What you can sow this month outside - or inside now for planting outside later:
In modules under cover without heat, or in a cold frame - (covering with fleece on frosty nights) or under cloches - or when the soil is dry enough and has warmed up later in the month, unprotected in the open, you can sow:
Beetroot, broad beans, carrots, mangetout and early peas, parsnips, late spring and summer cabbages, red cabbage, early Brussels sprouts, cauliflowers, calabrese and summer sprouting broccoli, onions (plant onion sets in pots for an early crop), leeks, spring onions, lettuces, kohl rabi, Ragged Jack and Cavolo Nero kales for baby leaves, radishes, Swiss chard, summer spinach, white turnips, American land cress, lamb's lettuce, salad mixes, 'soft' herbs like borage, parsley, dill, fennel, greek oregano and coriander. There's a lot of nonsense talked about germinating parsley, but it just likes to be warm and usually takes about 3 weeks to germinate anytime of year - it always appears just when you think it's not going to!
It's also worth sowing some single, early flowering annuals in the open ground or in modules - such as limnanthes (poached egg plant), calendula, cerinthe, convulvulus tricolor, borage, red clover and phacelia. They'll attract beneficial insects to help with pest control, encourage bees into the garden for pollination and also look beautiful - which is very important too.
What you can sow now for growing in the polytunnel or greenhouse - In a heated propagator
(for growing later in the tunnel)
Aubergines (early in the month - Bonica F1 is best - top of RHS trials & AGM several years ago), alpine strawberries (Reugen a great var.), globe artichokes, (if sown early in the month, they'll crop outside in autumn this year), dwarf French beans for cropping in pots or in tunnel beds later (choose a fast growing, disease-resistant variety suitable for early sowing), asparagus, celery, celeriac (early in month) tomatoes, chillis and other peppers, physalis (Cape gooseberries), from mid-March on early courgettes and then later in the month melons and cucumbers for warm tunnel cropping. Don't forget melons and cucumbers need to be grown on in consistently warmer conditions than tomatoes to be successful - they grow very fast and hate to be checked (this applies to pumpkins & squashes too - wait until next month to sow them in pots for outside). Also sow some single-flowered more tender annuals now like Tagetes, French marigolds (T&M 'Tall Citrus Mixed' is good), etc.- these attract many beneficial insects which will help with pest control and pollination. It's really important that they are SINGLE flowered, as bees, hoverflies and other insects can't get at the nectaries of double flowers to feed - so they are completely useless to them - they then have to fly elsewhere to find food. When their energy supplies are low, wasting time trying to get nectar from useless flowers can make the difference between life and death for many small insects!
In modules in the tunnel without heat, or direct in tunnel soil as soon as you feel it's warm enough
(if weed seeds are germinating - it is for most things that don't need very high temperatures for germination) - you can sow:
Beetroot, broad beans and peas, spring and summer cabbage, calabrese, carrots, white turnips and radishes (in the soil for an early tunnel crop), onions, chives, Welsh (perennial salad) onions, scallions, leeks, lettuces and salad mixes early in the month, kales, rocket, spinach and coloured Swiss chards etc for baby leaves, fennel and 'soft herbs' like borage, parsley, dill, Greek oregano, salad burnet and coriander.
Other single flowered annuals like limnanthes, convulvulus tricolour and calendula can also be sown direct into the soil in beds now. Keep an eye out for hungry mice - they love pea and bean seeds - it's a good idea to put down a trap - but be careful to avoid trapping small birds like wrens and robins.
If you have space now in the tunnel or greenhouse where you'll be planting tomatoes in May - then you just have time to sow a useful green manure mustard called Caliente (see my article in The Irish Garden magazine - March 2016)
The best variety is 'Caliente' (generally availabl
e now, or from Marshalls and Unwins seeds - one packet will easily sow a bed about 20ft x 4ft.) This mustard acts as a 'biofumigant' by releasing a natural plant phytochemical as a gas - isothiocyanate. This suppresses a range of soil borne diseases and harmful nematodes - it also encourages beneficial bacteria and soil micro-organisms, adds nutrients and really encourages worm activity. It's particularly helpful where the soil has previously grown tomatoes before. A couple of weeks before planting the tomatoes - cut it down - chopping it up as finely as possible in order to release all it's beneficial compounds and dig it in immediately - before the resulting gases escape. Then cover it with black polythene to seal gases in. (see this month's polytunnel section) As it's a brassica - make sure it fits into your minimum 4-course rotation even though it will only be there for a short time. Phacelia is another fast growing 'soft' green manure worth sowing now if you have space - this can also be dug in after just one months growth, will break down quickly and it isn't rotation sensitive, so it can be used anywhere. Leaving one or two plants to produce their pretty blue flowers later on will really bring in the insects too! Red clover is also useful, it fixes 'free' atmospheric nitrogen which it concentrates in nodules on it's roots made by beneficial microbes, then releases it for the following crop (leave a few to flower for bees - they adore them!). Borage also makes a good, very fast growing green manure with a long tap root which draws up valuable minerals such as magnesium from lower down in the soil profile - it breaks down easily when dug in and encourages good worm activity, as does claytonia (winter purslane).
There's still just time to plant garlic early in the month. Only plant varieties clearly labelled as 'suitable for spring planting''now - such as 'Cristo'.
Plant Jerusalem artichokes and also early potatoes in warm well drained soils protecting from frost with fleece later (see veg. garden section). These will crop early enough to completely avoid blight. If your ground conditions aren't suitable - you could alternatively start them off in pots for an early crop - I do this with all of mine now. You can also start off Yacon, Oca and Ulluco tubers inside in pots now for planting outside or inside later - protect carefully from frost!
Don't forget that these are just suggestions for what you could sow now - not what you must! I found a checklist like this invaluable when I was just starting many years ago. (Someone once complained that I give too much information!) So I thought I'd make that quite clear! You can't please everyone - and all the information is free!
AND REMEMBER MY ADVICE. IF YOU'RE SHORT OF TIME - JUST GET THE SEEDS SOWN! YOU CAN CATCH UP WITH EVERYTHING ELSE LATER BUT NOT THAT! TIME WAITS FOR NO MAN! (Or woman!)
Funny that we spend our time wishing away winter - then wishing everything would happen more slowly in spring - gardeners are never happy!
(P.S. I really enjoy sharing my original ideas and 40 years experience of growing and cooking my own organic food with you. It's most satisfying and naturally also very complimentary if others find "inspiration" in my work......But if you do happen to copy any of my material, or repeat it in any way online - I would appreciate it very much if you would please mention that it originally came from me, as it's the result of many years of hard work and often hard won-experience. Thank you.)