Our 10 tips for frost in the garden
When to start, which plants are most vulnerable and how to protect them. Plus what frost does to wooden garden furniture. Frost strikes unexpectedly and in a single night does damage that costs you a whole season. With a little preparation, your garden comes through unscathed.
Tips & maintenance · Season
SeasonTen tips against frost
Frost strikes unexpectedly and in a single night does damage that costs you a whole season. With a little preparation, your garden comes through unscathed.
- From 5 °C at night
- Moist soil freezes more slowly
- Protection off only after mid-April
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When do you start?
As soon as night temperatures drop below five degrees on a regular basis — in our climate usually from October.
Waiting until it really freezes is too late, because the damage happens on the first night. Follow the forecast and act ahead: an early frosty night in September can already hit Mediterranean plants while the rest of the garden is still in full bloom.
What you protect depends on what you have. Citrus trees, oleanders and geraniums are distinctly frost-sensitive. On top of that, all young plants that are not yet well rooted are vulnerable, as is everything you planted only this year — their first winter is always the hardest.
And one counter-intuitive rule: water before the frost sets in. Moist soil conducts heat better than dry soil and so freezes more slowly. Do it in the morning, on the root zone, and not in the evening just before a frosty night.
Solid wood can withstand frost; you do not need to do anything for that. What you do need to do: bring the cushions inside, and make sure water cannot sit anywhere where it will freeze and expand — in a parasol base, in an empty planter or in a clogged joint.
- Start
- when nights regularly drop below 5 °C
- Mulch layer
- 5 to 10 cm around the base of the plant
- Watering
- in the morning, on the root zone
- Pots
- lift off the ground onto wooden blocks
- Most vulnerable
- Mediterranean plants and everything planted this year
- Removing protection
- in our region usually after mid-April
- Snow
- a thin layer insulates, a heavy one breaks branches
To be fair: frost protection that you leave on is worse than no protection. Fleece and plastic still around the plants in March hold in moisture and cause mould — just when the plant wants to grow again. Put in your diary when it needs to come off, because that is the step everyone forgets.
In pictures · Ten ways to prevent frost damage
Schematic drawing.
Ten ways to prevent frost damage
1. The right materials
Fleece, jute or plant covers hold in warmth without sealing off the air completely. Choose light-coloured material, so it does not overheat on a sunny winter's day.
2. A mulch layer
Five to ten centimetres of straw, leaves or compost around the base of the plant keeps the soil temperature stable. It also improves the soil structure as it breaks down.
3. Moving pot plants
To a sheltered corner, an unheated conservatory or the garage. Lift pots off the ground onto wooden blocks, so the roots do not freeze through the cold surface below.
4. Wrapping young trees
Jute or a tree guard around the trunk prevents frost cracks, which are caused by rapid temperature swings between day and night. Let air in to avoid mould.
5. Watering before the frost
Moist soil freezes more slowly than dry soil. Water in the morning, aimed at the root zone, and not in the evening just before a cold night.
6. Make use of microclimates
Walls, fences and buildings store heat during the day and release it at night. Deliberately put your most sensitive plants in those warmer spots.
7. Windbreaks
Icy wind lowers the felt temperature and dries plants out. Bamboo mats, an evergreen hedge or wattle screens break the wind.
8. Covering winter vegetables
Cabbage, spinach and lamb's lettuce tolerate light frost. In hard frost, cover them with fleece — and open it again during the day so light and air can get in.
9. Leaving the leaves
Fallen leaves in the borders are free insulation and mimic what happens in a forest. Surplus leaves go on the compost heap.
10. A frost action plan
Make a short list in advance of what needs protection first, and have fleece and jute ready. That way you do not have to go searching when a frosty night is forecast.
What frost does to wooden furniture
Wood itself has little to fear from frost. What causes damage is water that creeps into a crack or a joint, freezes and expands — prising the fibres further apart. So every winter makes an existing crack a little bigger.
Cushions inside
Even water-repellent cushions collect dirt and moisture if they spend the winter outside. In a cushion box they last years longer.
Get rid of water
Empty parasol bases, turn empty planters upside down and clear clogged joints between deck boards. Water that sits and freezes does the most harm.
Cover with care
A breathable cover helps; a plastic sheet traps moisture and speeds up exactly what you want to avoid.
Off the ground
Stand furniture on tiles or on feet, so the legs are not in a puddle or in frozen soil.
Sweep away leaves
A layer of wet leaves on a tabletop or deck holds moisture against the wood for months.
No sanding in frost
Do not treat or sand outdoor wood in winter. Every coat needs warmth and dryness to bond — that comes in spring.
Frequently asked questions about frost protection
When should I start protecting against frost?
As soon as night temperatures regularly drop below five degrees, usually from October. An early frosty night in September can already hit Mediterranean plants.
Which plants are most sensitive?
Mediterranean and subtropical species such as citrus, oleander and geranium. And everything newly planted and not yet well rooted — the first winter is always the hardest.
Can I overwinter pot plants in the garage?
Yes, an unheated but frost-free garage is fine. Give them as much light as possible, water sparingly and check every two weeks for drying out and mould.
Should I remove snow from my plants?
A thin layer acts as insulation and does no harm. Heavy snow on branches can cause breakage, especially on conifers — shake it off gently with a soft broom, from the bottom up.
When do I take the protection off?
Only when the risk of night frost has truly passed, in our climate usually after mid-April. Do it gradually: first air the plants during the day, then remove it completely.
Does my wooden garden furniture need to come inside?
Wood can withstand frost. But make sure water cannot sit anywhere where it will freeze and expand, and bring the cushions inside.
The rest of the year
Every season asks something different of your garden and your furniture.
Have a question about your project? Just ask — we're happy to help.
Photos via Wikimedia Commons: Kohlrabi under white horticultural fleece (Brassica oleracea var. gongylodes) — Josef Schlaghecken, CC BY-SA 4.0 · Thick layer of wood-chip mulch around the base of a shrub — Raffi Kojian, CC BY-SA 3.0