"March is the month of expectation."

Seeds to Sow in March: Setting things in motion

At this time of year, patience really is our best gardening tool. Sowing seeds into cold ground can result in slow, patchy germination or no germination at all. In many cases, waiting a short while for conditions to improve will lead to healthier, stronger plants. While it’s exciting to get started, sowing too early can lead to disappointing results, as cold soil makes it harder for seeds to germinate well. Waiting just a little longer can often make all the difference.

Preparing Beds in March

Preparing the ground now helps towards success later. I break up the larger lumps, raking the soil to create a finer surface ready for sowing. Covering the bed with polythene can also be useful at this stage. Clear polythene lets light through, encouraging weed seeds to sprout so I can lightly hoe them off before planting. Black polythene blocks out the light, helping to reduce early weed growth, though dormant seeds may still appear once the cover is removed.

Let the Soil Lead the Way

Each vegetable has its own comfort level when it comes to soil temperature. Some hardy crops are happy to get going once the soil reaches around 5°C, while others need warmer conditions before they’ll sprout. Rather than relying on the calendar, try sticking your thumb in the ground. If it feels cold to you, it will feel cold to the seeds too.

Taking your cue from the soil helps avoid disappointment and gives your crops a much better start.

Some hardy vegetables can be sown outdoors if the soil isn’t too cold or wet, while others are best started under cover for a more reliable start.

Direct Sow

Broad beans; one of the hardiest crops; good for early sowing in well-drained soil

Peas; early varieties can be sown now, in milder areas or under fleece

Spinach; tolerates cooler soil and grows quickly once temperatures rise

Beetroot; sow towards the end of March as the soil warms

Carrots; sow early varieties in containers or into light, stone-free soil

Parsnips; benefit from early sowing as they take a long time to germinate

Radishes; quick to grow and useful for marking slower rows

 

Hardy annuals such as clarkia, sunflowers, Brompton stocks, poppies, and cornflowers can be sown direct as the soil warms.  in a sunny position direct sow wildflower seed mixtures into raked soil (see preparing the ground above)

 

Sowing Under Cover as a Backup  

For a little extra reassurance, it’s a good idea to make some sowings in module trays indoors. These seeds grow on in warmer, more reliable conditions, producing sturdy young plants ready to go out when conditions improve. I find they’re also invaluable for filling any gaps where outdoor sowings fail.

Under cover (greenhouse, cold frame or indoors) sow:

Lettuce; reliable under cover and easy to transplant later

Cabbage; spring and summer varieties do well from early sowings

Cauliflower; start under cover for stronger plants

Brussels sprouts; early sowing for a longer growing season

Kale; hardy but benefits from a warm start

Leeks; early sowing produces sturdy plants for transplanting

 

Also, sow Sweet Peas in root trainers and tender climbers like Cobaea (Cathedral Bells) or Thunbergia (Black-eyed Susan).

In the Propagator

March is the ideal time in the UK to use a propagator for heat-loving crops and early starters if you have space and light to grow them on.  Start tomatoes, peppers, aubergines, and celery, along with tender herbs like basil.

For faster spring growth, use the propagator to start leeks, brassicas, lettuce, and beetroot before moving them to a greenhouse or cold frame for planting out later.

Use the warmth to start half-hardy annuals and bedding plants for summer colour. Top choices include lisianthus, cosmos, cleome, nicotiana, calendula and tagetes. For bedding try erigeron, petunia, lobelia, marigolds, gazania, verbena, salvia or ageratum. If you want flowers for cutting or borders sow dahlias, sunflowers, larkspur, delphiniums, verbena bonariensis and antirrhinums.

March gardening is about gentle preparation rather than rushing ahead - watching the weather, warming the soil and starting a few plants under cover. A final chance to plant bare-root fruit trees, bushes, and shallots or garlic sets. Over the next few weeks, a little restraint, preparation, and forward planning will set the stage for a far more productive growing season ahead.