Some of it is learned by trial and error with specific plants. But there are some essential principles to watering well:
- Water deeply when you water.
You’re better off to water a large quantity, infrequently, than to water a little bit more often. Plant roots will grow to where the water is. If you water in small amounts the roots grow close to the surface, where the moisture is. Then if you don’t water as often suddenly for some reason (e.g. you go away for the weekend) the top bit of soil dries out and so do the roots of your plants. But water thoroughly, so that it really soaks into the soil, not just into the top inch of soil, and the roots of your plants will be deep. Then if there are periods of drought they’ll be in moister soil and better able to withstand those conditions. If I’m watering a potted plant my general rule is to water it until the water runs out the drainage hole in the bottom of the pot (if your pot doesn’t have a drainage hole it’s not a pot, it’s a pot cover. You need to transplant your plant into a pot). When watering plants in the ground don’t be too quick to move your hose to the next spot, or afraid to run back to the rain barrel for another watering can (or three) full of water.
- Don’t overwater.
Unless they’re bog plants, most plants do not like to have their roots sit in water. They can rot out and suddenly you’ll find yourself standing there with the wilted top of a plant in your hand and a bit of mush in the ground where the roots used to be. Overwatering can easily cause just as much damage as not watering at all. The ideal is to give your plants the amount of water they need—no more, no less. Let the top inch or two of soil dry out between waterings, then water deeply.
Another reason not to overwater is that it’s wasteful. Water is a scarce resource that we must steward well. Plants bring many benefits to the environment and to us, so there is certainly a strong case to be made for providing them with the water they need. But in areas facing water restrictions it is wise to migrate your garden over time to plants that don’t require a lot of water, such as succulents.
We should also realize that we often coddle our plants with more water than they really need. In the first year or two of becoming established, perennials and young trees certainly do need supplemental watering in my climate. But once they’re settled in, unless there’s an extended hot and dry period, they don’t need to be watered by a human all that often. There are always exceptions (including plantings in areas under large trees where the rain doesn’t filter down), of course and remember that plants in pots always need to be watered by a human hand (or irrigation system).
- Water in the morning if you can.
Watering in the morning gives your plants time for any water on the leaves to dry off before the heat of midday sun hits (all those little droplets can act like a magnifying glass). Watering during the middle of the day can burn your plants. Also, much of the water will evaporate before it has time to soak into the soil. Watering in the evening means your plants stay damp all night—it creates a nice damp environment for all of the critters that like to chew on your plants—unless you want to host a nightly party for earwigs, slugs and snails, this is to be avoided.
- Direct water at the base of your plants, not the leaves.
If you’ve ever been taught how to use a fire extinguisher you’ve been told to aim for the base of the fire, not at the top of the flames or at the smoke. In a similar manner, point your hose or watering can at the soil around your plant. The roots are the primary part of the plant that takes in water, not the leaves. Also, getting the foliage wet can lead to the spread of diseases. I know that when it rains the foliage gets wet too—but when mother nature does it, it’s different than when you and I do it. And even mother nature’s watering can cause problems with if it happens too often—we had a very wet summer a couple years ago that caused a lot of disease problems on the foliage of my tomatoes.
If you can manage it, you’re better off watering with a hose (I like to use a long wand sprayer) or a watering can instead of an overhead sprinkler. Drip hoses are also good, but some are more effective than others; be prepared to leave them on for a good long time as they are designed dribble out a small amount of water over an extended period of time .
I fully understand that life gets in the way sometimes, and you have a choice between watering your garden at 9 o’clock at night in the one hour you have before you head to the airport or not watering them at all until you get back five days later (with a heat wave predicted for the entire time). I’d choose to water at night then too. But it’s not something I’d make a habit of, and I’d be aware of the consequences.
- Don’t rely on rain to meet all of your garden’s needs.
“The gardener looks on the rain as a gift. The gardener does not depend on the rain,” is how my garden mentor phrases it. Your zinnia or tomato or apple tree doesn’t care if it was supposed to rain last night or not—it will only respond to the lack or presence of water. “You have to water the flowers you want to grow” is a saying attributed to author and speaker Stephen R. Covey. He certainly meant it metaphorically, but the literal interpretation is spot on. If you want your garden to be fabulous you’ve got to take care of the needs of your plants; sometimes that means providing them with water.
Those are my essential principles for watering the garden. Do you have any others? Please let me know by leaving a comment below.
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