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Shrubs - Ilex verticillata or Winterberry,

Cotoneaster, Northern Lights Azaleas, Northsky blueberry
by Jerry Filipski


Gerald (Jerry) Filipski is the gardening columnist for the Edmonton Journal, a position he has enjoyed as a freelance writer for the past 12 years. Jerry also writes for Canadian Gardening, the new Alberta Gardener as well as for the lifestyle magazine of P&O ferries. Jerry also does numerous public speaking engagements including some major gardening conferences and workshops as well as question and answer sessions for Wal-Mart and Rona.

January 6, 2002

Q.- I've been admiring 2 shrubs that my neighbour has in his backyard. I've asked him and he doesn't know what they are so I'm hoping you can help. During the growing season the leaves are dark green and almost like a holly, in fact this was the only tidbit I could glean from my neighbour, that it might be some type of holly.
During the fall and winter they are covered in masses of bright red berries that stay on the branches well into the winter and after the leaves have dropped. I didn't think holly grew here. Is it possible that it is a holly?

A.- It sounds very much like Ilex verticillata or Winterberry or Michigan Holly. Hollys do grow here, in fact there are 3 varieties reliable for our climate if given some winter protection. The winterberry is a deciduous holly. Male and female shrubs need to be planted in proximity to each other in order to produce berries.
They are one of the most dazzling shots of colour in our winter landscape when fully loaded with berries and their foliage is very attractive during the spring and summer.

Q.- Last year I had a bad infestation of pear slugs on my cotoneaster hedge. Do they overwinter? If so, what can I do to prevent the problem again this year?

A.- For other gardeners who may not know, pear slugs resemble a tiny slug and are covered with a dark olive-green or yellowish slimy covering. The front end of the larva is larger than the rest of the body.
The pear slugs overwinter in cocoons 5-7 mm below the soil surface or in leaf litter beneath the host plants. They will emerge in late spring just after the host plant is in full leaf. They emerge as pear sawflies which fly to the host plant and mate. The females lay eggs singly on the leaves. The eggs hatch in 9-15 days and the pear slugs feed for 2-3 weeks after which they drop to the ground and the cycle begins anew.
Cotoneaster, hawthorn, mountain ash, cherry, plum and pear are the trees most commonly attacked. Check plants frequently in mid-June for first generation larvae and from mid-July on for second generation infestations. To control this pest try spraying the infested leaves with a soap solution or a sprayed-on contact insecticide such as pyrethrum, rotenone, permethrin or malathion. Follow manufacturer's directions carefully as always when applying insecticides.

Q.- I have 2 large blue spruce in my front yard. I just pruned off the lower branches to a height of 4 feet (120 cm) to let more light into the rest of my plants. I've cut out all the lawn that was growing under the trees and would like to plant something under the trees. What would grow under the trees?

A.- One of the nicest little shrubs you could plant in the acidic soil under the spruces would be Northern Lights Azaleas. The semi-shaded, filtered light under the trees would be ideal for the azaleas and they would love the acid conditions. Northern Lights come in a variety of colours ranging from orchid to pink to orange.
Do not plant them too far under the trees where it is too shady, try to leave them closer to the edge of the tree so they can get more light. Other plants that will grow well in fairly acidic soil (pH 5.0-5.5) include the following:

  • Violets

  • Heather

  • Bog Rosemary

  • Daphne

  • Junipers

  • Lupine

  • Zinnia

Q.- I've had a Northsky blueberry bush for the past 6 years and although it leafs out each year and appears healthy it has never bloomed. What can I do?

A.- Chances are that the soil you have the blueberry in is too alkaline. Blueberries prefer acidic soil. The ideal blueberry soil would be a well-aerated mixture of sand and peat moss. The peat moss will help achieve a pH of 4.5-5.5 which the blueberries prefer. The soil must also be well drained.
Full sun for most of the day is essential. To promote growth and fruiting as well as maintaining acidity apply a dressing each spring of ammonium sulfate at 1 oz/sq yd(35 gm/sq m), potassium sulfate at 1 oz/sq yd (35 gm/sq m), and bone meal at the rate of 3 oz/sq yd(105 gm/sq m).


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