Usually in summer, the biggest problem is keeping our gardens from drying out in the hot sun. But what about when there’s too much rain?
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July was a crazy month for rain here. It was bad enough in Toronto where I live, but we had nothing on poor Ottawa: Canada’s national capital smashed through a record that had stood since 1899, with 291.8 mm. That’s some serious rain.
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Heavy rain, especially over an extended period, can cause serious stress to gardens. In fact, it’s worse than drought in some ways. It can have the same effect, in a manner of speaking, as overwatering a houseplant — but on a garden-sized scale.
Water pouring onto the soil can literally drown roots, by filling in air pockets; and of course, plants need air as much as they need water. As moisture seeps downward, it washes away nutrients, starving plants of needed minerals and other chemicals. And fungal disease, mildew, and pests, especially slugs and snails, thrive in wet conditions.
The problem is most serious if the soil is compacted, or if it’s clay-based, which describes much of the glacial-till-based soil in southern Ontario. Pounding rain can quickly turn it into hard cement. Compacted soil presents several hazards: everything from reduced runoff to suffocating plant roots and starving the plant of nutrients.
Overgrown gardens are especially vulnerable to excessive rain. Many plant diseases, like leaf spot, powdery mildew and rust, are communicable; they can spread from plant to plant until the whole garden is infected. There are also diseases that spread underground through the roots that are similarly damaging.
Hot, wet summers like this one do test the mettle of us city gardeners. But once the sun comes back out — and it will — certain good practices, some of which you may already be doing, will help prepare your garden to weather the storm.The best remedy (and surprisingly enough, it’s good advice for most garden challenges) is good overall maintenance. Regularly condition your soil with compost or organic matter, and cover beds with a couple of inches of mulch. These two elements both protect against the compacting effects of rain and encourage healthy soil flora and fauna, which in turn help keep the soil crumbly and loose.
Avoid working the soil when it’s wet. Let it dry out, then if compaction is a problem, you can lightly fork over the soil or stick a garden fork in the spaces between plants to re-introduce some air. Aerating your lawn can be helpful too. (There are hand aerators that you roll across your lawn like a push mower, or you can hire a lawn company to do it for you.)
Stake or otherwise support plants with heavy blossoms, like peonies, hydrangeas and lilies; there’s nothing sadder than seeing a beautiful Stargazer or Casa Blanca lily face-forward in the mud.
Keep garden beds tidy by removing dead plant matter and other detritus, and avoid overcrowding or letting plants flop over onto each other. Maintaining good air circulation between plants not only encourages growth, but helps them dry out faster after a rain.
The best time to prune or divide your garden plants is generally spring or fall, but you can do either one at any time during the growing season except really late in the fall. If the soil is dry enough to perform these tasks, don’t put them off.
Longtime gardeners know that it’s impossible to accurately predict summer weather too far in advance, but The Weather Network says August could be just as hot, but a bit drier.
