Towards the end of May, all risk of frost has passed in most areas of the country, and it’s therefore safe to put tender plants outside. But if you take them straight outside from a warm greenhouse, cool night temperatures can still scorch leaves and winds may tear them.
So, by gradually getting plants used to outside temperatures by putting them out during the day, then protecting them at night, you can help acclimatise them to the new environment. Do this over a week to a fortnight, and use a max-min thermometer to monitor temperatures.
Take fuchsias, flowering annuals and pelargoniums outside first, followed by beans, courgettes and tomatoes for the veg garden. Wait another month to ensure tropical plants survive. Houseplants can be moved out for some air in the warmest months, while melons, squash and sweetcorn should be planted later when the ground is warmer.
Be aware of regional differences – frost-free nights occur from mid-May in the south to mid-June in the north, but late frosts may still occur so it’s important to check the weather forecast.