Seriously - When do I water?

As professional Landscapers, we are often asked how much water someone's plants need - a fair question, to be sure, but not a simple one. More often than not, the response people get is not as precise as they expect.

landscaping gardening questions

They feel we should be able to drop a number on them. "Your Schubert Chokecherry needs 36 litres of water per day," people expect. What they get is a barrage of questions about the species of plant, where it's planted, what neighbourhood the property is in, whether it's planted in the sun or shade or both (and what time of day it's in shade), how old it is, what's planted around it, whether it's a windy or sheltered location, and what kind of condition it's in.Truth is, those factors can radically change your plants' water usage, so it comes down to watching the soil.

Trees and shrubs: 90% of a trees roots are within a foot of the surface, and almost all the living root tips (where water and nutrients are actually absorbed) are at or beyond the furthest extent of the tree's branches. Pick a spot a foot or two from the furthest branch tip and dig a small diameter hole about 8 inches deep. If the hole is dry all the way down, your tree could be getting desperate. If the soil is soggy, the roots may be drowning. Whatever the weather conditions, you should be watering enough that the soil pulled from a test hole will hold together when squeezed, but still crumble. In general, a few hours of watering every two to three weeks will keep most trees happy in all but the hottest, driest conditions. If your tree is newly planted, water more frequently for less time - twice a week for half an hour each time should be enough, but watch for droopy leaves or brown spots.

Lawns: I didn't have to water my lawn until early August, just because we had so much snow all winter, and it wouldn't stop raining. The City of Calgary tells residents that your lawn doesn't need more than an inch of water a week, and they're right for most lawns. If your lawn is less than two seasons old, watering two inches a week will help the roots grow a little deeper into the soil, which makes for more drought-resistant grass. Oddly, mowing makes a big difference - keep your lawn between 2 and 3 inches long and it creates a micro-climate between the blades of grass. The extra length shades the roots and cuts out the wind, allowing the moisture to stay in your lawn instead of being wicked off by the wind.