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Last updated 06/4/20 13:35.
Geranium - Growing Guide
Caring for Herbaceous Geraniums – Cranesbill
Cranesbills are generally long lived and versatile plants which are undemanding and easy to grow well. That may perhaps make for a rather short care article on this particular subject but there are still a few tips which you need to know to get the best results.
There are 300 species of cranesbill but the ones we are dealing with here are mainly semi-evergreen perennials. They are not to be confused with pelargoniums which are often (incorrectly) referred to as geraniums. Cranesbills have been bred and improved enormously in recent decades to improve the size and colour of their flowers, their flowering span, and to produce more compact habits. The list of new varieties is massive and it was no accident that the RHS Chelsea Centenary Plant of the Year was the then new Geranium ‘Rozanne’ which has sold in many hundreds of thousands since worldwide with breeders rights.
Cranesbills are mostly compact perennials which grow to only 12-15in tall although there are plenty of varieties that grow a bit taller (G. ‘Wargrave Pink’, G. pratense, G. ‘Ann Folkard’). They make wonderful groundcover within taller growing border plants to inhibit weeds. The more dwarf growing forms (G. renardii, G. nodosum, G. sanguineum) which grow only to say 6-8in are more suitable for rockeries or edging a border. Some varieties will naturalise in the woodland garden away from a border and many perform well in such situations (G. ‘Johnson’s Blue’, G. sanguineum ‘Album’, G. ‘Wargrave Pink’).
The key tip to remember is that when your cranesbill has finally finished its lengthy flowering season (and may be starting to set seeds) you should give the plant a good chop back to remove the old flower stems and leaves. This will rejuvenate the plants and encourage the production of new leaves and, perhaps, a secondary flowering later in the summer. The taller growing varieties seem to benefit most from this treatment which is easy enough by hand or with secateurs.
If you grow lots of herbaceous geraniums in your garden collecting seeds will produce a mixture of varieties. It is far better to lift and divide the clumps when they are dormant in winter to produce new plants. Similarly most will propagate from early season cuttings with bottom heat.
Cranesbills will tolerate poorish soils in full sun or shade but not waterlogged ones. Outdoors they benefit from a liquid feed as they get started and an autumn mulch may help keep the weeds down while they are dormant.
Brief mention must be made of two popular tender species of geranium which sell well from the nursery and which will just about survive outside in the mildest coastal locations in Cornwall but which are really greenhouse plants.
Geranium maderense and Geranium palmatum are both robust evergreen species which are not frost hardy unlike all the other varieties which we offer. It is time now to let the pictures of these beautiful plants tell the story of how to grow them in open beds or pots in a frost free greenhouse or conservatory.
Lifting & splitting - Video Tip
- GERANIUM 'Ann Folkard'
- GERANIUM 'Brookside'
- GERANIUM 'Johnson's Blue'
- GERANIUM 'Rozanne'
- GERANIUM himalayense
- GERANIUM macrorrhizum 'Ingwersen's Variety'
- GERANIUM maderense
- GERANIUM nodosum
- GERANIUM palmatum
- GERANIUM phaeum
- GERANIUM pratense 'Mrs Kendall Clark'
- GERANIUM renardii
- GERANIUM sanguineum
- GERANIUM wallichianum 'Buxton's Variety'
- GERANIUM x oxonianum 'A.T. Johnson'
- GERANIUM x riversleaianum 'Russell Prichard'