October Gardening

Putting your autumn garden to bed

Native honeysuckle fruit. Photo by Val Morton.

Autumn is here, and that means it's time for a final fall garden clean-up for the year.

When it comes to priorities, Butterflyway rangers (and garden-lovers) Hana Boye and Val Morton have a few tips to share, and the first is a piece of good news.

Leave the leaves

"We have all heard the phrase ‘Leave the leaves’," says Morton. "There are many good reasons to do less garden cleanup in the fall, rather than more. For example, many insects use plants stems to overwinter and for larval development. Others overwinter under fallen leaves. twigs and brush. All of these natural mulches provide excellent microhabitats for many organisms."

She points to the Xerces Society for Invertebrate Conservation, which explains the benefits the natural ecosystem receives from leaving behind a layer of leaves.

Morton says that autumn is also an ideal time to assess your garden and clear out invasive weeds including English ivy, periwinkle, morning glory, Himalayan blackberry and lamium.

The Magic of Mulch

In nature, mulch occurs when leaves, twigs and needles fall to the ground in the autumn and provide a cover over the soil around plants. Boye says that mulch helps to protect the soil from freeze-thaw patterns that can heave the plants out of the ground as well as helping to insulate plant roots.

Wood chips, rotten manure and compost along with fallen leaves can all act as mulch to protect autumn gardens. "Mulch can also add nutrients, to the soil which creates a healthy environment for soil microorganisms," Boye says.

She notes that it's advisable to wait until after the first hard frost before adding mulch to your garden. "Five to seven  centimetres of mulch is a good depth, and you should keep the mulch away from the stems of the plants to prevent rot.

Morton and Boye point to The Old Farmer’s Almanac, which can offer more information about mulching your garden in the fall.

Planting Perennials

But autumn doesn't have to be reserved for garden cleanup. According to Morton, it's also a good time to plant.

"The first half of fall is a good time to plant perennials because of the increased rain, cool temperatures and relatively bright skies," she says. "This allows perennials to develop a good root system before the winter so they are ready to go in the spring.

Morton says that experts suggest you can plant perennials up to six weeks before the ground freezes. "On average, the first fall frost in the Lower Mainland is November 11 and the last spring frost is March 19. This suggests that you should not wait much longer if you want to plant some perennials before winter."

She adds that while the leafy part of perennials dies back at this time of year, the root system continues to develop in the cool, moist autumn soil.

Boye wants to remind gardeners that fall-blooming native plants are producing their seeds now. For those interested in trying to germinate native seeds, she says this is prime collecting time.

While good germination rates can be achieved indoors, "most seeds from native plants need to experience winter conditions in order to know that winter is over and it is safe for them to germinate," she says.

Doing so indoors is called 'stratification', and information about this process can be found on the North American Native Plant Society website. But in nature, of course, this process happens outdoors.

Seeds can be spread directly onto prepared soil and covered with a thin layer of soil at about the same depth as the size of the seed, or they can be planted in containers outdoors and then put in the ground once they have germinated and grown large enough to transplant into the ground. The Alberta Native Plant Council has excellent information about outdoor seed germination HERE.

Happy autumn gardening!