If you’re a vegetable gardener, chances are that your soil has taken a beating this winter. Even if you diligently mulch your beds, months of rain and freezing temperatures will inevitably take their toll. Rain tends to wash away organic matter and minerals like calcium, leading over time to depleted, acidic soil. Your soil just isn’t the same as it was a few months ago.
Late winter and early spring is the perfect time to do some yearly soil maintenance. By regularly amending your soil, you’ll ensure that this year’s garden is as good as last year’s.
Do some spring cleaning
It’s amazing how long it took me to learn this fundamental gardening principle: before starting your spring garden, give your beds or containers a thorough cleaning. Remove everything from your planting space, except for tidy sections of overwintering or perennial plants. By taking things down to a “blank slate”, you’ll have an easier time maintaining your soil and determining what to plant this year.
Test your soil
Get a baseline of your soil’s pH levels by using an at-home testing kit, available from garden supply centres. Test several spots throughout your garden, as things can be quite different even within the same bed. The ideal pH level for most vegetables is between 6.0 and 6.5. When soil is too acidic (alkaline soil is rare in coastal B.C.), plants will have a hard time absorbing nutrients from the soil, and your garden just won’t grow.
If your soil is acidic, add garden lime, available from garden supply stores, to your soil. Use according to package directions or sprinkle on a thin, even layer and rake it gently into the soil surface. You’ll then need to let your garden rest for at least three weeks (or, better yet, add lime in the fall so that it can break down over the winter) before planting to allow the lime to work its magic. Liming usually does not need to be done every year, but it’s worthwhile to test your soil’s pH regularly to make sure you’re in a good range.
If your garden is connected to the existing soil table, such as with dug beds or bottomless raised beds, consider testing your soil for heavy metal contaminants through a reputable lab. You’ll appreciate the peace of mind that comes with knowing your soil is healthy and safe.
Add an inch or two of compost, either homemade or purchased, to your soil every spring.
In a perfect world, we would all be making our own compost, but this can be difficult to achieve in an urban setting, so consider buying compost from a reputable supplier. Commercially available compost is processed at high temperatures and often has a finer texture that homemade urban compost. It can be raked into the surface of the soil as you would with lime.
Homemade compost often is often less “finished” than purchased compost. Remove large chunks and add it by double-digging under the soil surface. Do not use compost that is smelly, slimy, or not fully broken down.
As with adding lime, give your garden a couple of weeks to “cool off” after adding compost. This will enable the nutrients to incorporate into the soil and may allow pathogens to die off.
While animal manure can have a place in vegetable gardens, it also comes with risks, including e. coli and other pathogens. The University of Maine has published a helpful set of guidelines for using manure on vegetable gardens. If you decide to use manure, research your sources carefully. Ensure that the stuff you're using has been “aged” or “composted” and tested for pathogens, and, ideally, that it comes from antibiotic and pesticide-free sources. Never add fresh, raw manure to a vegetable garden. Dig manure under the soil rather than adding to the surface. You can also grow a healthy garden using vegetable-based compost.
Vegetable gardening takes a lot out of the soil. With the frequent plantings of fast-growing crops that most urban gardeners focus on, nutrients can get depleted surprisingly quickly. By doing some yearly maintenance, your garden will be off to a good start for spring. Caring for our soil, and giving it the replenishment it needs, will keep things healthy year after year.
Rebecca Cuttler is an urban gardening teacher, member of the Vancouver Food Policy Council and board member of the Environmental Youth Alliance. Join her on Roundhouse Radio 98.3 FM every Tuesday afternoon at 5:00pm for Fabulous Urban Gardens. She blogs about urban food gardening at http://abundantcity.net.