Some simple gardening activities can help your much-loved garden plants not only survive the winter months but be well prepared for spring as well. These tips apply to the south-eastern portion of Australia in particular.
Before we get to the practical stuff, here are some facts to assist your winter gardening decision making:
- * Water has insulating properties. This is particularly relevant for soil moisture and water in plant cells
- * Mulch is also insulating
- * Cold air is usually also very dry
- * Rapid freezing and thawing of plant tissue causes damage
Watering is possibly the most effective way of reducing Winter damage to your garden plants.
Watering your garden during Winter may seem unnecessary. In some parts of Australia and during some seasons this is the case. However, when prolonged dry periods occur in winter, well-timed watering can save your garden from stress, damage and even plant loss.
Due to the insulating properties of water, well-watered soil absorbs and retains heat from solar radiation during the day which it re-radiates during the night. Put simply, moist soil will tend to stay warmer for longer than dry soil. In addition to keeping root zones warmer, this elevates air temperatures around the plants above. Temperature increases are only slight but can be sufficient to prevent plant damage. The take-home message is don’t let your garden soil dry out too much during cold periods.
Watering is best done early in the day. This maximises the period of solar radiation absorption by the moist soil, ensures plant foliage is dry before nightfall and gives the plant time to absorb the water into tissues. Rapid cooling/freezing of water on plant tissue can cause damage and is avoided by applying water to the root zone only (ie not wetting foliage). Also, plant cells plump with water will incur less damage in the cold than cells that have dried out.
Pay particular attention to soil moisture content on cold days. Cold air is usually dry – you know how dry your face and hands can get during winter. Combined with winter winds, cold air can remove water from plants faster than roots can absorb it.
When watering in winter, aim to moisten soil throughout the entire root zone. Do not over water such that the garden soil becomes soggy. Not only will this reduce the oxygen available to the plant roots, but it may also take a long time for the soil to dry out again, increasing the risk of soil fungus. Prolonged saturated soil conditions damage the root systems of most plants. Watering the first few centimetres of soil will likewise not achieve the desired effect.
With soil moisture and temperature an issue in winter, it follows that mulching has a role in preparing your garden for the colder months. The insulating properties of the mulch itself will guard against soil temperature extremes. A well-mulched garden will retain soil moisture, enhancing the effects discussed above. Both organic and gravel mulches are useful for achieving these goals.
Young plant tissue is more susceptible to damage by the cold. To avoid new growth coming into the cold months, don’t fertilize your garden with nitrogen late in the growing season.
In the event of plant tissue damage, resist the temptation to remove the damaged branches by pruning until the risk of further damage has passed. It may look a little unsightly but this damaged tissue is protecting the remainder of the plant from further damage by the cold. Also, early pruning may stimulate new shoots that will likely suffer cold injury before spring arrives.
Frost damage is greatest when rapid freezing and thawing of plant tissue occurs. In climates where frost is uncommon, the keen gardener can cover plants with old sheets, blankets and even plastic during forecast frosty nights. Be aware that some plant tissue damage can occur where the frozen cover contacts the plant but overall the plants are protected. In the morning rapid thawing can be caused by sunlight hitting a frosted plant surface. To reduce the effects of this, gently water the frosted foliage before the sun touches it.
In frosty areas, plant nurseries avoid damage to their stock by watering at night and early morning when frost is expected with misting systems. This is a specialist technique and not practical for the home gardener.
GARDENERS PLANTHUB COLD WINTER SELECTION
Our Cool Season Grasses such as Poa ‘Eskdale’ and Poa ‘Kingsdale’ will handle cold to -10 degrees and heavy frost. Both offer a fabulous winter display. Our 3 Dianella cultivars all perform well in cool climates, with Dianella ‘Lucia’ the hardiest, surviving to -7 degrees and tolerating light frost. Most of our Lomandra cultivars do well in cold climates with the following cultivars staying evergreen to -10 degrees and coping with medium level frost: ‘Lime Tuff’, ‘Tanika’, ‘longifolia’, and ‘Katrinus’. Many other Lomandra are also cold tolerant including ‘Shara’ (-5 degrees) and ‘Evergreen Baby’ (-7 degrees).