You Must Sow These in December

, written by Benedict Vanheems gb flag


The days will soon be lengthening once more, and it’s only a few short months before sowing begins in earnest – but why wait til then? There are a few treasures you can sow right now...

Cilantro Sowing Tips

Cilantro is one of my favorite herbs, but it can be prone to bolting (running to seed). Now that’s just fine if you want to harvest the seed pods to grind up into coriander powder, but if you’re after lots of lovely cuts of the aromatic leaves, it’s not so good. Cilantro usually only bolts when days are longer, which means sowings made in autumn or winter are often far more successful.

To ensure outstanding germination, you can 'prime' or pre-sprout cilantro seeds. Place the seeds on a cloth. Gather the cloth into a bundle, then secure it with a rubber band. Soak the seed-filled cloth in water overnight, then dunk them in water twice a day to keep everything moist until they germinate.

Pre-germinating cilantro seeds
Prime cilantro seeds for best germination

Once they’ve sprouted (which should be within a week), add potting mix to a seed flat or other container, then spread the sprouted seeds over the top, making sure to avoid damaging the delicate roots. Cover the sprouted seeds over and water them. Place them a greenhouse or cold frame to continue to grow.

Harvest the leaves once they reach about 6in (15cm) tall, which should take a month or so. If you’re careful not to damage the growing point in the middle there’s a good chance you’ll get a second cut a few weeks later. Bonus!

Cilantro seeds can be expensive, but you can cut your seed bill by letting your cilantro flower once you’re done harvesting, and then collect the seeds to use for future crops. That way you can keep the cycle going for no extra cost.

Shallots in a plug tray
Shallots can be planted in plug trays under cover if your soil is frozen

Planting Shallots in Winter

Shallots are another gourmet favorite. I like to think of them as posh onions dressed up in a three-piece suit! Add them to your recipes for a streak of sophistication and culinary prowess.

Shallots are mega hardy and mega satisfying to grow, and they’re a gold-plated choice for planting in winter. You could plant them directly where they are to grow if your soil is workable, but where I live I find that the repeated freeze-thaw cycle of soil in winter means they need to be regularly pushed back into place. I prefer to start them in good-sized plug trays, filled with all-purpose potting mix blended with an equal amount of sifted garden compost to save a bit of money.

Autumn-planting varieties of shallot are fine to plant in winter too. Just push the little shallot sets into the potting mix until just the very tip sticks out. Give them a good water then grow them on in a cold frame or other sheltered spot.

Shallots planted now are ready to harvest in early summer, and will store for a long time

In early spring, transplant your shallots into well-drained soil in a sunny spot, about six inches (15cm) apart in both directions. Last summer I added dry grass clippings around the plants to help lock in soil moisture, which worked really well. Those shallots (which were also planted at this time year) were ready to harvest in early summer, a few weeks ahead of my onions.

Shallots store for ages, so you can continue to enjoy them well into next winter.

Grow Bigger Onions

All those champion onions that win prizes in the ‘biggest vegetable’ shows – I’m talking football-sized whoppers! – are sown in deepest winter, with the day after Christmas Day being the traditional date preferred by many.

Supersized onions
Space onions widely for the biggest bulbs

For standard-sized onions, it’s fine to wait until later in winter before sowing. But if you’re after king-sized bulbs, perhaps to exhibit at your local garden show, now is the time! First sift some all-purpose potting mix to a nice, fine crumb, then use it to fill a plug tray. I have found onions transplant well when sown together in one pot and then separated out as young seedlings, but in the interests of growing supersized bulbs, you need to avoid any root disturbance.

Sow two seeds per plug. You can carefully pull out or cut off the smaller seedling if both germinate. To stir your onions from their seedy slumber, bring them indoors into the warm to get them started. Once they’re up they can be returned to a cold frame or greenhouse to grow on. But if you’re after really massive onions, keep the seedlings under grow lights until light levels have reliably increased later in the winter.

Transplant your seedlings into the garden in early spring, positioning them at least a foot (30cm) apart in both directions for big bulbs.

You can also grow prized onions for supersizing in containers. Pot them on in stages into progressively bigger containers until you get to a three-liter pot. Onions in containers need special attention paid to watering and feeding to encourage consistent growth.

Harvesting basil
Grow basil for a taste of summer in winter!

Basil Under Grow Lights

There are some winter treats you can grow indoors – perfect if you’ve got green thumbs but don’t have a garden! Basil is great for growing on a windowsill or under grow lights. When the weather is grim outside, the rich smell of basil transports you to those warmer days of summer.

Sift all-purpose potting mix into a pot, then scatter the seeds very thinly across the surface. There are lots of different basil varieties to explore, but I like to grow the classic Italian variety called ‘Genovese’, because it’s quick, reliable, and very versatile. The seeds of this variety are also usually very cheap, so I can make regular sowings throughout the winter for very little cost.

Basil seedlings
Starting basil under grow lights gives them a real boost when light levels are low in winter

Cover the seeds with a thin layer of potting mix, then mist-spray the surface with water to avoid unsettling the seeds.

In many areas a sunny windowsill will be fine to germinate these seeds on, but in gloomy northerly regions you can get better results by popping them under grow lights if you have them. To help the seeds germinate, cover the pot with clear plastic held in place with an rubber band. This will create a humid microclimate to get them started. Remove the cover the moment you spot seedlings poking through the soil surface.

If you’re using grow lights, keep them on for up to 14 hours a day. Turn them on when you get up in the morning, then switch them off an hour or two before bedtime. Raise the lights as the seedlings grow so that the foliage never touches them. If the seedlings start to look crowded, thin them out a bit.

Microgreens are tiny but incredibly flavorful!

Growing Microgreens for Winter Salads and Sandwiches

If you have invested in grow lights there’s little point in running it for just a few pots of basil, so what else can you grow under here at this time of year? Pretty much anything compact and leafy! But one group of gourmet greens I love is microgreens. (You don’t have to use grow lights for these, but they will grow faster with them.)

Microgreens are simply the seedlings of larger crop plants. Harvested at a very young stage they offer little explosions of flavor which will certainly turn heads at the dinner table!

My three favorite easy-to-grow, tasty microgreens are sunflowers, peas, and mustard. To save money you can buy mustard seeds in generous bags for Indian cooking, while sunflower seeds are sold in bulk as bird seed.

Pea shoots
Use up leftover pea seed to grow a bonus crop of pea shoots

Soak peas and sunflower seeds overnight to give them a bit of a jump start. Sow them into seed flats or other shallow containers with drainage holes added. I like to use potting mix, opened up by blending in a little coconut fiber, but just plain potting mix is fine.

Drain the seeds then spread them quite thickly – but not touching – on the surface of the potting mix. Press the seeds down so they’re in good contact with the potting mix, then wet the surface with a spray mister. Place them under your grow lights where that extra light will really help to create strong, stocky seedlings – microgreens bursting with flavor! If you don’t have grow lights, a sunny windowsill will work too. They’ll be ready to cut within a week or two.

I hope you’re as excited as I am to be sowing seeds at this time of year. Satisfy that seed-starting itch this winter – keep on growing – and you’ll reap rewards that most gardeners miss!

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