Now’s the time to repot or ‘top dress’ and spring clean houseplants. They can last for 2-3 years before repotting but it pays to check annually. Knock your plants from the pot, to see if they are ‘pot bound’ – soaking the root-ball for half an hour in tepid water makes it easier to remove them from the pot, though you may need to slide an old kitchen knife between the pot and the root-ball to ease it out. If repotting is needed, transplant into a pot one or two sizes larger. Terracotta pots should be soaked overnight and given a good scrub and plastic pots should be washed with a little detergent and bleach and rinsed thoroughly. Put a layer of broken terracotta, polystyrene pieces or bottle corks in the base to help drainage, tease out some of the roots from the root-ball then re-fill around it, firming the compost in layers with your fingers or the end of a bamboo cane, as you go, don’t plant too deeply and leave a gap between the rim of the pot and compost for watering. Finally, top-dress the surface with gravel or fine bark mulch to conserve moisture and discourage fungus gnats which like organic compost. Water thoroughly, allow plants to recover in the shade for a few days then put them back display. If your plants don’t need re-potting, top dress by carefully removing the top 2.5cm of compost with an old culinary fork and replace with new compost mixed with slow release fertiliser. Brush the dust from hairy leaves with a make-up brush and wipe glossy leaves with a soft damp cloth, gently supporting them below so they are not damaged. Don’t wipe new leaves. Wiping is not always practical It is easier to put larger plants outside for a wash in the spring rains when the weather gets warmer or wash them in the shower with a gentle jet of tepid water and your plants will be in tip top condition for the new growing season.
Among the methods available for controlling slugs which are becoming more active in the warmer weather are biological control nematodes, ‘slug pubs’ made from jam jars or margarine tubs buried with the rim 15mm above the soil, so other slug predators like ground beetles are not accidentally drowned, then fill the container with stout or ale. Check them regularly and empty as required. Try slug hunting in the evening and pick them off the plants; lie sacking, roof tiles, upturned grapefruit or lettuce leaves on the ground then removing from their hiding places. Encourage natural predators like hedgehogs, frogs toads or slow worms or try copper tape round the rim of a pot or raised bed. Make ‘collars’ cut from plastic drinks bottles and put them around your seedlings. Finally, try grit, crushed oyster shell or Aluminium sulphate or Ferric phosphate pellets (don’t spread them densely; follow the manufacturer’s instructions) and wool pellets.
Keep pots of bulbs well-watered on sunny days as the combination of sunshine and drying wind soon dries out the compost. Feeding at the same time with tomato fertiliser once a fortnight from blooming until the leaves die back ensures the bulbs are ready for flowering next year.
Happy Gardening. Matt