It’s important to make arrangements for someone to look after your smaller houseplants while you‘re on holiday. Ideally ask a neighbour who’s keen on gardening. If your kitchen draining board is away from scorching sunshine, group all your houseplants there, write down the instructions clearly on a piece of paper or stick the instructions on the side of each pot and take them through their individual needs before you leave. Alternatively, stand them all on an old towel or capillary matting with one end dipped in a sink full of water to act as a wick; single plants can be watered using a wick of a cotton shoelace or a piece of wool. They can also be put outdoors in a shady spot outdoors – houseplants enjoy a holiday too and can stand outdoors once the danger of frost has passed and be brought in before the first frosts of autumn.
Japanese onions are among the best for over wintering and should be sown from mid-August. The timing is critical, sow too early and they ‘run to seed‘, too late and they won’t survive the winter. Sow from mid to late August, depending on whether you are in the north or south of the country. The seeds should be 2.5cm apart and the rows 30cm apart, rake a high nitrogen fertiliser into the seedbed before sowing and top up the nitrogen again in spring for the highest yields. ‘Express Yellow OX‘ and ‘Buffalo‘ are two excellent varieties, if you‘ve never tried them before, I‘m sure you‘ll be impressed.
Late summer is the ideal time to collect seed hardy and half-hardy annuals. Don‘t bother with F1 hybrids that won’t come ‘true‘ from seed, concentrate on species like Nicotiana sylvestris, ‘Love in a Mist‘ and annual poppies that flower ‘true to type‘. Towards the end of the flowering season, keep a close watch on the seed pods and start collecting as soon as they start to split. Cut off the seed heads carefully so that you don‘t loose the seeds and put them into paper bags or an enveloped marked with the name of the plant and when the seed was collected or put the pods on a tray. When the seeds have dried, keep them in envelopes in a draw or sealed in a glass jar with some silica gel, anywhere cool and dry until next spring when you start sowing.
From mid summer, rhododendrons and camellias are forming their flower buds for next year‘s display and it‘s absolutely vital that the compost or soil around them doesn‘t dry out or they will not form buds or shed those they already have. During dry periods, check them daily plants daily and water them thoroughly if necessary, using stored rain water a mulch with well rotted organic matter really helps when the soil is moist in spring, so put that in your diary for spring next year! Those in pots are particularly vulnerable and may need watering twice a day. The indoor azaleas that you‘ve been growing outdoors for next winter’s display will need the same treatment too but should be watered with soft, tepid water.