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Putting the Garden to Bed: A Toronto Master Gardeners Guide

In fall, take cuttings of tender perennials such as this geranium (Pelargonium) called 'Happy Thought'. It's a fun way to save money and keep favourite plants from year to year. Photo: Helen Battersby

Putting the garden to bed for the winter is an annual necessity. This gardening guide describes the work that should be considered each fall. Much of this work will enable us to ensure that our ornamental gardens will survive the challenging conditions of winter.

 Lawns

Re-seeding is best done in early September. Keep newly seeded areas moist. After September the lawn needs a slow growth period to harden off for winter. Wait for spring if you missed seeding early in the fall. Top-dress the lawn with compost or a product such as a triple mix (loam, peat and well-rotted manure). Spread a fertilizer with a high Phosphorus number (middle number in formula). In Toronto, the best time to fertilize your lawn is the first week of November.

Rake leaves off the lawn before the snow falls. Leaves left on the lawn all winter will encourage snow mold. Chop leaves up with a whipper snipper in a garbage can or with a mulching mower. Collect leaves for your compost bin or bag them in dark garbage bags for composting, if there is not enough room in your compost bin. Poke holes in the bags to allow air and moisture and add a shovelful of compost or garden soil to activate the composting process.

Continue to mow the lawn until frost. Although it is recommended that you mow at a height of 2½ inches throughout the growing season, the last cut before winter should be lower, about 1½ inches. Mow the edges a second time. You could be looking at a bare lawn much of the winter so leave your lawn short clean and neat.

If your lawn is damaged by skunks or raccoons looking for grubs, replace sod pieces temporarily and repair in the spring. Spraying for grubs now is ineffective.

Annuals

Remove and compost annuals if bitten by frost but not diseased. Consider removing plant markers. Some gardeners refer to these as little plastic grave markers. Do not remove all annuals because some are actually tender perennials and may survive a mild winter, e.g.. dusty miller, pansies, snapdragons.

Some annuals can be over-wintered indoors. Take cuttings for houseplants from geraniums, impatiens and fibrous begonias. Lift tender bulbs such as dahlias, tuberous begonias, gladioli, and callas.

Harvest vegetables. Wrap green tomatoes in newspaper to ripen them or use them for specific recipes such as fried green tomatoes or green tomato relish.

Perennials

Cutting back the perennial garden allows you to aim for something between the scorched earth look and leaving all the plant skeletons. The main objective of fall pruning is to cut off diseased parts and avoid providing over wintering spots for insects and disease. Leave seedpods and flower heads that will provide winter interest or food for the birds. These can be cut down in spring. Examples of these are astilbes, grasses, sedums, Rudbeckia (black-eyed susan), Echinacea purpurea (purple cone flower).

Remove leaves if blackened and destroyed by frost (e.g. Hosta, Hemerocallis). Mulch around tender perennials after the ground has frozen. Mulch is not used to keep the plants warm but to keep them frozen in the spring sunshine, by minimizing the damage caused by heaving of the soil. Consider using the following as mulch – leaves (oak leaves tend to stay dry; maple leaves are best shredded), aged sawdust; conifer branches, hay. Freezing and thawing can cause the soil to heave and expose plant roots to extreme cold and drying wind. Raking fallen leaves onto your beds and borders can easily prevent this. The layer of leaves should be six to eight inches deep and anchored with branches; conifer branches are ideal.

Do not put diseased plant remains (e.g. parts affected with powdery mildew) in compost.

Roses

Cut back hybrid tea, floribunda and grandiflora roses to about 18″ to avoid wind damage and possible upheaval of roots in strong winds. After the ground has frozen, hill up the soil to cover the crown where the graft is located. Use friable soil left over from an annual basket or retained in a warm place (e.g. garage). Do not use manure or compost. Once the soil is frozen cover with more soil, damp sawdust, leaves or hay. Chicken wire or plastic collars can be used to hold the mulch in place and provide further insulation. Cut up conifer branches, laid around the crowns of roses, will also act as an insulator by holding the snow in place and minimize the possibility of rodent nesting in the mounds.

All shrub roses including David Austin roses can be cut back to about 2 or 3 feet. For climbing roses, secure or remove branches to avoid possible wind damage. Most miniature roses are hardy, but consider hilling up with soil.

Bulbs

Begin planting bulbs in September. Narcissus, allium and small bulbs should be planted by the end of September or early October. Tulips can be planted as long as the ground can still be worked before freeze-up. Plant in groups or clumps. Plant larger bulbs in uneven numbers for a more natural look.

Trees and Shrubs

Wrap trunks of young trees or fruit trees to protect from sunscald. Sun damage or south-west injury causes the bark to split exposing the tree to insect damage and disease. If severe, sun damage can cause the tree to decline or even die. Wrapping tree trunks will also protect against rodent damage. Remember to remove the wrap in the spring.

Evergreens

After freeze-up on sunny days during the winter months, warm air speeds up transpiration or loss of water, but the roots may still be frozen. Leaf desiccation commonly shows up in late spring as brown foliage. Desiccation can cause the death of a plant. To reduce the possibility of desiccation, water regularly and abundantly until freeze-up. If the weather is dry, water deeply once every seven to 10 days. An anti-desiccant can be sprayed on evergreen foliage but be careful to follow directions.

Layer fallen leaves around the base of evergreens. Consider the planting location and the need for protection. Wrap evergreens (particularly if newly planted) with burlap, if exposed to prevailing winter winds or salt spray.

Rhododendrons

Mulch with pine needles or oak leaves to keep soil acidic. Create burlap tents or ‘surrounds’, using stakes, for protection during winter. Ensure that the burlap does not touch the foliage.

Soil Improvement

Top-dress around perennials using organic material such as compost, shredded leaves or well-rotted manure. If using leaves as a mulch, consider leaving this on the beds in spring. This organic matter will soon decompose and add nutrient to the soil. Oak leaves are the exception because decomposition typically takes a long time.

Create new beds by removing sod and all weeds from desired area and top dressing with organic materials. Loosen soil to a shovel depth, but don’t turn it over – you will disturb the natural soil profile that’s built up over many years. Leave over the winter for frost to break down clumps.

General Clean-up

Other general garden clean up activities might include:

  • Clean and put away furniture, pots, hanging baskets.
  • Store clay and ceramic pots inside.
  • Drain all hoses and store inside.
  • Turn off outside water sources.
  • Window boxes left in place can be used for Christmas decoration.

Cleaning Tools

Clean, sharpen and oil all garden tools. Lawn mower and hedge clippers may be best left to the professionals at your local hardware or garden centre. It is important to get the right angle on the blade. Paint handles bright colours so you won’t lose your favourite tools.

References

Time-Life Books Inc. Complete Guide to Gardening Landscaping. New York: St. Remy Press, 1991

Hole, Lois. Lois Hole’s Perennial Favorites. Edmonton, Alberta, Canada: Lone Pine Publishing, 1995

Date revised: January 2012

Produced by the Toronto Master Gardeners, these Gardening Guides provide introductory information on a variety of gardening topics.

Toronto Master Gardeners are part of a large, international volunteer community, all committed to providing the public with horticultural information, education and inspiration.  Our goal is to help Toronto residents use safe, effective, proven and sustainable horticultural practices to create gardens, landscapes and communities that are both vibrant and healthy.

If you have further gardening questions, reach us at our gardening advice line 416 397 1345 or by posting your question here in the Ask a Master Gardener section.  To book Toronto Master Gardener volunteers for talks, demonstrations, advice clinics, or other services, please contact us at 416 397 1345  or bookamg@torontomastergardeners.ca.