Gardening

with Deryn Thorpe

Planting deciduous trees in winter

Ask your nursery about bare-rooted products

bare rooted

After attending a talk recently on bare rooted deciduous trees, I'm totally convinced that these are the best and most economical way for gardeners to add new trees during winter.

The trees are grown in the field and at about two years old are dug up when they're dormant, have all the soil washed from the roots and are shipped to retail nurseries ready for planting.

Since the trees are less costly to transport, and do not have the added expense of a pot, they are between 20% to 50% cheaper than similar container specimens.

You'll only find them for sale over the next month or so because in August they start to shoot which means that they cannot be transplanted.

Most deciduous plants come from regions which are very cold and they shed their leaves and stop sap flow for the duration of the cold period.

While they do look like they are completely dormant there is biochemical activity going on inside including the production of growth hormones, called gibberellins, that initiate flower and bud formation.

The colder the weather the more gibberellins are produced which means that trees in regions with long cold winters have a high chilling requirement to stop them bursting into bud while the weather is frosty.

This reaction to the cold means it is essential to buy fruit trees suitable for your climate. Deciduous fruit trees are usually labelled as needing a low, medium or high chill factor. This requirement varies between varieties within a kind of fruit. The chilling requirement for a variety is defined as the accumulation of hours below 7C.

Satisfying the chilling requirement will result in normal growth and bloom and usually garden centres in your area will only sell trees suitable for your conditions but it pays to check. In general, the higher the chilling requirement of a variety, the later the bloom will occur in the spring.

Gardeners in Perth, Sydney, sub-tropical Queensland and other warm areas should look for deciduous fruits with a low chill factor as these need 600 chill hours or less and are the only ones that will reliably set fruit in their warm climate.

High chill varieties can be grown in cold climate areas such as Tasmania and Victoria.

When you buy a bare rooted tree you should prune it before planting it in your garden as the roots mass is reduced when the plant is dug up. It is important that the branches are reduced to match the smaller roots.

Once you buy the tree you should keep it moist so try to plant it out as soon as you get home. Dig a hole, improving the soil with clay if you have sand and add compost to all soils. Water it in well and water deeply during the drier months for the first two years.

Plant the tree at the same level as when it was in the ground. If you look closely at the bottom of the stem you can see a change in colour which indicates what part of the stem was below ground.

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