Tender Plants for Fall & Winter
The Chilliwack area is zone six but we can certainly enjoy the splendors of plants a zone or two higher, if we’re prepared to take care of them during the cooler months of the year.
Plants that are rated higher than zone six cannot be planted outdoors and expected to survive our winters. When the cooler nights come we must either treat them as seasonal plants (and compost them at the end of the season), protect them where they are planted, move them into frost free areas, move them inside our home (or heated greenhouse) or a combination of the above. The nature of the plant, and its hardiness, dictates how it must be cared for. We’ve selected the most popular ‘tender’ garden plants for our area and provided guidelines as to how to look after them, but if your favourite plant is not on the list, be sure to give us a call!
As most of these plants are entering a semi-dormant state, feeding is not really necessary over the winter months. An occasional feed with 20-20-20 is fine, but again, not really necessary until early Spring.
Annuals
There are few annuals that are tough enough (and worth the effort!) to come through the winter if you care for them well. This includes fuchsias, lantanas and angel trumpets. When night temperatures dip to 4-5°C, bring the plants indoors, strip them of all their leaves, and keep them in a spot where they have access to some light and can be kept in a consistent temperature range of 5-10°C. Soil should be kept just slightly moist to prevent desiccation but not so damp as to cause root rot. Acclimatize them back outdoors in the spring once the threat of frost has past, and night temps are consistently about 10°C or higher. ‘Hardy’ annuals, like geraniums, can be dug up and placed in a bright window.
Colocasias
When night temperatures dip to 10°C, move colocasias it to a bright, frost-free area to overwinter at a consistent temperature range of 10°C. Soil should be kept just slightly moist to prevent desiccation but not so damp as to cause root rot. Note, if your colocasia is in the garden, carefully dig out the plant retaining a good root-ball and transplant it into a snug fitting pot (use only sterilized potting soil to fill any additional space around the root ball). Acclimatize them back outdoors in the spring once the threat of frost has past, and night temps are consistently about 10°C or higher.
Canna Lilies and Dahlias
For Cannas: When night temperatures dip to 4-5°C, cut canna stalks to about 6” from the soil level. For Dahlias: Once dahlia foliage has died down, cut the stems back to about 4” above soil level. Then for Both: With a garden fork (a D-handled if you’ve got it), carefully dig a circle about 12” from the stems. With a garden fork, carefully lift the tuber clump out of the soil. Gently brush off excess soil, then rinse to clean, keeping the outer casing on the tubers. Check for any weak or diseased portions. Dry tubers in a warm, dry place for a couple of days, then dust with Sulphur Powder to help prevent rot. Lay tubers separately in vermiculite or on newspaper in a cool, dry place over winter. Check occasionally for any spoiling. In spring, take a sharp, clean knife and divide the tubers, leaving a stem on each. They can be planted outdoors again in the spring once the threat of frost has past, and night temps are consistently about 10°C or more.
Purple Fountain Grass
When night temperatures dip to 10°C, cut down your grass to about 2” from the soil level (yes, that low!) and bring it into a bright, frost-free area to over-winter at a consistent temperature range of about 10°C. Soil should be kept just slightly moist to prevent desiccation but not so damp as to cause root rot. Set out after the threat of frost has past in the spring (usually mid to late May).
Tropical Plants (that were set out for summer)
Colourful foliage tropicals such as philodendrons, dracaenas, tender palms, red bananas and hibiscus really need to be moved to a warmer indoor location as night temperatures begin to dip below 10°C, but if they can transition indoors by late September that would be better. The goal is to transition them inside while the light quality and humidity level are still quite good and before our home heating system is fired up.
The secret is to find the coolest location in your home, preferably next to an east or north window, far away from heat vents (or close the heat vents if that is an option) and further still from a fireplace. If you can provide a situation like this, your tropical plants will survive the challenges of household conditions over the winter. If the optimum placement is not feasible, a south or west window is better than no light at all. Grow lights or fluorescent lighting can also be a great help, and leave them on for 14-16 hours per day.
Before you bring the plants inside, do a very thorough inspection for any insects or disease problems. Outside over the summer, they have potentially provided a nice home for many insects, especially for those who have taken up residence in the soil. A wipe down with a damp cloth soaked in a mild horticultural oil solution catches potential insects and their eggs before they become a problem. You could also spray with Safer’s Insecticidal Soap.
As for the soil, there aren’t many products available to control soil-borne insects. For crawling species, dust the soil with diatomaceous earth and for fungus gnats, apply about one-inch of washed sand on top of the soil as a deterrent for any adults wishing to lay eggs.
Once inside, mist the foliage of tropicals a couple of times a day to add some humidity, but make sure the leaves are dry at night to minimize any disease issues. Keep them rootbound in their same containers, and don’t feed them until late March/April when growing conditions improve. Wait until night temps are consistently 15-18°C before acclimatizing them outdoors for the summer.
Mandevillas & Dipladenias
These flowering tropical vines require warm temperatures in the range of 10-15°C to overwinter. By cutting stems back fairly hard, down to 10-12”, placing them in a bright window and keeping them on the dry side, they should overwinter well. Be sure to check the leaves thoroughly for scale because it is one of their main pests. Wait until night temps are consistently 10°C or more before acclimatizing them outdoors for the summer.
Citrus
Citrus prefer to stay above 5°C, so when night temps approach this point acclimatize them indoors (If left outside, they will tolerate a light frost but not temperatures lower than -2 to -3°C, so it is best to get them indoors by late September). They love being outside all summer, but when brought inside almost immediately the leaves begin to turn yellow and fall off. Indoors, they love it cool and humid, and our houses in winter are anything but. Keeping them beside the brightest window and in the coolest room in your home is the best solution. Mist the foliage as often as you can, and keep the soil just barely moist. A conservatory or greenhouse that does not freeze is ideal, or even a cool garage with a window for light can work. Acclimatize them back outdoors in the spring when night temperatures are consistently 10°C or higher.
Eucalyptus
One of the hardier varieties we carry is eucalyptus gunnii, which is a zone 8 plant. When we approach temperatures of –5°C the best thing to do is to move your potted eucalyptus into a cool garage with a window to overwinter. If, however, the pot was sunk into the ground on the south or west side of your home and wrapped with N-Sulate, it can potentially make it through a winter with temperatures of -8 to -10°C. Once temperatures warm above -5° they can be moved out again.
Dracaena Palms
When the nights dip down to about 0°C, dig up your dracaena and set it in a snug pot. Keep it in a bright, cool, frost-free area over winter. Soil should be kept just slightly moist to prevent desiccation but not so damp as to cause root rot. Set out after the threat of frost has past in the spring (usually mid to late May).
Green Banana ‘Musa basjoo’
In zone 6, Musa basjoo can be planted in the ground, and after a year or so of being established, if it is well mulched it can be cut down, frozen in the ground and still survive as shoots will appear in spring. The first year or two, however, they need to be protected. In early/mid November cut off the foliage at the top of the trunk. Encircle stalks with chicken wire (about 12” out from outermost stalk and tip) and fill the ‘cage’ with dried leaves or straw. Wrap the outside and top of the cage with poly and keep it dry. Wrapping the trunk with both insulating material (N’Sulate or bubble wrap) and plastic will prevent water from seeping into the stem. Unwrap your banana in the spring once the threat of frost has past, typically mid to late May.
Windmill Palms (Trachycarpus fortunei)
In a protected location, windmill palms are considered a zone 7 plant. Over time, as they become established, they will tolerate temperatures down to -10 to -12°C. In zone 6, they will need some proper winter protection to survive. They need to be located on the south or west side of your home and the pots buried in the ground, both for stability and root protection. When the night temperatures drop to -8 to -10°C, the top leaves need to be tied up loosely and covered with N-Sulate, then wrapped with plastic to pre-vent water from getting into the crown and rotting out the centre. It is also a great idea to wrap the stems as well with an insulating material. Heat tape around the roots can also be invaluable. This only needs to be done during a period of cold weather (i.e. less than -10°C), otherwise, enjoy their beauty all winter. Note: If you cannot sink the whole pot in the ground, be sure to move your palm to a sheltered area, follow the directions above, but wrap the entire pot and plant fully with N’Sulate and poly. Their root systems are very vulnerable to cold snaps so you need to keep them protected.
Tender Waterplants
In September, when it’s still warm, place floaters in glass ‘fish’ bowls and enjoy them indoors! Place tender potted plants in waterproof containers in a well lit, frost-free area. Acclimatize and set tender plants out again after the threat of frost has past, typically in May.
Tender Succulents
This includes echeveria, aeoniums, jade plants etc. In September, before frost, acclimatize your succulent container to the conditions inside your home. When inside, they need to be near a brightly lit window and additional lighting would be nice at night. If you need to dig up your succulents to bring them in, repot them into snug pots so that they are rootbound, and use a well-draining cactus soil. Keep them on the dry side and only water in the morning with room temperature water. Foliage should be dry at night. Do not feed until spring! After the last threat of frost has passed in the spring you can acclimatize and set them back outdoors.
Cold Snap Container Protection
Since you’re getting into cold weather mode, take a quick look at your patio containers. Plants in container gardens essentially ‘lose a zone’, so if we’re due for a cold snap, you may need to protect them. The first step would be to pull containers into a sheltered area, such as a garage, until the cold snap passes. If that isn’t feasible, creating a tripod form with tall bamboo poles then wrapping the whole container (plants, pot and all!) with N’Sulate fabric is a good solution. You can unwrap it all when the weather improves.
A Note on Roses: In early November, all your roses, even the hardy shrub roses, should be mulched with fir or hemlock bark mulch piled up at least 8-10” over the bud union or the root system. Tree roses are especially vulnerable because of the unprotected graft at the top of the stem. You could either place a silo of wire around the tree and over the bud union and fill the frame with bark mulch, or create a tripod of 2” X 2” poles to cover up past the top and wrap the framework with N-Sulate and bubble poly around the whole structure. Ensure roses are protected before temperatures dip to –5C (keep wind chill in mind!). Please refer to the Rose Guide for more information on roses.