Cool- Season Vegetables
What to plant:
You can continue planting and harvesting many vegetables in the autumn by starting fast-growing varieties from seed or by purchasing transplants from local garden centres. Autumn is a great time to plant another crop of spring greens such as spinach, leaf lettuce, arugula, mustard greens, and mâche because they require cooler soil for seed germination and they mature quickly. Fast-growing root veggies such as radishes, beets, and turnips also thrive in cool conditions and take less than two months to mature. It is also a good time to plant onion sets and garlic cloves for harvest in late spring or summer of the following year.
When to plant:
To determine the optimal time to plant autumn crops from seed, you’ll need to do some math. Check the back of the seed packet for the “days to maturity” and then count backwards from the average date of the first hard frost in your area. Because the growth rate of your plants will slow as the days shorten, count back another week or two to determine your sow-by date. In most cases, you should stick with cool-season crops that mature in 70 days or sooner, unless you live in a climate with mild winters. If you’re growing frost-resilient varieties or starting from transplants, you’ll have a bit more wiggle room.
If you’re planting your seeds in a vegetable patch where you’ve recently harvested summer crops, you won’t need to re-till the soil. Just rake through it lightly to loosen the topsoil, and work in a bit of compost or other organic matter to help retain moisture. You can also repurpose the pots you used to grow summer annuals by filling them with cool-season edibles. Some container-friendly options include lettuce, spinach, kale, chard, radishes, and carrots (see Growing Vegetables in Small Spaces.) In the autumn, many garden centres sell cool-season vegetable seeds at bargain prices. Take advantage and buy more than you need because you can save the remaining seeds for planting the following spring.
Trees, Shrubs and Perennials:
What to plant:
Autumn planting of trees and shrubs offers a number of advantages over spring planting. The cooler temperatures are easier on the plants, so there is less chance for them to suffer from heat stress. When the air temperatures become cooler than the soil, new top growth slows, allowing plants to focus their energy on root development. The moisture from rains also helps trees and shrubs establish strong root systems.
Most deciduous shrubs can be successfully planted in autumn. Spring-blooming broad-leafed evergreens, such as rhododendrons and azaleas, also prefer autumn or early spring planting. In hot climates, autumn planting is ideal because the plant’s root system has more time to get established. In addition to planting new shrubs and trees, it is the best time to divide or move perennials that need more growing room, especially those that bloom in the spring or summer, such as daylilies, bearded iris, peonies, and garden phlox
When to plant:
Divide and move perennials at least several weeks before the average date of the first hard frost in your area so your plants have time to recover from transplant shock and establish new roots. For trees and shrubs, allow at least four to six weeks before the ground freezes to give them enough time to become established. If you wait until the tail end of the fall season to plant (November or December), you run the risk of poor root growth.
Most trees, shrubs, and perennials planted in the autumn are no longer producing new top growth, so they don’t need much pampering. After planting, focus on providing ideal conditions for root growth by keeping them well watered until the ground freezes. Also cover garden beds with several inches of organic mulch, such as shredded bark or leaves, to keep the soil warmer longer and to minimize damage from winter freeze-thaw cycles.