Frost Protection and Migitation
Frost can cause serious damage to your plants; injuries are irreversible and there is no other means of treatment apart from trimming out or pruning the affected parts. The symptoms of frost damage include (i) soft, young or succulent tissue bears a water-soaked appearance when thawing, (ii) wilted and browning and subsequently blackened on the leaf tips of evergreen plants.
WAYS TO MITIGATE FROST INJURY
1. Know your plant, know your garden
Check on the plant’s hardiness. The information of plant hardiness is easily available on the internet. It can be compared to the UK hardiness index and hardiness zones. The UK hardiness index ranged from H1a (tender) to H7 (hardy). This will provide insight on which plants are suitable for certain zones, and which plants will need more attention during winter. Avoid planting tender plants at dips or slopes area as this area may be a “frost pocket”.
2. To cut or not to cut
At the end of the flowering season, cutting back or dead heading is done to promote new growth. However, dead heading is not suitable for all plants, therefore it is worth investigating before doing so. For example, although they have wilted, do not cut back Brunnera as the leaves are able to protect the crown during winter.
3. Root health
The roots are the most important organs that requires protection from frost. The smaller roots and root hairs are easily damaged by freezing and thawing water in the soil. Container grown plants can be protected with coir mat or padding. You can also apply mulches, straws, used gunny sacks or soil insulation.
4. It’s a wrap
Wrap tender plants with garden fleece.
5. Store them away
It is best to bring indoors or transfer tender plants in containers into the glasshouse. Underground stems such as rhizomes, tubers and corms (e.g. Dahlia, cannas) can be lifted, stored in containers and kept indoors in the dark.
DO NOT feed plants with high nitrogen fertilizers during winter as it will cause the plants to go sappy. However, DO feed them with Potassium and/or Magnesium rich fertilisers. These nutrients accelerate photosynthesis and build up food storage which makes the plants less susceptible to injury and regulates water movement. Adding Calcium as a micronutrient will strengthen plant cell walls and help them avoid weakening during freezing and thawing.