Halton Master Gardeners
Overwintering Your Vegetables and Plants
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Email helpline: haltonmastergardeners@gmail.com
Website: www.haltonmastergardeners.ca
Follow us on Twitter @Halton MGs
Why overwinter?
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Fun and easy!
Saves money
Indoor plants improve our well being; clean the air and cheer us up
Work of caution: Be aware that some plants are poisonous to cats and dogs and children! The Ontario
Veterinary Association posts a list of potentially toxic plants
What plants to bring in?
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Any tropical or tender annuals such as begonia, geranium, coleus, hibiscus, impatiens
Bulbs such as cannas, callas, dahlias, elephant ears
Some culinary plants can be dug up and kept on indoors
Plants that grow from cuttings: geranium, begonia, basil, mint
Growing Plants on Indoors (Warm and bright plants i.e. mandevilla, coleus, oleander)
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Bring in before frost!
Cut back to half or more /trim if needed
Use whole plant or trimmings for cuttings (begonia, geranium, coleus, hibiscus, impatiens); sometimes
fewer pest problems with cuttings/smaller plant size
Get plant acclimated by bringing it in stages; move it to shade outdoors; bring indoors during night
Inspect for bugs on plant and in soil; treat for bugs with a soap spray or by immersing in water
Place in a sunny (east, south, west) location to keep it growing on; give them a ¼ turn per week
o Find the right place for the right plant; some prefer cool/dark, some a cool/light location; house
windows vary widely depending on orientation, trees, overhangs etc
Inspect weekly for pests; treat as needed; sticky strips, soap sprays etc
Trim and remove dead leaves as needed
Water when dry; daily spray increases humidity and reduces pests
When the days start to get longer, and there is new growth, increase water and then start to fertilize
Repot (if needed) one pot size up; use a commercial mix or potting medium of good compost/organic
matter and builder’s sand (for drainage); mandevilla likes sandy well drained soil
Move outside gradually; first in shade, then sunnier location; plant out when all danger of frost has
passed; after the May 24th weekend
Other plant suggestions:
o Rosemary: under lights; water once a week
o Herbs will grow in a bright window
o Passionflower, Begonia, Coleus, Elephant’s ear (colocasia, alocasia), Hibiscus, Banana plants
o Clivia: cool and bright conditions
Keeping Plants Dormant (Cool and dark plants i.e. Agapanthus, Angel’s Trumpet (Brugmansia), Duranta,
Pineapple lily)
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Banana plants (cut back to stump; wrap root ball in plastic bag to keep moist; top of plant exposed)
Elephant’s ear (colocasia, alocasia) (cut back just above soil level and shake off soil ; keep moist, not wet
in plastic bag/pot)
Forcing dormancy is useful if you're short on space for houseplants or want to save time and effort on
winter care.
Start to decrease watering before bringing in.
Put the plant, either potted or with newspaper wrapped around its root ball, in a cool (not below 40°F),
preferably dark place for winter.
Allow the soil to dry somewhat but not completely
Check every few weeks and water/mist sparingly if needed.
Discard any dead leaves, diseased, rotting parts.
In spring, replant outside after danger of frost is past or place in a warm, well-lit place and resume
watering.
Bulbs (cannas, dahlias, Caladium spp. and tuberous begonias)
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Wait until after first frost; cut back the foliage to about 3 or 4 inches; leave the bulb in the ground for
eyes to develop
Use a fork to dig up to avoid cutting bulbs; cut bulbs are subject to disease; brush off the soil and lay
them out in a dry, airy, warm place for two weeks. (Dahlias-you can wash off the soil.)
Divide if necessary; one eye per tuber; some recommend dividing in the spring.
Overwinter in dark, cool (10 C), dry, yet airy surroundings, usually a basement. Medium: newspaper,
vermiculite, wood shavings. Containers: empty pots, shallow crates, boxes.
The storage container depends on the type of bulb, corm or tuber.
o Gladioli and bulbs with a papery husk: place in mesh bags with plenty of air circulation. Don’t
water; check once a month and discard any that show signs of rot.
o Dahlias, cannas, caladiums, tuberous begonias: store uncovered in trays or boxes loosely
packed with vermiculite, dry peat moss, wood shavings. Check every month to see that they
aren’t drying out; mist or sprinkle a few drops of water over the vermiculite or peat moss to
keep it plump; don’t overdo the water or rot may set in.
If plants start to sprout in early spring, pot them up and grow them in a sunny window or a cold frame if
you have one. Large plastic bottles over plants can also protect plants.
Challenges
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Light: Supplement with grow lights, LEDs, reflective material (white cardboard); artificial lights-aim for
12-16 hours on per day
Humidity: place on bricks on water filled trays/saucers ; spray weekly or daily
Pests: inspect weekly; spray as needed (follow instructions for using insecticidal soap-need to spray 3
times over 10 days and rinse after spraying)
o Mealy bugs; little fluffy tufts; wash foliage regularly; dab fluff with Q-tip dipped in alcohol
o Scale: roundish, flat bumps on plants; insects hiding under “bump”; difficult to remove and
treat; rub/scrape off or hand pick; prune large infestations; dab with Q-tip dipped in alcohol;
insecticidal soap will work on larva, but not adult scale; horticultural oil will control all stages
o Aphids, white fly: wash/spray foliage regularly; insecticidal soap; use “yellow sticky” tape
o Spider mites; tiny sucking insects on underside of leaves; thrive in dry conditions; make sure you
are watering properly; increase humidity around plants and spray/mist leaves; prune heavily
infested areas; spray with insecticidal soap
Soil: use a good quality potting soil; water only when dry
Limit the shock: don’t dig up, spray, repot, cut back, move all in one day! Cut back once it is in the house
and looks healthy
Leaf drop is normal for some plants due to the shock of living indoors etc; they could still perk up; don’t
water much if no leaves; new leaves produced will be better adjusted to indoor light
Decline: some plants may only just survive the winter indoors, but once put outdoors again, they
brighten up!
Have fun; the worst that could happen is that the plant could die; and that would happen if you did
nothing anyways!
Herbs
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Bring in any container herbs, like basil, parsley or sage to keep them in active growth in a bright,
south-facing window over the winter.
Keep the soil just moist.
They’ll continue to grow, but at a slower rate than in the summer due to winter’s lower light levels.
Drying parsley in the microwave (or basil)
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Place a layer of parsley heads on a sheet of paper towel.
Cover with a second sheet
Microwave for 2 minutes
Open microwave door for 2 minutes
Repeat once
Check how dry (crispy) the parsley is and repeat once if needed.
Crumble and put into air tight jar.
Stays green all year.
Drying Globe Onions
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When neck “flops” over; harvest during dry weather
Pull and lay out in sun on soil (if dry) or in a garage/shed on paper
Don’t bump or bruise
Mild onions should be used within a few weeks; pungent onions should be cured for 2-4 weeks in a
warm, dry and breezy location; one layer only
When the necks are completely dry, bring the onions indoors and store them in mesh bags, a bushel
basket, or a flat cardboard box with some holes punched in it.
Use any that have green necks or are bruised or damaged
Keep the onions as cool as possible (35 to 40 degrees F.) and away from light.
A good storage onion kept in a cold, dark place will retain its eating quality for 10 to 12 months.
Mild onions (Spanish onions, Bermuda onions and Vidalia)
o Typically large and juicy with thick rings and thin, papery skins that peel easily
o Cooked (onion rings) or eaten raw
o Poor keepers
Pungent onions (Candy, Copra, Red Weathersfield and Ebenezer)
o Usually smaller in size, thinner rings, tighter skin
o Make your eyes water when you cut
o Sulfurous compounds that draw tears inhibit rot, so more pungent onion, the longer it will store
Tomatoes
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Freezing
 Clean, remove top core and any blemishes; Cut tomatoes in quarters; bag and freeze
 Defrost to use in soups and sauces; skins will come off easily if you do not wish to include them in
the soup
Ripening green tomatoes
 Wrap green tomatoes in newspaper; store in shallow boxes in a cool, dark space; use as needed;
Figs (trench or…)
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1. Figs grow best in 15-gallon containers filled with a 2-to-1 mix of soilless mix and compost that's been
amended with a granular organic fertilizer. Make life easy and place the container on a rolling caddy.
Plant a small, hardy variety, such as 'Alma', 'Celeste', or 'Brown Turkey'.
2. Allow the tree to go dormant before you bring it in for the winter. Taper off watering the week before
your first expected frost and expose the tree to a few light frosts. This encourages sap to move down the
stems and leaves to drop.
3. Remove any remaining leaves and fruit and inspect the plant and potting soil for insects. Spray the
plant with dormant oil to kill off any lingering pests or eggs, and move it to a dark, dry location that stays
just above freezing, such as an unheated shed or garage. If your overwintering site is light, wrap the
plant in dark fabric to prevent it from breaking dormancy early.
4. Keep the soil almost completely dry during the winter, because moist soil can rot the roots.
5. Move the plant back outside two weeks before your last frost. Place it in a warm, sheltered area (for
example, against a brick wall), water it thoroughly, and apply a granulated organic fertilizer to the soil. If
frost threatens, either roll the plant inside for the night or wrap it in a heavyweight row cover. The fig
should begin to leaf out and grow actively within a few weeks.