IN THE GARDEN

By Doreen Trudel

Here we are in October already and once again it is time to rake leaves, tidy the garden and give new trees and shrubs a jump start by planting them in fall. It is also a great time to re-plant containers for winter interest. A few pots by the front door or on the deck are nature’s jewelry during the holiday season. They can brighten a dull corner and enliven a barren vista.

When choosing an outdoor container make sure that it is frost proof. Many of the ceramic or terracotta planters will crack, peel or break if left outdoors. Even keeping them dry and under cover are not a guarantee they will survive the cold. The new resin pots can withstand a freeze and they come in a variety of sizes and prices. Now is the time to look for end-of-season bargains at the larger garden centers.

Half-barrels or very large containers are ideal. They allow you to rotate displays of larger more dramatic shrubs, leaving them for a few years before transplanting the plants into the ground and designing a new arrangement for the barrel. The pot becomes a sort of plant nursery and lets you highlight a favorite or unique specimen. Conifers, small trees or Hydrangeas are a few plants that respond well to this plan but most shrubs and trees would transplant successfully from a pot as long as they do not become root-bound because you would be able to move the plant with most of its root system intact.

Rather than using garden soil in your containers use a commercial potting mix because it is lighter weight, well-drained yet retains moisture and is disease free. They are sterile so even though it is winter and we usually do not want new growth at this time of year I add a small amount of organic fertilizer which has low nitrogen content to encourage root growth rather than leaves. Remember to always keep about an inch of space above the top of the planting medium and the rim of the pot so you won’t lose any soil when you water. If your container is under eaves or under a heavy tree canopy it may have to be watered even in winter.

hen designing for a winter container remember the idea of nature’s jewelry, think bold, eye-catching, dramatic. Unless the planter is right by the front door you will probably most often see it from a distance so make the plants taller or larger than their immediate surroundings. Rather than using several smaller pots use a single larger pot or a cluster of two or three pots at the most. Arrange them in unusual places in your landscape.

If they are inappropriate for your spring and summer garden simply move them next season but for the next few months it might make you smile to see a beautifully shaped yew tree in the middle of your perennial bed or since we do not have to mow the grass why not decorate your lawn with some interesting potted shrubs. If you buy or make plant stands with small feet so that air can circulate beneath the pot, you will not kill your grass.

No matter how large or small your garden is, beautiful containers let you enjoy the rewards of gardening throughout the year and once you have planted your pots here is some information to help you choose the right plants for the rest of your garden.

When reading plant catalogues this winter or visiting garden centers next spring you will usually see a zone number listed in the plant description. This number comes from a plant hardiness zone map and denotes a climate zone in which the plant is most likely to survive based on the average coldest temperature. Because we frequently read gardening books, magazines and websites from various countries and even order plants from around the world, it would be easier if the international community recognized one common hardiness map but unfortunately there are several different maps or charts depending on the country, continent or publisher.

Although this is a complicated subject I suggest you learn the zone number for your area on the maps which you are most likely to use, realizing that Point Roberts and Tsawwassen are in a micro-climate that does not exactly fit the current hardiness maps. We are combined with Vancouver which is frequently colder and wetter. The four plant hardiness designations I use are the USDA map, the Agriculture and Agri-Food Canada chart, the Sunset publishers map and the European hardiness map.

The temperature range varies slightly from map to map and some systems now take into account changing weather patterns, elevations, air flow and other factors.

According to the USDA map we are in zone 8b, sometimes noted just as zone 8, with the average annual minimum temperature of 20 to 15 degrees Fahrenheit but that low temperature happens so infrequently here I also considered us in zone 9a with a minimum temperature range of 25 to 20 degrees Fahrenheit.

Plant growers in Canada frequently use the USDA zone map because the U.S. is such a big customer but do not be surprised if you see a 6B designation in a Vancouver nursery as this is the designation for Vancouver on the Ag-Canada website.

In Sunset magazine which uses their own very detailed zone map we are placed in zone 4. Reading the climate zone chapter in a Sunset garden guide is very informative.

The final hardiness zone designation that I use is the European Hardiness Map. It only has listings for continental Europe and the British Isles because our climate is similar to southern England which is zone 8 on the European map. If we see a reference in a British publication or catalog for a plant that does well in zone 8 we know it will grow in our climate also.

Some nurseries have already begun switching to a hardiness designation that includes both a minimum and maximum temperature tolerance. This is sometimes noted by two sets of numbers. If you see a single designation of 6 - 8 you will know that the plant can tolerate a cold temperature down to zone 6 but not a high temperature greater than that in zone 8 so although that plant can handle a low of 0 degrees fahrenheit it would never survive the warm desert southwest for example.

This is a lot of information to digest but understanding zone maps is just as important as understanding soil, sun and water requirements of various plants.

Plant Suggestions for Winter Containers
The list of potential container candidates is lengthy but here are just a few you might find at your local garden center. Be creative as almost anything can be grown in a large pot for at least a few seasons.

Evergreen shrubs: Sarcococca Hookeriana, Viburnum tinus, Skimmia Japonica, Daphne Odora, Camellia, Ribes laurifolium, Coronilla valentine, Ilex (holly), Euonymus Fortunei “Silver Queen”, Nandina
Deciduous Shrubs for bark and stem interest: Rubus cockburnianus, Cornus alba, Cornus sanguinea, Corylus avellana ‘Contorta” (Harry Lauder’s Walking Stick),

Conifers: Thuja orientalis, Picea glauca, Chamaecyparis obtuse, Cedrus deodara, Taxus (yew), Calocedrus, Sciadopitys verticillata, most dwarf varieties of conifers.

Grasses: Many grasses thrive in pots just remember they may need summer watering. Miscanthus sinensis, Carex buchananii, Hakonechloa macra, Helictotrichon sempervirens (blue oat grass), Panicum virgatum, Pennisetum alopecuroides, Schizachyrium scoparium

Most spring blooming bulbs can be planted in containers.