If you’ve always done your planting in spring, you may be surprised to hear that fall is for planting too.
Did you know that for many plants early fall is actually the best time to plant? And this is why: plant roots go into an active growth cycle in the fall with up to 80 per cent of the roots’ growth occurring then and continuing as long as the soil isn’t frozen. (Mulching the soil after planting will postpone soil freezing so root growth can continue as long as possible.)
Root growth is stronger in fall because the soil is warm and, since the air is cooler, plants require less water and are therefore less prone to transplant shock. By late summer, a plant’s top-structure has stopped growing so the roots don’t have to expend energy to keep the leaves nourished. In effect, fall-planting can help plants gain a full growing season in root establishment allowing them to be better able to withstand heat and drought the following year. Fall planting is also advantageous in that there are fewer pests and diseases to interfere with plant development.
Spring-planted stock, on the other hand, is slow to grow because soils are often wet and still cold from winter. Plants struggle to grow both leaves and roots. Hot weather brings even more stress because root growth slows dramatically when soil temperatures get too high. And while root growth resumes with cooler fall weather and plants will have had the entire growing season to get established before winter, many plants struggle through the first year after planting because of these stressors.
In our area, the most important criteria to take into account with fall planting is to plant early enough that roots have five weeks to ‘settle in’ before the onset of cold weather. That means late August to mid-September is ideal for fall planting; most container-grown trees, shrubs and perennials are good candidates for early-fall planting. Make sure that new plantings get at least one inch of water per week. Early fall is also the best time to plant or over-seed lawns because warm soils result in quick germination and establishment. Fall is the traditional time to plant garlic and spring-blooming hardy bulbs but it’s not as critical to plant them in early fall as it is for nursery stock.
It’s important to be aware of the hardiness zone of your garden area. Plants that are only border-line hardy for your zone are at greater risk of winter injury when not well established so either avoid planting such items until spring or use every precautionary technique possible to get them through the winter. Fertilizers are generally not required with fall planting but you can use a ‘root-boosting’ fertilizer which contains rooting hormone to help roots settle in quickly; apply an anti-desiccant (a light natural wax) just before the onset of cold weather to help prevent excessive moisture loss and apply mulch (but keep two to four inches away from stems/trunks) to keep roots growing as long as possible.
A visit to a garden centre in the fall will introduce you to a new palette of plant materials you may not have considered in spring. Plants with fall blooms, berries, and spectacular foliage colour will add beauty to your landscape in fall and into winter, as will plants with interesting bark or evergreen foliage.
-Harriet Hanna is a Shuswap gardener and an owner of Hanna Orchard and Garden Centre.
