Living Columns & Blogs

How do I best water plants to avoid under- or overwatering?

Washington State University Master Gardener David Simonson sets up a water drip irrigation system at the demonstration gardens at Hovander Park in Ferndale. Drip systems can help ensure adequate watering and reduce chances of blight.
Washington State University Master Gardener David Simonson sets up a water drip irrigation system at the demonstration gardens at Hovander Park in Ferndale. Drip systems can help ensure adequate watering and reduce chances of blight.

Question: I’m hearing conflicting advice on when to water plants. I know that I waste water when I water on a sunny day. But besides that, what’s best for my plants?

Answer: Any time a plant shows stress from lack of water, as evidenced by drooping leaves and stems, it’s the time to water. Better yet, water on a regular basis, before the plants are stressed. But be aware that overwatering is just as bad for plants as underwatering. Water deeply, but don’t create mud. And be aware that you cannot provide what is needed by just spraying with a hose.

Here in the Northwest, fungus is always lurking. That’s the other reason not to spray your plants with a hose. To protect your plants from fungus, try to keep water off the leaves. Contrary to popular belief, wet foliage is not susceptible to sunburn. It is susceptible to fungus, however.

The best way to water plants, including all ornamentals, trees, shrubs, and veggies, is with a drip system. It will help your water bill, too. It’s easy to use; kits come with everything you’ll need, and they’re relatively inexpensive. If you use a timer on your system, you’ll ensure that no matter what, your plants will be well and safely watered.

A note to tomato growers: Do whatever you can to keep water off the leaves of your tomato plants. Watering overhead, with a hose or sprinkler, splashes soil onto the lower leaves. Unfortunately a great deal of the soil in the Northwest contains the spores of the dreaded blights. Those who’ve experienced it groan when they hear the word.

Blight on tomatoes ruins both the plants and the fruit, usually just when those beautiful red orbs you’ve slaved over are just short of harvest.

To avoid blight altogether, make a plastic cover for your tomatoes; the occasional summer rain can ruin your tomato crop just as overhead watering can. And definitely consider installing a drip system.

An easy way to water plants that need extra water (newly planted or pruned, for example) is to poke a few small holes in the bottom of gallon jugs, and bury the jugs, leaving only the necks exposed, near the thirsty plant. They’re easy to refill, as they will slowly empty, giving water to your plants.

Q: My new yard is an open palette, ready for me to plant trees and shrubs. I’ve made a planting plan, decided what plants I want, but now I need to know the best way to actually plant new plants to ensure they do well.

A: Lots of research has gone into best planting methods. Here is what to be aware of when planting a shrub or tree: depth and width of planting hole. The hole needs to be at least twice as wide as the root mass but no deeper than the root mass.

Equally important is to straighten or remove any circling roots and direct the roots outward into the hole. Do not use any of the soil in the container the tree or shrub came in, and don’t use any amendments or fertilizer. Your tree or plant will establish more quickly and will be healthier and live longer if you follow these planting guidelines.

Q: I plan to grow many flowers and vegetables in pots as my soil is too wet. I’m working to change the drainage pattern in my yard, but it will take quite a while as it is a large and complicated job. Still, I want a season of some color and food this year. What should I know about planting in pots?

A: First, use large containers. They’re easier to keep adequately watered, and plants like to spread out in them. So put the empty pots where you want them to be and work on them in place. Saves your back!

Then, contrary to what you may have heard, do not use drainage rock or sand in your soil. Nearly a hundred years ago, scientists showed that water does not move easily from fine material (soil) into coarser material (rock or sand). Instead, make sure there are adequate drain holes in your planting container.

Large pots filled with soil are heavy. To lighten the weight, use a few empty and capped plastic bottles, like milk jugs, for example. Fill your planting pot one-third full of soil, then place the jugs and cover with soil.

Good luck with your new yard; you’ll be an experienced gardener when you’re finished!

Kathleen Bander of Bellingham is a life-long gardener. Her column will appear in The Bellingham Herald weekly through the summer growing season. If you have a gardening question you'd like answered in the column, please email it to For more gardening information online, go to