.
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George is Digismak’s reported cum editor with 13 years of experience in Journalism