Repotting guide

When & how to repot Pelargonium citronellum (Pelargonium citronellum)

Also called Citronella geranium, Mosquito plant, Lemon pelargonium.

More about pelargonium citronellum

About Pelargonium citronellum

Pelargonium citronellum · also called Citronella geranium, Mosquito plant · herb

Pelargonium citronellum is a robust scented geranium with rough, deeply lobed leaves that smell strongly of lemon-citronella when touched. Often sold as the 'mosquito plant', its fragrance does not actually repel insects in the air. A tall, vigorous South African species, it bears pink flowers and demands full sun, sharp drainage and a frost-free winter.

Mature size: 80-120 cm tall and 60-90 cm wide; among the larger scented geraniums and can reach 1.2 m or more if unpruned.

How to tell pelargonium citronellum needs repotting

Repotting on a calendar is less reliable than reading the plant. For pelargonium citronellum, watch for these signs:

Roots growing out of the drainage holes, or the rootball lifting the plant proud of the rim.
Soil that has shrunk away from the pot sides and no longer holds water.
The pot is unstable because the plant has grown top-heavy.
Old, compacted, broken-down mix that stays wet too long — for a succulent that is a rot risk, so refresh it even if the pot size is fine.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot pelargonium citronellum

Every 2–3 years, into bone-dry mix. Pelargonium citronellum's growth habit — tall, vigorous, upright evergreen subshrub with stiff stems and large, rough, sharply lobed lemon-scented leaves; can become woody and benefits from hard pinching and pruning. — sets the pace. Pelargonium citronellum is a robust scented geranium with rough, deeply lobed leaves that smell strongly of lemon-citronella when touched. Often sold as the 'mosquito plant', its fragrance does not actually repel insects in the air. A tall, vigorous South African species, it bears pink flowers and demands full sun, sharp drainage and a frost-free winter.

What size pot to step pelargonium citronellum up to

Use a pot only one size up — or even the same pot with fresh gritty mix if the roots have room. Pelargonium citronellum stores water and rots in a large pot of slow-drying soil. A tight terracotta pot that dries fast is far safer than a generous plastic one. Never up-pot a succulent by several sizes.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot pelargonium citronellum

Spring or summer, while pelargonium citronellum is in active growth and warm, is best — roots recover fastest then, and the plant is not sitting in cool damp soil. Avoid repotting a succulent in winter dormancy.

Step-by-step: repotting pelargonium citronellum

Repot dry. Do not water pelargonium citronellum for several days first. Working with dry roots and dry mix dramatically lowers the rot risk for a succulent.
Pick a snug, fast-draining pot. Choose terracotta one size up at most, with a drainage hole. Have gritty free-draining loam or potting mix with added grit or perlite ready.
Tip it out and clean the roots. Slide the plant out, crumble off the old soil, and trim any black, mushy or dead roots with clean snips.
Pot into dry mix. Set pelargonium citronellum at its original depth in dry gritty mix, firming gently. Do not bury the stem deeper than it was.
Wait a week before watering. Leave it completely dry and out of harsh sun for about 7 days so any damaged roots callus. Only then water lightly.

Aftercare

Keep pelargonium citronellum completely dry and out of fierce sun for about a week so any nicked roots callus before they meet moisture; watering a freshly repotted succulent is the classic way to rot it. Then resume the normal lean, dry rhythm. Do not fertilise for about 3 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for pelargonium citronellum

Pelargonium citronellum wants free-draining loam or potting mix with added grit or perlite. Gritty, sharply drained peat-free compost. Tolerates poorer, leaner soils; neutral to slightly alkaline pH is ideal. Avoid heavy, moisture-retentive mixes. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting pelargonium citronellum — frequently asked questions

How often should you repot pelargonium citronellum?

Every 2–3 years, into bone-dry mix for pelargonium citronellum. Repot pelargonium citronellum every 2–3 years into a snug pot of free-draining loam or potting mix with added grit or perlite, ideally in spring or summer. Let it sit in dry soil and do not water for about a week afterwards so any nicked roots can callus. Over-potting and watering straight away is what rots succulents.

What size pot does pelargonium citronellum need?

When is the best time of year to repot pelargonium citronellum?

Should you water pelargonium citronellum after repotting?

No — not straight away. Repot pelargonium citronellum into dry mix and wait about a week before the first watering so any damaged roots callus over. Watering a freshly repotted succulent is the single most common way to rot one.

Should you fertilise pelargonium citronellum after repotting?

Not immediately. Wait about 3 weeks after repotting pelargonium citronellum. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.