Thursday, July 14, 2011

How to water plants

In the last five days I've put almost 136 L of water into my garden, not counting the lawn. Now I think I should be able to water less for a while, because most of the planters are saturated. The morning glories and pumpkins are always thirsty, because their planters are too small to have any reserve, but the others can hold water for some time.

This is where I get my information on watering:

"You need to allow water to soak deep into the soil, to encourage roots to grow deeper. Shallow watering makes for shallow roots, and when the soil surface dries out, the roots do too. Soil always dries at the surface first, so plants with deep roots need watering less often... More water less often is better than less water more often."

Lois Hole, Lois Hole's Perennial Favorites, p.44.

You people don't know Lois Hole, but she was the Lieutenant-Governor of Alberta for a while and a fantastic gardener. She and her husband and sons ran one of the largest garden centres in Alberta and she wrote lots of books and newspaper columns. So if she says so, she probably knows what she's talking.

It's pretty obvious anyway. Roots go looking for water. If there is some deep in the ground, they go deep. Deep roots hold to the ground better and have access to more water. You don't even have to get told to see that it's obvious.

However, that's for in-ground gardens. Planters lose moisture from the top and bottom, and if you use clay pots, through the pot as well. So I've been phasing out the regular old planters with a hole in the bottom, and buying only the new style with a false bottom that catches the excess water without giving it a huge surface area to sit in the sun and evaporate. Only planters 0 through 3 are the old style, all the rest have false bottoms. But even so, the soil isn't necessarily saturated just because there is water in the bottom of the pot. Most of my planters reabsorb the excess water very quickly, because they use up the water that's in the soil. When they stop absorbing, they're saturated.

Thus, the maydays and geraniums are not getting watered every day, because they're not using up their water. Even though they're sitting in full sun in a heat wave, the surface of the soil is still moist, so I know they have reserves. The morning glories and pumpkins are getting watered several times a day because the planters aren't big enough to keep any reserves and they keep sucking up the water endlessly. I've never got to a point with them where they wouldn't take any more water.

The one thing that gives me pause is my lemons. Last time I repotted them, they had tiny shallow little roots, so clearly they need more water, but on the other hand, they never want any, and as a species they actually don't like a lot of water. So they rarely get any water, because they're not asking for any, and then they end up having root problems. However, as long as they're still alive, there's hope.

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