Over-wintering your Pelargoniums
Pelargoniums are such a diverse group of plants. Some very large and some very tiny. From tough to very delicate. There are Pelargoniums for most situations, remembering of course that despite our best wishes, they are not hardy.
Basic growing requirements.
One definition of a Pelargonium is it’s a tender perennial, so this gives you a pretty good idea of what the plant will need. The 3 most important factors are - good light, airflow & a frost free environment. I have no idea where the idea came from that pelargoniums can survive in a garage or garden shed through the winter. If they do, it’s chance rather than design.
So, the most asked question is, “what to do with Pelargoniums in the winter”. It is the most critical time of the year. Before winter though, to do the best to ensure their survival the plant itself needs some preparation.
Timing is important. Preparing the plant too late in the season can mean failure. So the best time to start is the end of September. This gives the plant time to recover and grow away.
Start by cutting the plant back by half, just above a leaf joint, whatever the size. This material can then be used for propagating by cuttings if you want. Then remove all the leaves from the remainder of the plant. This helps to remove any insects or their eggs that might be thinking of overwintering on the undersides of the leaves. It also increases airflow around the stems, which is vital.
At this point it would also be a good idea to spray with a general fungicide to prevent botrytis from setting in. The plants themselves will shoot out again in a short time so don’t feel you’re being too harsh on them. When this happens it is time to give them a little fresh compost for the winter. It can be a slightly bigger pot, or if space is short, brush compost from around the roots and repot back into the same pot. Water well, place in good light & keep frost free. A minimum temperature here is +5c over night. If you struggle to keep this temperature then you must keep the plant drier and hope for the best.
Watering during the winter is important, it's more to do with observation than anything else. Water well into the top of the pot when you do. It is best not to get water on the foliage, choosing a dry sunny day if possible. Then leave as long as possible between watering, allowing the compost to dry out before you water again.
The plant should grow slowly over the winter period. Once the day length increases it starts to grow more rapidly. Therefore watering increases from say a little every two weeks to once a week and by the end of February you should be able to give it it’s first feed. The first feed of the year should be a general feed rather than a high potash feed. It gives the plant a spring boost and helps it through recovery, although a pelargonium does not need too much nitrogen as this encourages it to make too much leaf, so after this you should switch to a high potash feed, weekly. By March we can finally see which of our plants have survived the winter. From our collection it's good news and bad news as usual. Some plants will only just be starting to shoot. This is quite late, but in Pebworth we generally don’t have good light and Pelargoniums need light. What to do now. Some plants will still be looking a bit frail. So with these it's gently does it. Start by removing dead leaves and cut away stems that have died back. Note here don't cut into new green stems at the moment. The plant has made a natural seal and if you make an open wound this can start to die back again. Water well and leave until the leaves look fresher and brighter. If you have a plant that looks particularly frail and you try and repot it, or feed it to try and make it grow the shock can sometimes finish it off completely. Much better to take it slowly, if it's going to recover, it will do so in its own time .
Come the end of March and your plant can really start to grow fast, it’s a good time to cut it again. Firstly to get it into a good shape and also to take extra cuttings should you need them. This also helps with the problem of lack of space, as it can’t go into the garden until May! Once your pelargonium has started to grow away well, it is ready for its spring re-pot. This may well need to be into a larger pot but you must remember, pelargoniums don’t like lots of wet compost around their roots so pot accordingly. A Miniature does not need a large pot, however some Scented-Leaf varieties can be thugs so need room.
Finally I think it's all about watching your plants and looking for the signs. A bright green leaf means it's growing, a dull blue green means it's not started yet. Above all be guided by what the plant is telling you and we might be able to get even more plants through the winter to enjoy the following year.
And please don't think that there are rules. There aren't. If you successfully overwinter your pelargoniums using your own methods, then carry on doing what you're doing. This is just a guide.
Time is short, so chop chop and go get your Pellies tidied up for the winter.