What to do in the vegetable garden in December?
Leeks, Brussels sprouts, curly kale and parsnips wait in the bed. For the rest of the month, look at your climate.
In December, the vegetable garden is harvested more than it is sown. Leeks, Brussels sprouts, curly kale and parsnips wait in the bed. A frost even makes them sweeter. At Liège, it freezes on average nearly ten nights in December. At Valencia, almost never. So the moves of the month change from one region to the next.
December cold, region by region
One station per region, with the December averages. These are landmarks. Your garden may be colder than a lowland station.
| Region | Station | Average minimum | Average maximum | Rain |
|---|---|---|---|---|
| Belgium and northern France | Liège | 2.0 °C | 6.8 °C | 89 mm |
| Eastern France, Switzerland or Bavaria | Strasbourg | 0.8 °C | 5.9 °C | 45 mm |
| South-west France or the Po valley | Toulouse | 3.6 °C | 10.4 °C | 49 mm |
| South of France | Montpellier | 4.1 °C | 12.5 °C | 57 mm |
| Atlantic coast of Spain and Portugal | Valencia | 8.1 °C | 17.0 °C | 48 mm |
Sources: RMI (Liège, 1991-2020), Météo-France (1991-2020), AEMET (Valencia, 1981-2010).
At Liège, the RMI counts 9.8 frost days in December and 1.3 days when the thermometer stays below 0 °C all day. The first frost arrives on average on 14 November. AEMET counts no frost days in December at Valencia. Between the two, the same list of vegetables does not hold everywhere.
The month's harvests
Leeks
Winter leeks hold outside without protection, even in hard cold. The RHS, the British horticultural society, notes that frost can even make their taste milder. Lift only the ones you need with a fork. The others stay in place. In the catalogue, the Poireau de Liège is harvested from November to the end of April in Belgium.
Brussels sprouts
Start at the bottom of the stem. Pick the sprouts when they are the size of a walnut, firm and tightly closed. The RHS advises waiting for a spell of frost, which makes them sweeter. Remove the yellowed leaves as you go to let air through. In the catalogue, the De Rosny Brussels sprout is harvested from 1 October to 31 March in Belgium.
Curly kale
The Westlandse winter curly kale in the catalogue is harvested from 1 October to 31 March in Belgium and in the South-west.
Parsnips
The parsnip is ready when its leaves die back, in late summer or autumn. The RHS advises waiting for the first hard frost, which makes it sweeter. Its roots stay in the ground over winter. You lift them as you need them.
Chicons
The Belgian endive (chicon), or witloof, is harvested in the warm, not in the vegetable garden. You force chicory roots, sown in spring and lifted in late summer. In the catalogue, chicory is sown from 1 May to 30 June in Belgium.
These landmarks come from a La Libre report at a Belgian grower's.
Winter leaves
Winter spinach and winter lettuce can also be picked in December, when it is not freezing. The Géant d'Hiver Verdil spinach in the catalogue is harvested from 1 October to 30 April in Belgium. In the East, count from 20 September to 3 May. The 15 vegetables that hold from November to March are in Winter vegetable garden.
Useful protections
Winter vegetables hardly need any help. Winter leeks, the RHS reminds us, need no frost protection at all. Three moves are enough.
- Cabbages against pigeons. In winter, pigeons tear the leaves. The RHS advises a fine-mesh net. In a wind-exposed garden, also plant a sturdy stake next to tall Brussels sprouts.
- Parsnips and roots against frozen soil. A layer of straw on the row keeps the soil soft enough to lift.
- Bare soil against rain. An empty bed packs down under the December rain, 89 mm on average at Liège. Cover it with compost, dead leaves or straw. The RHS places the compost mulch period from late autumn to late winter. The rates are in Feeding the vegetable garden soil.
The last plantings
Garlic, until mid-December at Liège
The catalogue stops garlic planting on 30 November in Belgium and northern France. At Liège, Oli plants his garlic from October to mid-December. The right period depends mostly on the variety. It is written on the net bag. Soil that is waterlogged or frozen means waiting, whatever the date.
Rhubarb and raspberries
December suits plants that stay in place for years. The RHS plants rhubarb crowns from November to March, as soon as they arrive. In the catalogue, the raspberry is planted until 15 December in Belgium and until 8 December in the South-west.
An established rhubarb can also be forced. The RHS covers it in midwinter with a big bucket or an upturned bin. In the dark, the stalks grow and are harvested four to eight weeks later. Do not force the same plant two years in a row.
In the south of France, onions and spinach
The south of France still has sowings. In the catalogue, onion is planted and red onion sown there until 15 December. The Géant d'Hiver Verdil spinach is sown there until 31 March.
Broad beans wait for February
You sometimes read that broad beans are sown in autumn. The RHS does it in October and November, in mild regions and on well-drained soil, with a variety made for it. In the catalogue, the Fève Longue de Belgique is planted from February to April in all the regions where it has dates. In December, keep your broad bean seeds for February.
Preparing the next season
December is the gardener's quiet month. Take the chance to prepare the coming season.
- Have your soil tested. The result arrives in two to four weeks. Send the sample before early February if you want to plant in March. Sampling is explained in Feeding the vegetable garden soil.
- Draw next year's beds. Cabbages do not come back to the same place, nor do potatoes. The four-bed rotation is in Planning your 2027 vegetable garden.
- Sort your seeds. Look at the dates on the packets you have opened. The first sowings in the warm arrive in January. They are in The vegetable garden in January.
The app starts from your address and sets the month's list to the climate of your garden, not to a regional average. Start here.
FAQ
Do Brussels sprouts freeze?
They stand frost and even become sweeter after a frost, according to the RHS. Pick them from the bottom up, when they are the size of a walnut.
Can I still plant garlic in December?
Yes, in many gardens. The catalogue stops on 30 November in Belgium, but at Liège Oli plants until mid-December. Look at the period on the net bag. Also wait until the soil is neither frozen nor waterlogged.
How do you lift parsnips when the soil is frozen?
It is hard. The RHS advises lifting a few in advance in November, or covering the row with straw so the soil stays loose.
Do leeks need protecting from the cold?
No. Winter leeks stay outside without protection, even in hard cold (RHS).
Photo: Josef Schlaghecken, Wikimedia Commons, licence CC BY 4.0
Sources
- IRM, Statistiques climatiques des communes belges, Liège (1991-2020) : températures de décembre, jours de gel, précipitations, premier gel moyen
- Infoclimat, Normales climatologiques 1991-2020 de Strasbourg-Entzheim (données Météo-France)
- Infoclimat, Normales climatologiques 1991-2020 de Toulouse-Blagnac (données Météo-France)
- Infoclimat, Normales climatologiques 1991-2020 de Montpellier-Fréjorgues (données Météo-France)
- AEMET, Valeurs climatologiques normales, València, 1981-2010
- RHS (Royal Horticultural Society), Leeks: grow your own (rusticité, récolte à la fourche, goût après le gel)
- RHS, Brussels sprouts: grow your own (récolte par le bas, après les gelées, tuteur, filet contre les pigeons)
- RHS, Parsnips: grow your own (récolte après une forte gelée, sol gelé, paille)
- RHS, Rhubarb: grow your own (plantation des griffes de novembre à mars, forçage en plein hiver, 4 à 8 semaines)
- RHS, Broad beans: grow your own (semis d'automne en octobre et novembre en région douce, Aquadulce Claudia)
- Laura Centrella, Savez-vous planter des chicons ?, La Libre, 20 janvier 2018 (forçage à 12 à 18 °C, dans le noir, 3 à 4 semaines)
He gardens in Belgium and tries out in his own vegetable patch what the app recommends. His articles always start from a source you can check and a step you can take this weekend.
