frequently asked questions

Gardening and Planting

What are the best choices for planting on a slope?

If you have a slope in your yard that’s difficult to mow, you may want to consider a garden of native plants. This will also help protect the slope from erosion. Slopes, especially south-facing ones, tend to dry out quickly. Choose a variety of drought-tolerant plants. Try a mixture of spreading shrubs, ornamental grasses, perennials, and herbaceous ground covers for effective slope stabilization.

Some examples of plants to try include:

Shrubs – buffaloberry, dwarf bush honeysuckle, sea buckthorn, sumac, juniper, potentilla, silverberry, gray dogwood, snowberry, salal, red currant, Saskatoon berry, pasture rose, shrubby penstemon

Grasses – blue fescue, Canada wild rye, Indian grass, big bluestem, little bluestem, sideoats grama grass, panic grass, prairie dropseed

Perennials – gaillardia, coneflower, evening primrose, globe thistle, yucca, wild indigo, silphium, coreopsis, rattlesnake master, wild onion, prairie clover, goldenrod, aster, hoary vervain, yarrow, sea pink, tick trefoil, bergamot, black-eyed Susan, sedum

Ground covers – barren strawberry (partial shade), bunchberry (partial shade), moss phlox, bearberry, coastal strawberry, cinquefoil

For shoreline slopes (wetter areas) – willows, red osier dogwood, black twinberry, salmonberry, highbush cranberry, sweet viburnum, blue grama grass, big bluestem, broom beardgrass, rough fescue, switchgrass, tall grama grass

Your local nursery should be able to assist you with selecting regionally native plants best suited to match your climate and site conditions. For a list of native plant suppliers in your area click here. [http://www.wildaboutgardening.org/en/gab/section3/index.htm]

Are there problems with ground covers spreading to natural areas?

The aggressive behavior of some non-native plants can have significant consequences on natural areas. Negative impacts can include, but aren’t limited to, the crowding out of native plants, a disruption in insect life cycles, an increase in soil erosion, and the alteration of natural processes. To avoid these impacts, use plants that are native to your area. Some examples of native ground cover plants include wild ginger, foamflower, barren strawberry, wintergreen, or Canada mayflower. Examples of non-native invasive ground covers include English ivy, periwinkle, bugleweed, creeping bellflower, and crown vetch. Check CWF’s native plant suppliers list [http://www.wildaboutgardening.org/en/gab/section3/index.htm] for a source of native ground covers in your area.

Where can I find local native plants?

Native plants can be used to create beautiful gardens, enhance habitat for wildlife, and increase plant numbers that are becoming increasingly rare. To help get you started, CWF has created a list of native plant suppliers. http://www.wildaboutgardening.org/en/gab/section3/index.htm

Any suggestions why my cedars aren’t doing well?

For optimum growing, cedars should be planted where they’ll have sun to partial shade in a moist humid site. To keep needles from turning brown, they need to be planted where it’s sunny in the summer and shaded during winter months. To maintain healthy plants and minimize damage, use compost and mulch, and remember to water during extreme dry periods. It’s also very important to water evergreens very thoroughly in the fall. Since they keep their leaves through the winter, they are vulnerable to desiccation (becoming dry from lack of water) over that season.

We have summarized some common diseases of cedars from The Organic Gardener’s Handbook Of Natural Insect and Disease Control below.

Are the cedar leaves reddish-brown with the tips of branches dying back?

If you answered yes to this question, the Deodar weevil might have caused the damage. These beetles are reddish-brown in color with white spots on their backs. This is generally not a problem with healthy trees. To keep your trees healthy you must fertilize and water them on a regular basis. Use parasitic nematodes on the soil around the tree as a control measure.

Do the trunks or branches of the cedars have lesions and are the branch tips dying back?

This could be cankers caused by fungi. Cankers can result in stunted growth as they girdle the tree and kill branch tips. To treat this problem, remove and destroy any affected branches. If possible, remove and destroy the cankered area, as well as 2 inches of healthy bark that surrounds the area. If a cedar is heavily diseased, you likely will not be able to restore it. It should be destroyed.

Are the leaves yellow and wilted?

This could be explained by root rot, which is caused by various fungi species. Additional symptoms of root rot may be a discoloration of the stem wood or the appearance of string-like fungal structures. Effects on the tree include branch dieback, reduced growth, and, if not treated, death. For treatment, get rid of any infected trees so the fungus doesn’t spread.

Are the cedar leaves yellow and do small bumps cover the stems and leaves?

This may be scales caused by insects that feed on the undersides of leaves. This results in an unhealthy appearance, with yellowish bumps on the upper sides of leaves. In minor cases, you can use your fingernail to scrape off the scale. You should also prune away areas that are heavily infested or use a soft brush and soapy water to remove any scales that are on the stems. Before growth begins in the fall, consider applying a dormant oil spray to the branches and trunk. During the growing season, use a superior oil.

I would like information on the environmental effect of Bacillus thuringiensis (BT), which is used to control pest insects, such as caterpillars or mosquitoes. If these “pests” are removed, what happens to the birds that normally feed on them? Are they eliminated as well?

Bacillus thuringiensis (BT) is a naturally occurring bacterium that is used mostly against caterpillars.

BT affects insects only in the larval stage. The larvae ingest the toxin that then kills them. BT is short-lived and very selective. It only affects a limited group of target species and has been found to be harmless to predators of those species, such as birds. BT has not been found to affect humans or the environment (due to its short lifespan), so organic farmers favour it.

There are several drawbacks to the use of BT. The form of BT (BT kurstaki) used against caterpillars of pest species can also affect the caterpillars of beneficial species, such as butterflies, and therefore can be detrimental to non-target populations. The BT used for mosquitoes (BT israelensis) also affects the larvae of black flies and some gnats. While black flies and gnats are not exactly favoured species, they are important food sources for other wildlife. By severely diminishing populations of mosquitoes and black flies, you in turn affect other wildlife populations.

One of the primary threats from the overuse of BT is the development of resistance in the target species. The more heavily BT is used, the faster target pest species will develop resistance to it. If you diminish pest species populations, such as mosquitoes or black flies, your predator populations, such as predatory insects and certain bat or bird species, also diminish if there are no alternate prey species available. Once a pest species develops resistance and increases in number again, there may not be enough natural predators available to keep it in check.

We recommend encouraging populations of natural predators, such as insect-eating amphibians, bats or birds (i.e., the little brown bat, tree swallow, purple martin, etc.), or predatory insects to keep pest populations under control. A healthy ecosystem is the best defence. BT is best used on a limited scale.

We had to take down a large maple tree that was diseased and in danger of coming down. We would like to do something with the remaining stump. Any suggestions?

Assuming the stump is quite short, under a metre in height, it can be used as a base for a bird-bath. Just put the bath section on the stump, eliminating the need for the base. It needs to be in a fairly open spot so predators can’t leap out and catch the birds.

You can also use the stump as a base for putting up a bird feeder or nesting box. Use it as a base for a brush pile that would provide shelter for wildlife. (Criss-cross tree branches loosely over and around the stump). Or, you could plant vines around the stump and let them grow up and around it.

If there’s no other shelter in your garden, it would be good to plant some trees for the birds. Birds will feel unsafe if there’s no shelter around.

When making your decision, take a look at the whole yard and see what needs to be added. Consider the requirements (www.wildaboutgardening.org/en/get_started/section1/index.htm ) of food, water, and shelter for local wildlife. Then, examine your yard and see what it has and what is missing.

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