Diagnose and Prevent Drought Stress in Plants

A droopy, wilting plant. It’s a gardener’s instinct to automatically assume: It needs water. And sometimes, that’s a good instinct. But low-water plants just as easily can be killed by kindness as by neglect.

gladiola
Gladiolas like an inch of water a week, but not too much water.

For example, several problems with tomato fruits are caused by too much water, or especially irregular watering. Plants, like people, need some regular hydration. You wouldn’t avoid drinking water for five days and then gulp down a liter, right? One reason drip systems are effective is the consistency (assuming you set a timer) of the amount of water they deliver, along with the slow rate of flow and the fact that they water the soil/roots and not a plant’s leaves. The delivery and slow flow help retain more moisture and nutrients around the roots.

A drip system with adjustable emitters is a great way to water our okra. And it looks like to attract ants...
A drip system with adjustable emitters is a great way to water our okra.

What’s the prognosis?

There are reasons other than drought stress that cause plants to wilt, including problems with the roots. That’s why plants you’ve just transplanted from seed or a nursery container tend to wilt for a few days or weeks. The roots suffer some damage when taken from a pot and replanted. Understand that this is part of the natural course of the plant’s life and help it through without stressing too much (meaning you, not the plant). Even though a plant is waterwise, it still needs extra water until the roots heal and begin to grow, more efficiently pulling water into the plant. If the ground is dry at root level, the roots can’t do their work. Plants that are overwatered sometimes wilt, too, further complicating the “diagnosis.”

tomato branch broke water
After our first heavy rain, I accidentally brushed against a branch of this currant tomato.It peeled off; the brown leaves are likely from that damage, not from lack of water!

Speaking of, most gardeners jump to the worst possible scenario when determining a plant problem. Although disease is a possibility, look not only for symptoms of a particular wilt or fungal disease, but also for possible causes. Do you have evidence of bugs that might have damaged leaves or carried a disease to your plant? Is the plant getting enough air circulation? Is water running off and away from the plant? Has it just been super hot for several days?

incipient wilt
Incipient wilt on a squash. Still not the best scenario and a signal to check our soil, but it’s temporary.

The best way to distinguish drought stress from other causes of wilt is by looking at and feeling the soil. Damp soil means the plant has water available; adding water at this point likely won’t help. You should feel an inch or two below the surface. One way is to stick your finger in the dirt to about the first knuckle joint.

Prevent plant stress

When a plant needs water, it’s more susceptible to damage from bugs and diseases. Pests attack the weak. You can prevent plant stress from underwatering by:

  • Checking the soil as mentioned above; see if there is water for the plant.
  • Looking for signs of underwatering. These usually include leaves turning yellow and brown, and even falling off. Typically, drought stress begins with lower leaves.
  • Thinking about the plant’s environment and how it might have changed. Is it windy and hot or muggy and cool in the evenings? Did you last water a plant in the afternoon out of necessity instead of your usual morning routine?
hot day on plant
Not much you can do about these weather conditions within a week or so of placing new plants in your landscape. Water consistently in the morning and shade plants if practical.
  • Using a meter or records when in doubt. We have an inexpensive moisture meter for our farm area. If nothing else, it helps confirm or deny my suspicions about the need to water and gives me a basis for comparing soils or drip rates around certain plants. Keeping records of watering, fertilizing and other activities can help manage and diagnose plant problems.
water meter to check moisture
Geraniums like to dry a little between watering. An inexpensive meter might not be the most accurate tool, but can help a home gardener check soil moisture.
  • It’s always better to water before a plant wilts, and not to wait until wilting occurs. Although plant roots need to seek water, they also have to find it! When no water is available in the soil around them, plants can begin reacting with wilt, slowed growth or flower and fruit production, and other signs.
xeric bush spirea
Blue mist spirea is a low-water plant. If the leaves have spots, it’s more likely getting too much water than not enough.
  • Finally, remember there is no hard and fast rule on watering. Much of the advice I see comes from areas that are more humid, cooler, less windy, and at lower altitude than our conditions here in New Mexico. Having said that, you can create conditions that help plants retain moisture, mostly by ensuring healthy soil and mulching. Containers need a little more frequent watering because they dry out faster than the ground. Water container and landscape plants slowly so the moisture drips instead of flooding down. You probably only need to add water to a container when the top few inches of soil are dry.

 

 

Safely Use Rain Water on Vegetables and Herbs

It seems that Los Angeles officials are considering installing cisterns with smart technology to catch rain water for irrigation. It’s about time. Even when rain barrels and cisterns fail to collect all of the water that falls from the skies or flows from the roof, they still make use of water that might otherwise run off and go to waste. And homeowners can use the water for ornamentals and even edibles.

rain barrel metal roof
This is one of two rain barrels by our house. We used it to water the carrots in the pot next to it one year, along with container tomatoes. It also serves as a handy drinking spot for the mutts and apparently as a shelf for my wind chimes when they annoy my husband as a storm such as this one comes in.

I don’t know much about LA and its politics, but I do know that when I made a trip to southern California recently, water restrictions were forcing patches of brown grass more than landscape alterations. Pulling up some of the grass, replacing it with a few vegetables and herbs, and then watering those edibles with rain water seems like a really smart and sustainable solution.

We’ve been using rain barrels for many years. When we had a flat tar and gravel roof and city water in Albuquerque, N.M., we limited use of the rain barrel to ornamentals only. But now that we rely on a well, grow more food on more land and have metal roofing, we use rain water on our vegetables and herbs.

rain barrel for watering ornamentals and edibles
Here’s the same barrel up close and right after we put it into service in early spring. I know I can’t water everything with it, but we don’t need to. Most of our ornamentals are xeric and need no regular watering. Why not capture some rain to use where we can?

Before collecting rain water for edibles, I researched the topic and found little information, but enough to make me feel comfortable using the water. Since then, more data is out there confirming that for the most part, collected rain water from common roofing materials is safe for edibles as long as you follow a few preventive collection and watering practices. Most of my tips are about barrels, which is all I have so far. I would love to have a cistern; it’s on my wish list! To learn more about the data and specific roof material information, check out the Resources page under Rainwater Collection and Rain Barrels.

Safe Rain Water Collection

None of the research claims that collected rain water is potable. There are just too many variables. In urban areas, pollution settles on rooftops. Where I live, critters and birds fly over or hang out on the gutters, likely leaving droppings. Here are a few ways to make your collected water safer for vegetable use:

  • Clean rain barrels with a bleach solution before using them for edibles. Rutgers also recommends adding eight drops of bleach per month for a 55-gallon barrel, and waiting 24 hours before using the water so the bleach can dissipate.
  • Rinse out barrels once a year, removing sediment and using either bleach or a vinegar and lemon solution to clean the barrel.
  • Keep gutters clean and free of debris, which also makes good sense for roof maintenance.
We installed a new rain barrel system on the shed near our vegetable garden this spring. We can see the roof well enough to know whether there is anything we need to clean off!
We installed a new rain barrel system on the shed near our vegetable garden this spring. We can see the roof well enough to know whether there is anything we need to clean off!
  • When installing a new system, it’s recommended to have a first-flush diverted added. This washes the first flush of downspout water, along with debris and contaminants, away from the barrel before it begins filling.
  • Most commercial barrels have screens to keep debris (and birds or other small animals) from getting inside the barrel. Be sure to wipe the screens off from time to time. Even leaves can rot and drip into the rain water.

Safe Watering 

Of course, you can choose to water only ornamental and house plants with rain water if you have any doubts. I also tend to alternate watering between my barrel and well for vegetable rows, just to mix up the nutrients and potential metals from both, and because the barrel by the garden usually empties before the next good rain. For safest edible watering, be sure to follow these tips:

  • After a barrel fills, use the first full bucket or so on ornamentals, not on vegetables or herbs. This first flush from the barrel usually contains more contaminants because of settled water at the bottom.
  • Always water the soil and not the plant, a best practice for gardening anyway. And the soil absorbs the water, not the leaves. This is especially important for any edible you harvest from above the ground (or other than root vegetables).
Drip irrigation is the best method for watering efficiently and safely, and can work with some rain collection systems.
Drip irrigation is the best method for watering efficiently and safely, and can work with some rain collection systems.
  • Water in the morning and wait to harvest, after the sun’s rays have dried and disinfected the plants.

Finally, those folks in California can water their lawns (hopefully less by switching to native, low-water grasses) with cisterns, which typically have pressure valves. Most smaller rain barrels lack the pressure required to drive soaker hoses. Raising your barrel a few feet can increase the pressure to allow use of a hose or drip system, but likely not enough to run a lawn sprinkler. In the past, we’ve used stacked square pavers or cement blocks to raise ours.

This is the view of the new barrel from the vegetable garden, just before a storm. The barrel is slightly uphill, so we get good flow, but I might raise it more next year.
This is the view of the new barrel and shed from the vegetable garden, just before a storm. The barrel is slightly uphill, so we get good flow, but I might raise it more next year.

Low-water Use Tips To Meet Restrictions and Good Water Sense

We spend a lot of time talking about xeric plants, and recently posted some tips on low-water use for gardeners. California has implemented emergency regulations to conserve water during their drought, and the ones related to landscaping are the sort of common sense practices that xeric-minded organizations and gardeners have always touted:

  • Avoid runoff when irrigating.
  • Don’t irrigate during or 48 hours after measurable precipitation.

This post goes into more details on the restrictions, which, along with scheduled days or times of watering, are pretty common municipal regulations in drought-stricken areas.

Avoid runoff when irrigating

Runoff obviously can come from too much water. Of course, good planning of landscape, plant selection and irrigation choices upfront can prevent runoff. Correct an existing problem by first checking the area after the system runs. If you normally water while at work, do a manual run so you can test your system on the weekend. If you have runoff, study where flow occurs. If it’s down a slope, consider terracing the lawn area or welling around the tree or shrubs that you’re watering. You can also cut watering time, of course. If you’re worried about one tree or ornamental that needs more water, cut the irrigation system watering time and supplement the tree’s water every once in a while with a hose or bucket. Don’t waste all of that water irrigating concrete or pavement, and possibly weeds, just to keep one plant healthy. For a small lawn or several plants on a drip system, you can decrease watering time and increase frequency if necessary.

terraced lawn to prevent sprinkler runoff
This Albuquerque lawn has some bermuda grass, but notice the terrace to avoid runoff. Also, note the exposed drip lines being reset in the xeric garden area on lower right.

The runoff might be from a misdirected, leaky, plugged or defective head or emitter. It’s easy to turn and redirect the head so the water goes where it should. A small leak in the system can waste hundreds of gallons of water. Plugged sprinkler heads are a common cause of pooled or misdirected water. Running a stiff wire, such as a straightened paper clip, through the emitter hole can clear some debris. If the entire head is full or dirt or grass, you can turn off your system, lift and unscrew the head, soak it and use a small wire brush to clean it. Then rinse it and screw it back on.

Avoid watering a wet lawn

This should be a no-brainer, but I already ranted in my previous post about neighbors who left their automatic sprinklers on no matter the weather. My best advice is to set automatic sprinklers to “manual” and water regularly but only as needed based on weather conditions. You can set a reminder on your smartphone or other device to jog your memory if that’s a concern. But it’s sometimes more difficult to remember to override the automatic setting on the sprinkler, especially if you’re not there to do it! Otherwise, pay attention to the weather forecast each evening and override the auto setting when rain is predicted the night before so you don’t have to add the task to your busy morning schedule. You can always water a little in early evening or the next morning if the forecast is off the mark.

Of course, if you’ve switched out some or all of your turf for a xeric landscape, at least you are using less water. It also means less need for an automatic system. Most xeric plants need such infrequent watering that you’re best served by a manual irrigation system or the totally manual system of carrying a water bucket from your rain barrel only to the plants that need a little more water — and only when they need it!

raised ornamental bed bubblers
We raised part of this bed and replaced spray heads with bubblers to conserve water.

Other water-saving tips

  • Water early in the morning, especially if you live in a hot climate. Your plants take up more water before the stressful heat of the day, and if you’re using spray irrigation, less water evaporates.
  • Use drip irrigation when possible instead of sprays and sprinklers, or at least keep the spray as low as possible. Spraying water can lead to some leaf diseases, and you want most of the water to go into the plant’s roots, not into the air.
  • Well around plants, especially new plants, any plant that needs more water than others, and anything planted on a slope to trap the water.
  • Choose xeric, low-water and native plants.
  • Use mulch as appropriate to help keep plants cool and roots damp.

    welled shrubs
    Wells around shrubs at Tucson area nonprofit

Of course, it never hurts to call in a professional landscaper or other pro to get some help with your irrigation system or to better plan your lawn and garden for low-water use. For example, avoiding steep slopes in your landscape (with terraces and other strategies) can prevent water runoff, and use of microclimates can increase plant viability while decreasing water needs.

Fall List of Water-saving Activities

The weather is cool and plants are going dormant, but there still is plenty homeowners can do to improve water saving and plant health for spring. It will keep you in the water-wise frame of mind and cut down on spring chores.

First, if you have automatic sprinklers or drip systems, be sure to adjust them for your plant’s new winter watering needs. I used to lose it when I would see my neighbors’ lawn sprinklers running full force on a windy and frosty November morning, partly because I nearly froze getting into my car, but mostly because of the wasted water. Watering plants too heavily in fall weather can soften them and make them more vulnerable to frost damage. And if you continue to water them too much in late winter or too soon in early spring so that they leaf out, they’re more vulnerable to late frost damage.

Another good fall project is to mulch around plants. Some xeric plants do better without mulching, but those that need a little more water can benefit from mulches that help retain the moisture. Mulching now also protects more sensitive plants from potential frost.

mulch in bed
Mulch in this bed helps hold in moisture. Note the manual sprinkler control near the home’s front door. It’s not much more work and avoids watering when unnecessary.

Well or shore up plants. Leaving a shallow depression, or tiny well, around low-water plants helps hold moisture in, especially right after they’re planted. If you have some trees and ornamentals that already are established, you can shore up some of the water by building up a ridge of soil around the plant’s base. This is particularly helpful for plants on grades to help prevent water from running off the plant instead of soaking in.

apple_tree_well_web
Tim built up a ridge around this small apple tree to help well the water.

If you’re really feeling industrious, start planning for spring by planning or setting up a water harvesting system. It might be as simple as diverting roof water into a flower bed against the home’s foundation or so that it runs through a dry-river bed (an assortment of rocks and gravel made to look like a river) that leads to a favorite tree. Or plan a new xeric layout for your yard.

calif_poppies
This post lacked color, so I had to add these. Called California or Mexican poppies, they’ll grow in the poorest, driest conditions.

Raindrops Kept Fallin’…

There’s always some irony in gardening. I’m writing about drought-tolerant plants several hundred yards from an area struck by fire no more than five years ago and under severe water use and fire restrictions all spring. We prefer many xeric plants and inherited a huge and well-planned xeric garden when we moved here in April. Most of the plants survived with no care or water, outside a little rain from Mother Nature, while the property sat on the market for a year. So we were ready to look for more drought-tolerant choices for a slightly cooler zone and purchase rain barrels in case the skies ever opened up.

early rain
Early summer rain. See how brown the grass is? What grass, you say?

People who live in rural areas know their weather. One reason is that they tend to pay attention to the skies, the land, the views. Another is that many grow lawns, crops, or feed for livestock. And one of the best reasons is that no television station, web site or app gets rural weather right. Our “local” weather is mixed in with several other communities in our county, some of which are 20 miles north of us or about 1,000 feet higher in elevation. Considering that the temperature can vary about six degrees between our place and a neighbor who lives the equivalent of a block away but a little lower and closer the river, I figure the people in Atlanta or even Albuquerque really don’t get it.

But when various neighbors told us the last freeze would be “around Mother’s Day,” they were spot on: We had a hard freeze the Saturday before, and no other until October. When they said that the rains would start “on the Fourth of July,” they were close again. It started raining July 1 and pretty much kept raining for nearly six weeks. I have not asked about the need to tie weather events to well-known holidays, but if it works…

rain on patio
So then it really rained. Maybe because we were trying to pour a patio.

So, what do you do when your xeric garden gets rain, LOTS of rain? Well, most of the plants adapted just fine. They grew well and plenty of lovely annuals popped up from volunteer seeds. But guess what else happened? We got weeds. Every kind of weed known to man. Everywhere a weed could grow and some places I thought they couldn’t. In all of the gravel walkways, between rocks and pavers, inside cacti (those weeds are smart!). And pretty much all over the entire 4 acres.

These city folk did not yet have a riding mower; we had a lot of moving expenses and no grass worth mowing before July 1. Then the grass was too wet to cut most days. So by the time we got a mower to the back orchard, the weeds were up to my knees. We eventually conquered the mowing, but lost the battle in much of the garden. My thinking is that the yard and weeds had a year’s head start on us, and it will take us a little time to catch up.

weeds take over
Still raining Aug. 10. See the weeds in that front bed and all along the ditch bank in the background?

I also have been meaning to ask a neighbor what sort of event to expect on Thanksgiving. Maybe our first snow, though I think it might hit sooner. I just hope the snow doesn’t last for six weeks.