Many readers have been commenting on the lateness of the changing colours of the leaves. Wait no more — fall has arrived.
The temperature is dropping, the rain is back, the nights are closing in and the deciduous trees and shrubs have answered.
Their leaves are changing to those beautiful shades of red, yellow and gold and the leaves are starting to fall.
Several readers ask, why do they change colour and what types of trees and shrubs should they select?
During the warm weather of spring and summer, the plants produce an excess supply of chlorophyll that overpowers and masks the already existing carotin and xanthophylls, which produce the yellow and gold, and also masks the pigment anthocyanin produced from sugars and tannins that give us the red. So we only see the green foliage.
Now, as the temperatures drop and we have shorter days, the chlorophyll breaks down and, as the green disappears, the yellow, gold and red come to the fore. A warm, wet fall tends to produce dull colours. Further into the season, the chemical reaction cuts off food supply and the leaves fall.
A new theory suggests that the pigments act as a sunscreen to shade and protect the photosynthetic tissues from the bright light as nutrients are being withdrawn. Also, among other things, near freezing temperatures, drought and low nutrient levels all lead to increased fall pigments.
What types should be planted to provide fall colours? Trees that have a colourful foliage include ash, blue beech, mountain ash, red maples, red oak, scarlet oak, sugar maples and white oak. Typical shrubs are amur maple, arrowwood, burning bush, dwarf burning bush, Japanese maple and smoketree.
But remember, there are some trees and bushes that, by nature, have colourful foliage throughout the season, such as copper beech, crimson king maple, royalty crab apple, shubert chokeberry, and shrubs like bloodwood, Japanese maple, dart’s gold ninebark, golden mock orange, purple-leaved weigela and silverleaf dogwood.
As fall progresses, it is time to raise the cutters and make the last cuts of the year. While on the subject of raking, rake the lawn and remove the remains of grass cuttings which, if left, will form a thatch, which prevents water reaching the grass.
Where compacting has taken place, aerate the lawn using a rented mechanical aerator, which will pull out small plugs of grass from the lawn and let oxygen into the earth and help the roots and also improve drainage.
Alternatively, you can use a garden fork and make a series of small holes. Lime can be applied, or a fall fertilizer.
Scilla (Blue Squill)
These are an early flowering type of bluebell with nodding heads. They are native and originate from Europe, Asia and South Africa and there are over 90 species. They are frost hardy and do well and naturalize in this province.
An old variety that dates from 1601 is Scilla bifolia “Rosea” pink, almost white. This is probably the earliest of the Scilla family to flower. There is also Scilla sibirica (Siberian Squill) from Iran, Russia, Turkey and Ukraine, with flower height of 4-8 inches (10-15 cm) which are principally blue.
S. sibirica “Álba” is white. There are also pale blue varieties
Jobs for the week
Start clearing your beds of annuals and use on the compost heap and prepare the ground for your bulbs. The evenings are getting dark early and with the onset of wet weather, we must use fine days for the gardening jobs, before the clocks go back.
J.J. Strong is a longtime member of the Newfoundland Horticultural Society.