Hardening off – Horticulturalist Peter Whyte gives some tips

May is traditionally the month when gardeners plant out the flower and vegetable crops they have started in the greenhouse.  Cabbage plants, courgettes, tender annual flowers and many more are planted outdoors, making way for the tomatoes and other heat-loving crops that will grow inside it for the summer.

On average most parts of the country will be free of frost after either the third week or the full moon of May, whichever is later.  Some years and some places are warmer than others.  But you can’t just move soft, quick-growing plants straight from the warmth of a tunnel or glasshouse to the rigours of an Irish garden in May without first getting them acclimatised to the great outdoors.

You prepare the plants by giving them cooler, drier conditions for a week or two before the move.  Their growth slows down and they become tougher and better able to cope with outdoor wind and weather.  On good days move the plants to a sheltered spot outside for a few hours: on bad days leave them inside the greenhouse but give them more ventilation.  Lift seed-trays by the middles of their long sides and not the corners, or the corners may break off.  Seed trays and pots can be grouped together on old tea-trays or oven shelves for convenience when carrying them in and out. 

Water the plants only enough to prevent them wilting.  When they are planted out they will be used to cold breezes and water stress, and will grow away better.  But after planting water them well until they resume growth, and keep something handy to put over them if you get one of those unseasonal late frosts.