Rosie: Hi. I’m Rosie Lerner. I’m the Extension Consumer Horticulture Extension Specialist here at Purdue, and I want to talk to you a little bit about what to do in your yard and garden during times of drought or extreme dry, hot conditions like much of the state has been experiencing this year.
In addition to having a really early season, our summer started way early and so did our drought. Now we have a lot of plants that are really under stress. You might be seeing a lot of wilting, some leaf scorch, perhaps even die-back on many of your plants.
Now it’s time to do a little bit of assessment in your garden. You may need to do what we like to refer to as “triage” in the garden, where you kind of decide which plants are most in need of some rescue irrigation. You may have too many plants, maybe your area is under watering restrictions, you many not be able to get to water everything to keep it all in its very fit, fine shape. Now it’s time to take a closer look at which things are most under stress or perhaps at most risk of having problems in subsequent years if we don’t so some rescue watering right now.
When we’re talking about ornamental trees, shrubs and flowers, the newly planted items are going to be the most at risk for succumbing to drought. Generally speaking, about an inch to an inch and a half of water every week in a nice gentle, thorough soaking is the optimum. You’re probably not going to be able to do the optimum, so it would be better to water slowly and deeply and less frequently. If you had to go every two weeks or every three weeks and let them sort of survive in between, that would be better than watering shallow and frequently every day, because that would tend to encourage a more shallow root system that is less likely to be able to withstand drought for the long haul.
In the fruit and vegetable garden, watering is just as important, if not more important, than in the ornamental garden. Particularly for plants that you’re trying to harvest, that they’re already in production and especially those plants that produce a fruit for their crop, things like peppers and tomatoes and squash, cucumbers and your fruit trees and your small fruits.
When plants are trying to pollinate and set fruit, that is a really critical time that they not be under drought stress if at all possible. Irrigation is really key for those crops.
Also mulching will be a big help in conserving what moisture you do have in the soil, whether you’re watering or not watering. It will tend to keep the soil a little bit cooler if you’re using an organic mulch. It will also tend to help suppress weed growth. It won’t stop all of them, but hopefully it will keep down much of the weed growth and, of course, the weeds will compete with your plants for that water. Mulch will help conserve the moisture you do have and slow down the weed growth.
The best time to water your garden is either early in the morning or late at night. The problem with late at night is that it will keep the foliage wet for a prolonged period, which kind of encourages the possibility for disease infection, so we’re back to first thing in the morning being best. In fact, if you could finish you watering by about 8:00 in the morning, that would be the optimum time from an efficiency standpoint. That’s when the temperatures are cooler but the plants are going to dry off quickly. Usually the wind is quite still. What you don’t want to do, if at all possible, is water in mid-day sun where it’s very hot. Usually that’s the breezier part of the day. You’re going to lose a lot of that water to evaporation and wind blowing it away, so it’s not the most efficient use of your water.
Many gardeners will wonder if they can use what’s called “gray water,” which is household washing water, like from washing dishes, maybe from doing the laundry, maybe even from showering. That kind of soapy-residue water might be okay as sort of that rescue, need-to-help-my-ornamentals-through kind of watering, but you don’t want to make a long-term habit out of it because that soapy residue has some salt build-up and perhaps other contaminants that might not be good for the long term for the health of your soil or for the plants. You never want to use the gray water on your edible crops, on fruits or vegetables or herbs. Stay away from that.
Also softened water, that has used salts to soften the water, that also has a high amount of salt residue, of course. It’s best to bypass the water softener when you’re irrigating your plants.
For our perennial plants and especially our woody plants, everything that happens next year is going to be impacted by what happens the summer before. That’s when the plants are putting on their buds for foliage as well as for flowers that eventually become fruit. A drought in summer can definitely have a big impact, a negative impact, on next year’s flowering and fruiting.
For more information on managing drought in your garden and landscape, check the Purdue Extension site at purdue.edu/drought.