Do you want to grow a garden?
There are many reasons to dig in, including to:
- Eat delicious, fresh, local, organic food.
- Save money and avoid wasteful packaging, e.g., a small urban lot with less than 0.024 hectares (0.06 acres) in production might enjoy yields worth $3,500 to $6,000 per year!
- Enjoy physical and mental health benefits of digging in the dirt (soil microbes).
- Help pollinators.
- Take climate action. Did you know “greenhouse gas emissions can be cut by 2 kilograms for every kilo of homegrown vegetable when compared to the store-bought counterpart?”
How do contaminants get into your garden?
- Through rain.
- Wind moves dust from the street.
- Vehicle emissions (backyards are less at risk than front yards or boulevard gardens).
How to prevent or reduce risks of soil contamination?
- A neutral pH (6.5-7.5) can immobilize or bind lead, zinc and cadmium. Many metals are more bioavailable in acidic soils.
- Leaves are great for mulch, providing a protective blanket come fall and winter. They’ll help insulate the roots in winter and keep them cool in summer. But don’t collect leaves from roadsides.
- Don’t plant edibles within three metres of buildings or busy streets where lead levels are highest.
- Don’t make garden beds from chemically treated wood like railroad ties or pressure-treated lumber.
Five planting strategies
1. Practice “no dig”
Digging and turning destroys soil structure and its living community. The top 10 centimetres of soil is home to active microbes, worms and more that you’ll need for a successful garden! Linda Gilkeson, author of Backyard Bounty: The Complete Guide to Year-Round Organic Gardening in the Pacific Northwest, shares the harms and risks associated with deep cultivation:
- Breaking up important fungal mycelia. (Did you know mycelium is one of the largest living organisms on Earth?)
- Killing worms.
- Burying microbes with less oxygen and carbon dioxide exchange.
- Bringing up weed seeds to germinate.
- Breaking up the capillary flow of water to the roots from below.
Plant seeds and seedlings in the soil and organic matter, leaving the digging to worms.
2. Try intensive gardening
Neat row-by-row planting no more! Grow more food in less space with less work with these intensive gardening techniques:
- Create permanent garden beds to avoid trampling.
- Add lots of compost for a slow release of nutrients, to hold water and improve the soil.
- High-intensity mixed planting — use the entire surface of each bed.
- Succession planting — stagger plantings to extend the growing season (e.g., plant carrots on Canada Day!) and replant gaps after harvest.
3. Crop rotation
For farm crops, rotation is a way to manage soil fertility. But for home gardens, adding compost is the best way to add nutrition. Rotation can be helpful to avoid soil-borne root diseases. A few facts to get started:
- All veggies need nitrogen. Leafy greens and those in the cabbage family need it the most.
- Peas and beans are nitrogen fixers! Use legumes to increase nitrogen levels in the soil for the next crop. Nitrogen-fixing species (legume family) provide this nutrient to other plants and microbes in their immediate vicinity.
- Root veggies need potassium.
- Fruits like phosphorus.
- Rotate based on plant families since pathogens are host-specific.
- Rotate crops that are heavy feeders like garlic, squash and tomatoes. They deplete the soil.
- Most at risk for root diseases are the onion family and potatoes (nightshades).
- A short rotation (a few months) is needed between carrot family crops to prevent carrot rust fly.
4. Try intercropping
This means growing different crops close together at the same time to improve yields in a small space. And if your climate allows, plant winter crops into summer plantings. In some cases, it’s choose a “canopy” and an “understory” crop to co-exist. Examples include:
- Alternate rows of radishes (an early crop) with carrots.
- Fall brassicas (e.g., broccoli, cauliflower and cabbage) with cucumbers (as long as they’re not shaded completely).
- Lettuce with any crop that gets larger, later in the season.
- Thread late-season squash vines between mature plants (or send them to ramble and spill into non-garden spaces).
The Permaculture Research Institute suggests:
- Avoid plants from the same family in the same grouping.
- Choose plants with similar water needs.
- Choose plants with different root systems (to avoid competition underground).
- Consider how plants might affect each other’s sunlight (e.g., “nurse” plants provide shade and moderate the microclimate for new germinants).
- Combine plants with different growth rates so they won’t interfere with each other at the most crucial points of development.
5. What about companion planting?
While popular on the internet, it lacks a scientific basis.
Linda Gilkeson explains: “Some insect-repelling compounds in herbs are used as repellent pesticides, but the effect occurs when the essential oils are extracted and used as a spray — not while the plant is simply growing in place. Pest insects have very sophisticated, accurate abilities to detect their host plants and usually have no ability to ‘smell’ irrelevant plants that are not their hosts.
Companion planting the right flowering plants is effective to attract beneficial insects to a crop; interplanting attractant plants has lots of scientific research to support it and is widely used in certain horticulture crops (e.g., lettuce in California and strawberries in Ontario).”
Check out other garden myths busted by Linda Chalker-Scott of Washington State University.
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