As you can imagine, there’s not a lot of planting going on in January and February—but it is a great time to start stocking up on your supplies. Look for a quality grow lamp, heat mat, seed starting mix or starter kit, and of course, your seeds! When it comes to seeds, you may want to purchase them early before popular varieties sell out.
January: Onions and strawberries can be started indoors.
February: Leeks, Lettuce, Eggplant, Onions, Peppers (late Feb), Asparagus (late Feb) Strawberries can be started indoors.
If you’re starting seeds, March is the time to get them growing. Peppers and onions, which can take a long time to mature, can be started indoors in early March. Start tomatoes and cruciferous vegetables (like broccoli, cauliflower, and cabbage) artichokes, aspargus, in late March to early April.
If you want to start annual or perennial flowers indoors, you can start the seeds in March or later in April depending on their days to maturity—your seed packet will indicate how early to plant each variety.
April
In April, the weather is continuing to warm up gradually but we’re not nearly out of the woods. Continue to nurture your seedlings, and don’t forget to thin seedlings that share a growing vessel. (This means you’ll need to snip off the weakest seedlings in each vessel and leave the strongest one.)
Mid-April is the best time to start cucurbit seeds like cucumbers and zucchini. You can also start annual and perennial seeds that require less time indoors (i.e. 6 weeks) around this time. Try nasturtiums—they’re pretty and edible!
Once the ground is workable, which can be as early as late April and as late as mid-May, it’s a fine time to plant trees and shrubs if you can’t wait until fall!
Through most of May, you’ll be tempted to get planting—but don’t get too excited! If you absolutely must get something in the ground in early-to-mid-May, direct-seed cool-weather crops like asparagus, beans, and root vegetables which can tolerate a light frost. Otherwise, use the month to begin slowly hardening off your seed starters and start making trips to our garden centre in Guelph to stock up on flowering annuals and gardening supplies. You’ll get the best selection if you arrive early in the month and keep them indoors in a sunny, sheltered area until it’s time to plant.
The risk of frost has usually passed by Victoria Day, making it among the most popular gardening weekends of the year! The weekend before Victoria Day (which lands on May 24 in 2021) is a great time to plant spring annuals, summer bulbs, and transfer most of your baby seed starters into their permanent homes in the garden. Veggies that are particularly cold-sensitive, like tomatoes and peppers, may be best off waiting an extra week when the weather is a touch warmer and more reliable.
Late May is also a suitable time to divide perennials; dig them up and divide them using a sharp, clean knife.
In June, the soil is warm and it’s still a lovely temperature for planting! From early June on, you can direct-seed warm-season veggies, finish planting tomatoes and peppers and continue to plant starter plants from our nursery, including annuals, perennials, and vegetable plants. Keep an eye out for weeds and apply a layer of mulch to new plantings to keep their roots cool and moist.
In July and August, temperatures are a little hot for planting. If you do plant, you may have better luck with shady areas or containers, which are easier to safeguard from the blazing summer sun. Otherwise, focus on keeping your other plants well-watered and weed-free. Consider implementing an integrated pest management program (IPM) to control pests while maintaining a healthy ecosystem.
In September, planting gears up again! You can plant another round of cool-season crops to squeeze out one more harvest before winter. By late September, conditions will be just right to start planting fall bulbs. Decorate your garden beds and containers with colourful garden mums and cool-weather annuals for a little fall magic!
October brings the beautiful combination of cool weather and warm soils—the best time for planting trees and shrubs all year. Consider planting evergreens to set your landscape up for some lovely winter colour. You can continue to plant them into November, effectively until the ground freezes—but don’t forget to keep watering them, even when it gets cold!
In mid-October, you also have a great opportunity to plant garlic for a summer crop next year.
December marks the end of the gardening calendar for Southern Ontario, leaving you lots of time to rest, recharge, and relax. But if I know anything, it’s that we gardeners will be dreaming of digging back in by the time January comes around!
