In the greenhouse ​​ 
 

• Start sowing half-hardy annuals like cosmos, zinnia and amaranthus. They are tender and cannot be planted out until after all risk of frost has gone. 
   

• With seed sowing in full swing, it's important to keep pricking out and potting on seedlings to maintain plant health. Prick out seedlings from seed trays once they have their first pair of true leaves and transfer to individual pots or cell trays.
   

• Seedlings can quickly outgrow their allotted space -  small white roots emerging from the holes in the bottom of a pot or cell tray are a tell-tale sign that the plant needs re-potting into something bigger. Check on any cuttings taken in the autumn - they will probably need potting on with fresh compost at this point. 
   

• Tidy up overwintered scented geraniums by refreshing soil and cutting back. Use the cut material to propagate new plants  - treat them as you would any softwood cutting - potting them into free draining compost and using a little rooting powder to encourage them on their way. A heated propagator or heat mat will speed the process up. Alternatively you can put the cut stems into water and they will send 
  out roots. 
   

• Pot up any plants bought as rooted cuttings into small pots to grow on before planting out later.   

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Bulbs, tubers, corms & claws

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• It's still possible to get hold of ranunculus claws and anemone corms, just. Start them off by soaking first in water overnight and then 'pre-sprouting' in a seed tray of 50/50 compost/vermiculite in a propagator or on a heat mat (or put them in a plastic bag in the airing cupboard). Once the roots are an inch or so long, pot them on into 9cm pots or 15-cell trays in the greenhouse.
   

• It's still possible to get hold of bare root dahlias, but be quick as they won't be around for much longer. Pot them up when they arrive and keep them somewhere frost free.
   

• If you are intending on taking cuttings from your existing dahlias to increase stock, pot the tubers into 5L pots or a seed tray (depending on the size of the tuber).  It's much easier to take cuttings later if the top couple of inches of the tubers are above soil level, so don't submerge them completely. The pots will need to go on heat mat or propagator in the greenhouse. Alternatively you can divide your existing dahlias to create more plants. 
   

• Plant summer/autumn flowering bulbs such as lilies, gladioli, nerine and acidanthera.
   

• Once daffodils, muscari and other spring bulbs have finished flowering in the garden, deadhead any you haven't already cut. Allow the leaves to die by naturally to allow photosynthesis to occur. 

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​In the garden

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• Direct sow hardy annuals like ammi, cornflower, poppies and nigella. Thin the sowings later in the month. 
   

• Continue to prepare beds by clearing the last of any dead foliage from perennials (if you haven't already) and pulling out any weeds. Perennial weeds are much easier to tackle now as the roots won't have had a chance to properly take hold yet. Once clear, mulch with a thick layer of homemade compost or manure.
   

• Plant out autumn or winter sown sweet peas. Ideally a couple of weeks before, make a special effort to prepare the area where you will plant them out - they will flourish the extra effort of digging in plenty of manure and general fertiliser. Install the support system before to planting.
   

• Plant out hardy annuals like cornflowers, ammi, wild carrot and orlaya. Acclimatise them well to conditions outdoors by 'hardening' them off properly to give them a fighting chance once they're out in the garden. If a hard frost is forecast you can use horticultural fleece to protect them if necessary. 
   

• Create plant support and structures from willow/hazel. Use poles cut back in mid winter whilst the plant was still dormant. Anything cut later will sprout once in the ground. 
   

• Divide any congested clumps of perennials such as Delphiniums, sedum (hylotelephium) or ornamental grasses. It's a good time to buy small pots of perennials to plant out as they are cheap at this time of year - they will bulk up quickly if planted now and offer good value for money. 
    

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