Advice
RHS Help & Advice
Keeping pelargoniums over winter
Pelargoniums are not winter hardy, but can be quite easily overwintered even without a heated greenhouse.
The
most reliable method of keeping pelargoniums over winter is
by taking cuttings in August and discarding the old woody
plants.
Rooted
cuttings can be kept on a windowsill in a well lit and frost-free
room from mid-September. Water sparingly until January, allowing
the compost to dry out between waterings. Start feeding in
January as plants come into growth, using a liquid feed every
7-10 days. Pinch out shoot tips in February, to encourage
bushy growth. Pot up in April or earlier if space is available.
Old
plants can be kept if they are lifted before the first frosts
and potted up in a John Innes No 1 compost.
Cut back growth in November to 10cm (4in), removing leaves. Keep plants in a light, frost-free position, e.g. cool greenhouse, well-lit garage, or unheated room. Very little water is needed until growth starts in spring. Pot up in April.
Less reliable methods which can be used for varieties with tough woody stems are wrapping in newspaper or hanging.
Lift plants and shake surplus soil from the roots and allow the foliage and stems to dry before wrapping in a couple of layers of newspaper. Alternatively, hang plants upside down in an airy frost-free shed. With both of these methods plants which survive and show signs of growth should first have their roots soaked in water for a few hours before potting up and cutting back shoots to about 10cm (4in) from the main stem.