I have noticed a lot of confusion, amongst new gardeners especially, about the plants you buy for summer colour for your pots, window boxes and hanging baskets. For several weeks, tempting displays of colourful summer flowers have been visible outside all manner of retail outlets, from petrol stations to supermarkets, and it’s perfectly reasonable to think that if they are for sale, it’s safe to plant them out in the garden – but plant them too soon and you could kill them, and here’s why.
Most of the plants used for that summer splash of colour are annuals – meaning they last for one season only, enjoying a brief but gloriously colourful life. Annuals can be hardy or half- hardy. Hardy annuals don’t mind frost, and they include cornflower, nasturtium, sweet peas, calendula and nigella – seeds of these can all be sown outdoors in late spring. Half-hardy annuals are different – frost will kill them, and we can get frost in Ireland right up to the middle of May and beyond – so these are sown and grown indoors under cover, only being planted outside when all risk of frost has passed. Half hardies make up most of the ‘summer colour’ plants that you buy for your containers – among them would be petunia, begonia, lobelia, nemesia, tagetes and bidens. Some bigger half hardies that you might pop into borders include nicotiana, zinnia and cosmos. Plant any of these outdoors too soon and a late frost can severely damage or even kill them.
It’s very tempting to stock up on colourful half-hardies when you see them, but clever gardeners will keep them inside for now– if you don’t have a greenhouse or polytunnel, a porch or a patch of the hall floor will do. Pop them outside during the day to ‘harden off’ for a week or two – gradually acclimatising them to outdoor conditions, and bring them back inside as night falls. It’s a bit of a faff but that week or ten days of care will make all the difference to the summer display you will get to enjoy for months to come!
ANNE’S TIP OF THE WEEK:
If you have plants outside that could be at risk from frost, invest in a few metres of horticultural fleece from your local garden centre to spread over them at night until risk of frost has passed. Secure with tent pegs or bricks and remove in the mornings so that light and air can reach the plants during the day.
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Anne Byrne Garden Design – Creative Ideas – Practical Solutions – Stunning Gardens
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