The science of watering your plants
Class, we’re going to delve into something you probably thought was kindergarten horticulture.
It has to do with watering your plants, and apparently a few of you skipped school a few days because I see you doing things wrong. We’re going to go back to the basics and explain water and how your plants need and use it – and how you should supply it.
It’s never too late to learn, and with temperatures hotter than Helotes, it’s high time that we did.
The perfect soil consists of 50 percent solid matter (soil particles, organic matter, etc.), 25 percent air space and 25 percent water. Plant roots have to have oxygen to survive, which is why you want to plant gardens in raised beds. They ensure good drainage during wet seasons. But you also want to keep the soil moist at all times.
Soil dries from the top. That’s not my most profound discovery. It’s where the wind and sun make direct contact with the soil and wick out the water. But, should you water daily so that top layer of soil is consistently moist? In most cases, no. Let your soil dry just a bit so the plants’ roots will grow deeper, seeking water farther down in the ground.
This is the shortfalling of people who stand on their lawns and “sprinkle” the grass or the flowers. That kind of irrigation is equivalent to taking just a sip of water when you’re really thirsty. You want to wait until the soil begins to dry to 2-3 inches, then soak the soil deeply. An exception would be with new seedings of turfgrass until the lawn can get its roots started. You may have to water the new grass every morning and evening for a few minutes to get it established.
Newly planted trees and shrubs require TLC. These plants have been grown in lightweight planting mixes to cut down on labor and shipping costs. Those soil mixes dry out incredibly quickly in summertime temperatures. What you must remember is that all of a new plant’s roots will be in the original soil ball until the plant gets established and starts to send out new roots. That’s going to take a couple of years, and during that time you’re going to need to water those plants by hand.
You’ll need to use a water wand and water breaker or bubbler, water turned on pretty much full force to deliver as much as 5 to 10 gallons to each new plant every couple of days from now into late fall. You just have to do it. Drip irrigation isn’t going to suffice. Those gimmicky water bags won’t do it. Lawn sprinklers certainly won’t do it. You need to do it!
Learn to “read” your plants’ water needs. Each plant species you grow will have its own way of telling you when it’s starting to need water. Most of us think of wilting as the prime symptom, and for some plants it is. But some plants really don’t wilt. Their leaves change colors. St. Augustine goes from lustrous bright green to dull, olive green (its blades also fold.) Asian jasmine and most of the hollies also turf drab olive green, but if you wait that long you’ve probably lost expensive hollies or big parts of the jasmine.
Tomatoes, however, may have the most curious indicator of moisture stress. It’s a malady called “blossom-end rot.” The ends of the tomato fruits that are farthest from their stems are also the first places to get dry and the last places to get water (farthest from the roots). When a tomato plant doesn’t get enough water, the far end of the fruit develops a browned, sunken area and the entire fruit is basically ruined.
Moisture stress manifests in many ways. Wilting is certainly one of them, and blossom-end rot is another. But leaf yellowing and dropping are the most common with fast-growing, large-leafed shade trees in summer. Types like fruitless mulberries, cottonwoods, silver maples, empress trees, catalpas and even pecans and lacebark elms will start dropping leaves by early July. They can’t pull water through their roots, trunks and limbs fast enough to meet the needs of all the leaves they produced back when the spring was cool and moist. They start shedding leaves, generally the oldest, lowest ones first.
You’re also likely to encounter edge and tip burn with some of your plants, especially if you’ve let them get too dry between waterings. As with the tomatoes, it’s going to show up on the points farthest from the roots. I always compare it to circulatory issues we humans face. For us they appear in our fingers and toes, earlobes and nose. For plants, it will be at the tips of the leaves and around their edges. If you see yellowing or browning exclusively in those areas, you know that moisture stress is the cause. Then all you have to do is figure out what might have caused it (root damage, trunk damage, too much fertilizer, too dry, construction injury – and the list goes on and on).
When the subject turns to watering your plants, give it plenty of attention. You determine their destiny, and you need to be thinking it through. And now you know how to do it!
You can hear Neil Sperry on KLIF 570AM on Saturday afternoons 1-3 pm and on WBAP 820AM Sunday mornings 8-10 am. Join him at www.neilsperry.com and follow him on Facebook.