How to: fix geraniums
We recognise that these are properly pelargoniums, but as most gardeners know them and love them as geraniums, that’s fine by us.
The most popular type are the zonals, identified by the ‘zones’ or patterns on their leaves. We also love ivy-leafed types for their indestructible nature and perfect hanging basket habit; and the scented geraniums whose foliage exhibits such a wealth of different fragrances.
No matter which you choose to grow, keep them in tip-top shape with this handy guide to common problems and remember to refresh your collection every few years with fresh cuttings.
Photo - Robin Powell
Geraniums need to be fed. Use either a controlled-release granular fertiliser such as Acticote for Roses or Osmocote for Flowering Plants every spring; or give a fortnightly application of liquid fertiliser such as Thrive, Powerfeed or Harvest, diluted following the instructions on the pack.
Orange dots on leaves
Yellow-orange spots or raised pustules on leaves are a fungal disease called rust. Treat and prevent this disease with either Yates Rose Gun or OCP Eco-fungicide. To reduce the risk of rust infection keep plants in a sunny spot with good airflow and only water from the base or saucer.
Sickly yellow leaves
Probably a sign of too much water: geraniums like it hot and dry – think Italian window boxes! Allow plants to dry out, trim them back and find a spot for them with excellent air circulation.
Give plants a good short, back and sides each year in late-winter. Through the growing season reduce the length of leggy stems by two-thirds. Use trimmings as cuttings to make new plants.
Frost causes geraniums to die back. They will reshoot again in the spring. Stems will often just drop off, but if they go mushy, give them a curt trim and a feed to encourage new growth.
Chewed holes in buds
This is the work work of bud grubs or caterpillars. Treat with Success, EcoNeem or Yates Rose Spray.
Brown, sunken spots in leaves
These are due to a bacterial leaf spot that is a common infection in the warm wet months. Remove damaged foliage and spray with a Liquid Copper fungicide or Eco-fungicide.
Grey fuzz on flowers
Pick off dead and dying flowers as they can often get a grey mould growing on them which looks like fur and makes the petals stick together. Bin the fallen flowers.
Refresh your geraniums every few years to keep them zooming along. For best results take cuttings in autumn, using pieces that aren’t too young or too long. Trim away the lower leaves and cut remaining leaves in half. Dip into hormone gel and insert into sterile potting mix. Put them somewhere light but not in direct sun, and don't let them dry out. Don’t cover them - they hate humidity.