Do I need frost protection?
- Depressions (lower areas) in a garden or landscape will be colder and more prone to frost. Cold air is denser and will settle in the lower areas. These areas will need direct sunlight to heat up quicker in winter.
- Soil type: Different types of soil will store and conduct heat differently. You can therefore suffer more damage when the soil cannot hold heat. Heat transfer from highest to lowest: Sand>Clay>Peat. In other words, organic soils we often use for gardening does not transfer heat well.
- Place sensitive plants away from windows and windowsills. The air closest to the glass will be the coldest.
- The position of a tree or shrub will influence airflow and in turn heat transfer and radiation. Professionals often use smoke to study the flow of air in a landscape on frosty nights. This allows them to disrupt or divert the flow to avoid severe frost damage.
- Some may opt to level out depressions, while others select more frost hardy plants for the lower-lying areas.
- Choosing trees and shrubs with a delayed flowering time will avoid bud drop at the start of spring (or when there is a “false spring” followed by cold weather).
- Canopy trees can “hold onto heat” or, more accurately, create downward radiation. An example is the use of shade trees in Brazil to protect coffee plantations.
- Grouping plants can raise local heat radiation and minimise frost damage.
- Frost damage is more prevalent in unhealthy trees that have not received adequate fertiliser. They lose leaves quicker and bloom too early. Fertilising with the correct fertiliser makes the plants more robust.
- Pests damage the protective layer that plants rely on during cold spells. Damaged bark or leaves will therefore die off quicker. Make sure to check plants regularly during late summer and autumn.
- Pruning is subject to different plants, but it is good to prune grapevines later and citrus well before the first frost. In this case, it is good to keep in mind that pruning causes an open wound that should heal in time for the first frost.
- Soil tilling or disruption creates air pockets that are poor heat conductors. This will add an additional chill factor.
- Watering should be avoided in the days leading up to a cold spell. Rather water a few days ahead, allowing the sun to dry the topsoil but still contain some moisture.
Active frost protection
- Frost protection fabric: This is woven polypropylene fabric rolls, not to be confused with shade protection (see article on Shade & Greenhouses). They are normally labelled as 17 or 30g per square metre. The heavier fabric provides more protection (layering the fabric will increase frost protection). Note that each layer will block out more sunlight.
- Plastic covering: Plastic is non-breathable, providing a way to capture and hold solar radiation. As moisture evaporates, it condenses into droplets on the plastic that should not touch plants (if the plastic touches the plant it will still suffer frost damage).
- Cold frames: Cold frames work in a similar way to plastic covering, keeping the solar heat inside. It is best to build cold frames to face south, taking care that it does not fall in any shade during the day.
- Extra insulation: A cold frame can be covered with additional fabric or bubble wrap to hold onto extra heat, but at the loss of filtered light.
- Heating coils/mats: Commercial heating mats or coils are available for use indoors. These can be a great resource if treated with care (either put on a timer or alarm). Electrical appliances should be inspected regularly for potential wear and tear. Even if the appliance is waterproof, one should take precautionary measures to expose them to as little water as possible.
Newly planted veg bed - cobbled together in the new garden with bits and pieces left behind by previous owners. All done since lockdown started. Broad bean and beetroot plants with more broad bean seeds down the middle. Frost protection also cobbled together.
Greenhouse full of cuttings and plants saved from last summer. I need to get the bubble wrap down and start hardening off, ready to go in pots next month. Never enough space.
Thanks to advice from Candide contributors I have bubble wrap per the greenhouse ready for winter, to protect salvia cuttings, sweet peas, lettuce and spinach, with the minimum of heating I hope
Homemade cold frame #beginner #lockdown
⚠️Cold Frame Update⚠️