Watering
Water your pelargoniums every two to three days during their active growing season.
Take care to water sparingly during the winter, when the plants are undercover. If kept at 7-10ºC (45-50ºF), plants may continue to grow right through the winter. Otherwise cut back your plants by two-thirds and keep them almost dry until they begin to shoot in the spring, when regular watering can start again.
Fertilising
Feed your pelargoniums with a homemade feed of comfrey juice or organic liquid plant food – both rich in potash – every fortnight while in flower.
Deadheading
Deadheading pelargoniums regularly helps prolong flowering – do this more often during rainy periods because damp spent flower heads could become susceptible to botrytis. To deadhead, snap the flower off where it joins the stem.
Propagating
Propagating pelargoniums from cuttings is easy. If you propagate them rather than growing on last year’s plants, you'll have more floriferous and stronger plants.
Start propagating pelargoniums in September, while plants are in an active stage of growth. They will root very quickly.
To do this, take a cutting that’s about (1½-3in) long using a very sharp knife. Remove any lower leaves or flower buds and the leader (the apical shoot). Insert the cuttings around the edge of a pot filled with a mix of two-thirds peat free multipurpose compost to one-third grit.
Do not cover your pelargoniums (as you might when propagating other tender perennials). Leave them somewhere warm, ideally on a heated mat or warm windowsill, and keep the compost moist.
They should root within two to three weeks. You'll know they have done so by new growth at their tips and new white roots at the base of the pot.
Keep them frost free and just moist through the winter, and pot them on into individual pots in early spring. They'll grow fantastically and you'll have lots of plants to put out in the garden in summer.
Some pelargoniums can also be grown from seed but they will need to be started early in spring in a heated propagator.
Overwintering
If your pelargoniums are in the ground, lift the plants out, pot them up and bring them inside before the frost. If they are already in pots, bring them undercover. A greenhouse or potting shed is good, or you could bring them indoors as winter houseplants.
If kept at 7-10ºC (45-50ºF), plants may keep growing and even flowering right through the winter. Otherwise cut back your plants by two-thirds. They don’t go into complete dormancy, so water lightly through the winter until they begin to shoot in the spring, and then more regular watering can start again.
In spring, begin feeding and increase watering. Plant out only once any danger of frost has passed.
It’s worth noting, that at Perch Hill, we’ve found that in a very sheltered spot, varieties such as ‘Attar of Roses’ will get singed by frost, and look half dead, but if you leave the frost-burnt tops on the plants as a sort of mulch, the plants often survive the winter outside and grow off bigger and better in spring. This is great for foliage for flower arranging, but they won’t flower as much as newly rooted cuttings.
