Winter can be a hazardous time of year for health with the ‘Flu and colds running rampant through the population, and the plant world is no different. With the excess moisture in the air and less drying out of plant surfaces, winter creates a ripe environment for the spread of fungal disease amongst plants. These can manifest themselves in brownish spots or sometimes like powdery moulds such as with Botrytis. There are a number of ways you can help your garden to stay healthy.
1. Choose species that suit the local climate and conditions.
Avoid growing plants that occur naturally in warmer or drier climates such as from WA, SA, or Qld.
2. Don’t over plant or crowd your garden
Airflow is important in preventing the development of disease. When plants are crowded in from over-planting or poor maintenance, it limits the flow of air across plant surfaces meaning they stay moist for longer which allows the growth of bacteria and fungus.
3. Chemical Sprays
When conditions are particularly bad, some plants will appreciate a little help in fighting disease. There are a number of low-toxic sprays containing Copper or Sulphur or similar which can be applied during the cooler months to help prevent fungal and bacterial diseases. As with any chemical, make sure you read the label and follow any instructions or safety directions before use.
With cold overnight temperatures we are starting to experience frosts. Frost damage occurs when water in plant tissue and causes ice crystals to freeze and rupture the cell walls or causes the cells to dehydrate and damage occurs. Rapid thawing can also increase damage. Here are some tips to avoid frost damage or minimise its impact.
1. Plant frost tolerant plants
If your property is affected by frosts, avoiding planting species from warmer climates or more protected areas.
2. Plant hardened plants
Planting more established plants with less soft, new growth will help to reduce the risk of frost damage. More mature, hardened plants also have a greater store of carbohydrates meaning they will recover better in spring.
3. Avoid planting frost tender plants in frost pockets/low lying areas
As cold air flows downwards, low-lying areas in your garden will be the coldest.
4. Avoid pruning/fertilising in late autumn
Pruning and fertilising in late autumn will encourage new growth, which will not have a chance to harden sufficiently before frosts occur.
5. Leave frost damaged leaves on plant
As tempting as it is to remove damaged foliage from plants, leaving the dead leaves on will help to protect remaining foliage and prevent more extensive damage. Wait until danger of frosts is over in spring to prune off damaged foliage.
6. Use tree guards around young plants while establishing
Plastic tree guards create a more protected environment.
A thick layer of mulch will help to insulate the ground from evaporation and heat loss. As the mulch breaks down, the composting process also releases heat.
8. Keep your soil moist, but not wet
Moist soil can hold up to 4 times more heat than dry soil. Avoid water-logging the soil, because if the water in the soil freezes, as it expands it can push plants up out of the ground.
9. Water during potential frosts.
Watering plants will help to increase their temperature and that of the air around them. As water freezes, it also releases approximately 80 calories per gram of water. Some people have sprinkler systems in place that will come on overnight when frosts are expected.