What to sow in December in the UK
December is the shortest list of the year, which is a relief. The RHS suggests planting shallots and garlic in mild areas with well-drained soil, and BBC Gardeners’ World adds broad beans, onion seed (traditionally on Boxing Day), winter salads under cover and bare-root fruit. Meanwhile there’s plenty to harvest for Christmas dinner.
Sowing dates are typical UK guidance, not promises. Your soil, your region and this year’s weather matter more than the calendar, so check your seed packet too.
Plant out
Garlic and shallots
The RHS December list is short and to the point: plant shallots and garlic in mild areas with well-drained soil (RHS: December jobs). Garlic needs a cold spell to form good bulbs, which is why it goes in during autumn and early winter (RHS: garlic). If your soil is heavy or wet, Gardeners’ World suggests starting garlic in multi-celled trays, one clove per cell, kept in a greenhouse until spring and then planted out 10 to 15cm apart (Gardeners’ World: what to plant in December). The RHS also says some shallot varieties can be planted in autumn or winter, but to avoid autumn and winter planting in heavy clay soil (RHS: shallots).
Bare-root fruit and rhubarb
The RHS says to plant new fruit trees and bushes, but not if the ground is waterlogged or frozen (RHS). Gardeners’ World says bare-root rhubarb crowns can go in between November and March, with the tip of the crown just above the soil surface, and that gooseberries, raspberries and blackberries can all be planted bare-root between October and March (Gardeners’ World).
Sow outdoors
Broad beans
Gardeners’ World suggests sowing broad beans in December for a crop as early as May: direct outdoors if conditions are mild, or in cold areas into pre-warmed soil under cloches or fleece, or in trays in a greenhouse or on a windowsill to plant out later (Gardeners’ World). The RHS is more cautious, saying earlier sowings outdoors (October and November, or February) suit milder parts of the UK and very sheltered, well-drained sites, using a hardy variety (RHS: broad beans). If your plot is cold and claggy, pots are the safer bet.
Sow indoors or under cover
Onion seed
Gardeners’ World says Boxing Day is the traditional day to sow onion seed, in pots indoors or under cover, planting the young onions out in spring 10cm apart (Gardeners’ World). The RHS says onions can be sown indoors from mid-winter to early spring, in modules in a heated propagator or on a warm, sunny windowsill (RHS: onions). A family tradition with soil in it, and a reason to leave the room after the second helping of trifle.
Winter salads
- Winter lettuce such as ‘Winter Gem’, in pots in an unheated greenhouse or cold frame.
- Lamb’s lettuce (corn salad), sown in an unheated greenhouse.
- Mizuna, in the greenhouse or on a windowsill.
- Microgreens, sown and grown indoors.
All from Gardeners’ World’s December list (Gardeners’ World). Low light is the limit here, so a bright windowsill matters more than heat.
When the ground says no
A recurring theme in December advice is the condition of the soil. The RHS says not to plant fruit trees and bushes if the ground is waterlogged or frozen, and its garlic guide says wet soil makes garlic more prone to disease, particularly when planted in autumn, which is why it suggests modules for heavy, wet soils (RHS; RHS: garlic). If your plot is a puddle, the jobs move indoors: sow onions and salads, clean pots and canes, and wait for a dry, frost-free day. Bare-root plants that arrive in a cold snap can be potted up temporarily until conditions improve, as Gardeners’ World suggests for trees and shrubs (Gardeners’ World).
Ready to harvest in December
The RHS lists these vegetables as ready to harvest in December: beetroot, turnips, parsnips, Brussels sprouts, celery, swedes, cabbages and leeks (RHS: December). Sprouts taste sweeter after a frost, says the RHS, and parsnips can stay in the ground until you need them, though they’re hard to lift from frozen soil (RHS: Brussels sprouts; RHS: parsnips). In other words, if it’s on the Christmas plate, it might be on your plot.
Other December jobs
- If hard frosts are forecast, cover trenches of stored root crops with cardboard so you can still get at them.
- Stake or earth up leggy sprout stalks against wind rock.
- Add homemade compost to empty areas of the plot.
- Pick yellowing leaves off brassicas, and protect them from pigeons with cloches, netting or fleece.
- Prune apples, pears, quinces and medlars. The RHS says to avoid pruning stone fruit in winter.
- Clean and store canes; shorten broken ones for reuse.
All from the RHS December page (RHS: December jobs). There’s more in our guide to allotment jobs in winter.
Plan next year while it’s dark
December is a good month for planning. Fork Handles shows what to sow indoors, sow outdoors, plant out and harvest each month for 66 UK crops, and keeps a log of what went in which bed, with reminders before each crop should be ready. I made it for my own plot. It’s free on the App Store, with one optional one-off purchase.
Read next
Questions
Can I plant garlic in December?
Yes, in mild areas with well-drained soil, says the RHS. On heavy or wet soil, start cloves in modules in a greenhouse or cold frame and plant them out in spring.
Can I sow broad beans in December?
Gardeners’ World says yes, direct outdoors if it’s mild, or under cloches or in trays elsewhere. The RHS says early outdoor sowings suit milder, sheltered, well-drained sites and hardy varieties.
When should I sow onion seed?
Gardeners’ World says Boxing Day is the traditional day. The RHS says onion seed can be sown indoors from mid-winter to early spring, in modules in a heated propagator or on a warm windowsill.
What vegetables are ready to harvest in December?
The RHS lists beetroot, turnips, parsnips, Brussels sprouts, celery, swedes, cabbages and leeks as ready to harvest in December.