Watering Stressed and Dry Gardens

I have spent a lot of time talking with clients about watering this year. Years like this are not as easy as turning on the irrigation system or putting out a sprinkler for a few hours.  

We were in ‘Abnormally Dry’ to ‘Severe Drought’ by mid-Summer in many parts of New England with a few pockets of ‘Extreme Drought’ (US Drought Monitor for explanation). We received some legitimate rain in August, and then went back to the same dry pattern. The Drought Monitor shows us largely out of drought currently, but I bet when it is updated later this week, we will start to see it creeping back in.  This is the third time in five years that we have experienced drought in some capacity, and it is stressful for our plants, large and small.

I am like that old guy who pays way too much attention to the weather and yells at the kids to ‘GET OFF MY LAWN’, but you need to pay attention to the weather, or read the newsletter of someone who does, to keep your gardens happy. Most people don’t realize that we haven’t had meaningful rain for a month. Water is critical to the health of your plants, and how to water can help people save money, time, and their plants.

I have seen a lot of plants suffering this year, and if you have plants that don’t look great, the easiest test is to dig down 6″+ in the bed and see what the soil looks like. When I have been doing this while visiting clients, the result is usually dry, crumbly, dusty soil.

Now, some plants like and thrive in this situation, think native upland plants like (Juniper, Ninebark, St John’s Wort, Chokeberry, Butterfly Weed, Coneflower, Anise Hyssop) or non-natives (Sea Holly, Lavender, Sedum, Salvia, Paniculate Hydrangea, Beautyberry, Abelia, Spirea). However, many plants, even native plants more used to moist soils, need supplemental water during these times.  

As a quick aside, if you have a mixture of plants in the same beds with different water needs, the fall is a great time to rethink your spaces and do some transplanting.  This means that in the future, you can focus supplemental water in beds that need it rather than wasting it across all of your beds.

OK, so you dug in and found dust in the hole, how do you get moisture back in the root zone of your plants. As I have talked about previously, people have a tendency to underwater in these situations, only adding enough water to penetrate the top couple of inches. Also, many soils that dry out can resist absorbing water. You may notice this when you try to water dry plants and it is hard to get water to penetrate.

The best solution is long, light application of water that has a chance to infiltrate without running off.  If you have an irrigation system or just a garden sprinkler (Aqua Joe), these need to run for a long time.  The question is how long. The answer is multiples longer than you might think.  The common rule used in gardening is that a garden needs about an inch of water a week from rain or irrigation.  That is a general rule that doesn’t work for all plants, but is a good place to start.  If you have irrigation for your garden beds or a sprinkler that you move around, turn it on and place one or a couple of flat sided receptacles like an empty can of beans or tuna fish around the spray area.  How long does it take your sprinkler to put an inch of water in the receptacle? 

I’ll wait…

I bet it was longer than you thought.  Was it 45 minutes or 90 minutes? Go back to your recently watered bed a few hours later and dig another hole 6″+ and see how far the water penetrated.

I’ll wait, again…

That didn’t go as deep as you thought, and with all the surrounding dry soil, the fact that it is close to the hot surface and thirsty plants, the moisture will be gone in no time.

Now that is how much water you need to apply every week to a garden that already has a good base of moisture.  If your garden is showing stress with perennials, shrubs, and trees (do you have leaves coloring or falling already), then you need to add multiple inches of water in the short-term (think a couple of days) to rehydrate your garden.  It is hard to say how long as every bed has different soil, sun exposure, plant material (big trees within 20′ will constantly suck moisture out of the soil), but use your shovel and dig a hole again.  Go deeper to see how far the water is penetrating. It may take three, four, or more inches to get good moisture back in your garden and then repeated the next week.

Wow, watering isn’t easy, and there is no formula.  You need to get in tune with whatever system you use to add supplemental water to your garden. If there is one thing that I say all the time, it is “water less often and longer.” Short watering every day or other day mostly evaporates and make roots come to the surface for water.  This makes plants (and lawn) less drought tolerant and susceptible to heat and drought. Most people would never imagine watering with a sprinkler for 4 or 6 hours, but see how much water it delivers. Over time, it will save you money (water and plants) if you keep your garden properly watered. Last summer was so wet, that this wasn’t a problem, but with several droughts in recent years, we are seeing the results in our large shade trees and established plants that are stressed, succumbing to disease, and declining.

Watering is part science and mostly art. Every situation is different and find out what is right for your specific garden beds. I know many of you have to deal with water restrictions. Rain barrels and underground cisterns can help you preserve rainwater to supplement during these dry periods. 

While we typically get rain in the fall, it can be dangerous to go into Winter with dry soil and stressed plants.  The results can be catastrophic, so make sure you get some good moisture in your soil this Fall.

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