Every spring there is a tension for us horticulturist about when to recommend you can plant your tender summer colour bedding plants into your pots, baskets and gardens. on the first sunny day every year at least half a dozen customers ask ‘Where are you petunias, geraniums lobelia etc?’ This is usually the question asked by someone wearing a fleece and a thick over coat because its so cold.
The reason being most summer bedding plants are ‘tender’ – they don’t like the cold. the question then becomes when and where will it be warm enough to plant away. This is compounded by that fact that these tender plants are also grown in heated greenhouses so that they are ready in sufficient quantities for all of us to plant when it’s the right time. Some plants such as Zonal Geraniums and Lobelia take months to grow even with heated growing condition. These plants then should be hardened off (weaned from the heat) before planting. In reality although this used to happen it’s too expensive to handle and harden off today so plants are very ‘soft’ when they leave the nurseries.
Many national multiple retailers send stock into there stores based upon an head office calendar. this take no account of the weather at the time and is often applied nationally so where you could plant in Cornwall in April you shouldn’t in Sheffield.
Many people focus on summer bedding plants being tender to frost, which is true, but just as important is the low night temperatures between 1-8C. at these temperatures. At these temperatures roots can die, especially if they are sodden. As you will read elsewhere in our site a plant with damaged roots can’t absorb water and thus nutrient and won’t thrive. It is always better to plant (or sow later) as later crops are planted in the warm weather and romp away surpassing your early crop. This is also applicable to tender vegetables such as tomatoes.
If you have a greenhouse, or conservatory that you don’t mind cultivating in, you can buy plants earlier say in late April or early May and plant your baskets and pots. This will give a head start but you will still need to ‘harden then off’ before final positioning. you can do this by bringing the pots and basket back in at night after the day time outside. Stand you basket on an empty pot at ground level to harden off. Never hang them straight up in the drying winds.
Tip if you can successfully garden in a tee shirt in the evening (and you are not from Newcastle) then you can provably plant your summer bedding outside. This will normally be in late May if you wondered.
Our advice for the best results is wait, plant summer bedding when it suit the plants in late May if it straight outside or early May if your are starting your planting inside a glass structure. If you want patio colour in April and May sue Pansies, violas, and the amazing Senetti.