When to plant perennials *


With fall here, I think I’m supposed to be planting perennials that will then be in the ground ready for spring. Is this correct? I’m completely confused; there’s so much information out there but so much of it is conflicting.

FYI I am thinking of the front yard, which is quite small i.e. 10 or so feet by 18 or so feet, in which we have been growing vegetables (tomatoes, peas, radishes, carrots, corn, cauliflower, some melons) and annuals in a bed of triple mix that’s about 12 inches deep. Some of that crop has really had it’s day (melon, radishes) some is still coming up (tomatoes) and the flowers are doing kind of OK. Am I supposed to rip this stuff out to plant something else?


Perennials can add pizazz, colour and variety to your landscape and if you plan your garden carefully you will have something in flower throughout the entire growing season. You will also have the  benefit of attracting hummingbirds, butterflies, bees and other pollinators to your garden.

You can plant container-grown perennials anytime you can work the ground. Ideally, the best time to plant perennials is in the early spring since the plants will have time to become established before the hot weather begins. You will also find the best perennial selection during the spring months, especially if you are looking for early spring blooming varieties.

Perennials can also be planted in the fall as long as there are three to four weeks of good growing weather to develop strong healthy roots before the first hard frost.

It is strongly recommended you use a starter fertilizer at the time of planting for all new transplants.  Choose a fertilizer that is high in phosphorous (middle number), such as 10-52-10, this will encourage the development of a strong root system which is necessary for healthy growth and production.  It will also help prevent transplant shock. You can continue to use this fertilizer throughout the first growing season.

Covering the ground around your plants with a layer of mulch will help conserve moisture, prevent erosion, slow weed growth, moderate temperature, prevent crusting of the soil surface, and protect against soil compaction. Organic mulches are ideal because they insulate the soil, reduce evaporation of water and, add nutrients to the soil as they break down.  You can use different products for mulching which include compost, manure, bark mulch, leaf litter, straw and other materials.

Make sure to keep your perennials well watered for the first couple of weeks after planting. Then water when the soil below the surface feels dry to the touch. Don’t keep the soil soggy, which can cause rotting.

Deadhead, or cut off, faded blooms. Before winter arrives, prune the plants to 6 inches above the ground and cut back on your watering. If you live where the winters are warm, reduce watering to about once a month.

You may wish to refer to our  Garden Guides on perennials for various light and soil conditions before you head of to the garden centre:

Perennials for Sandy Soil: A Toronto Master Gardeners Guide

Drought Tolerant Perennials: A Toronto Master Gardeners Guide

Perennials for Shade in Dry or Moist Areas: A Toronto Master Gardeners Guide

Long Blooming Perennials: A Toronto Master Gardeners Guide

Native Plants for Shade: A Toronto Master Gardeners Guide

Including flowers/ perennials in your food garden is a good idea. Not only does it look fabulous, it will attract beneficial and pollinating insects, boosting yield and helping to reduce insect pests. However, in reality it’s not always easy to achieve an acceptable aesthetic without careful design, plant selection, and attention to each plant’s growth habit and needs.

It is important to remember to choose perennials that thrive in the same growing conditions as your edibles. For most vegetables, like corn and tomatoes, that means at least 6 hours of direct sun.

Good Luck!