Pelargonium Care Guide

Pelargonium Care Guide — How to Grow Strong, Healthy Plants

Pelargoniums are not difficult plants, but they do have particular preferences.
Once you understand how they grow in the wild, caring for them becomes simple — warmth, light, good air movement and a free-draining compost are the keys to success.

This guide covers everything from watering and feeding to overwintering, pruning and dealing with common problems.

Light & Position

All Pelargoniums need as much light as possible in the winter months. A greenhouse, conservatory or bright, cool windowsill is ideal during the darker part of the year.

In summer, however, not every Pelargonium wants full, strong sun.
Most enjoy bright, warm conditions, but certain species — such as P. tomentosum — can scorch or wilt in intense heat, and plants like P. ardens or P. triste will go dormant if kept too hot.

Avoid deep shade, as plants will quickly become leggy, but equally avoid placing sensitive species where they may burn.

Compost & Potting Mix

Pelargoniums dislike heavy or compacted compost.

They grow best in a coarse, open mix that lets plenty of air reach the roots and doesn’t collapse as it ages.

Peat-free compost can pose challenges, as many mixes tend to compact over time — something Pelargoniums resent.
Adding bark or perlite helps keep the structure open, improving airflow and drainage.
A small amount of John Innes or loam can help the compost hold moisture more evenly, but avoid using pure John Innes or loam-based mixes, as these are too heavy for Pelargoniums.

One thing to remember about peat-free composts is that they do not dry out evenly. They often dry from the top down, which can be misleading.
Do not rely on the look of the compost surface when judging whether a plant needs water. Instead, learn to check below the surface by:

  • judging the weight of the pot
  • using a moisture meter, or
  • tapping the pot and listening to the sound it makes

With a little practice, you’ll quickly recognise when the compost is dry enough to water again.

Watering — The Most Important Skill

If Pelargoniums struggle, watering is usually the reason.
They are tolerant of drought but suffer if kept cold and wet.

General rule:

Warm = water more.
Cool = water less.

Spring & Summer

  • Water thoroughly when the pot has dried out.
  • Avoid overhead watering, especially indoors (wet leaves invite botrytis)
  • In hot weather, established plants may need watering every other day

Autumn

Begin reducing water gradually as temperatures fall.

Winter

Pelargoniums should be kept on the dry side during cold months.

Approximate guide:

  • December–January: light watering every 2–3 weeks
  • February: once a week as growth restarts
  • Young plants always need less than big established specimens

If in doubt—do not water.
Pelargoniums are far more forgiving of dryness than damp.

In winter, water on a bright morning so any splashes dry before nightfall.

Temperature & Overwintering

Pelargoniums are frost-tender. Most will tolerate cool nights but not freezing.

Ideal winter temperature: 5–10°C

Cool, bright and dry is perfect.

Where to overwinter

  • Greenhouse kept frost-free
  • Cool conservatory
  • Bright porch
  • Spare room with good light
  • NOT next to radiators, stoves or damp bathrooms
  • NOT dark garages or sheds

Ventilation matters

Good airflow reduces fungal problems. Even in winter, open vents or a window for a short period on dry days.

Feeding

Pelargoniums respond well to feeding during active growth.

In summer

Feed every 1–2 weeks with a high-potash feed (like Tomorite).

Avoid high-nitrogen fertilisers

They make the plants leafy and soft, increasing the risk of pests and weak growth.

Slow-release fertilisers

Can be mixed into compost for larger specimens.

Species Pelargoniums

Need far less feeding — enjoy them for their form and leaf character rather than flower quantity.

Pruning & Pinching Out

Pruning is essential if you want neat, sturdy, floriferous plants.

In spring and early summer

  • Pinch out growing tips regularly
  • This encourages strong, woody growth and prevents leggy-ness

In autumn

  • Cut plants back hard to improve light penetration and airflow
  • Always cut back to a node; never leave a bare stub above it
  • Use the foliage you remove to take cuttings to make new plants.

Group differences

  • Regals: naturally bushy, little pinching needed
  • Decoratives: prone to sappy, leggy growth — pinch often
  • Scented & Uniques: mixed behaviour; some lax growers need extra attention
  • Angels: mostly compact; a few require regular stopping

Proper pruning keeps plants tight, balanced and productive.

Repotting

Repot between February and October.

Choosing the right pot size

Pelargoniums hate being overpotted.

  • Vigorous species (e.g. P. tomentosum) → pot straight to 11cm
  • Slow or compact types → start smaller (7cm)
  • Never pot a small rooted cutting into a large pot
  • When a plant reaches its final size, remove it from the pot each year, trim away some old fibrous roots, and replant in the same pot with fresh compost

Repot established plants once a year.

Deadheading & Leaf Tidying

Deadheading

  • Encourages repeat flowering
  • Prevents seed formation (which halts new blooms)
  • Essential in winter when spent flowers turn to botrytis magnets

Removing yellow leaves

Do not try to remove the entire leaf stem.
Pinch off the leaf blade cleanly — the stalk will dry and fall away naturally.

Pests & Problems

Pelargoniums are generally robust, but some issues can occur:

Whitefly

Especially loves regals, decoratives, and citrus-scented types.
Control with:

  • Regularly spray with SB Invigorator but avoid doing so in bright light. 
  • Good ventilation
  • Outdoors placement in summer to encourage natural predators

Botrytis (Grey Mould)

Thrives with:

  • Poor ventilation
  • Damp leaves
  • Winter gloom

The solution:

Dry atmosphere, clean pruning, tidy leaves regularly, ventilate daily.

Rust

Mostly affects Zonal Pelargoniums.
Look for orange spores under leaves.
Remove affected leaves carefully and dispose of them in a sealed bag.

Black Leg (Pythium)

Affects unrooted cuttings or waterlogged young plants.
Check trays regularly and remove any stems showing blackening at the base.

Propagation

Pelargoniums root readily from cuttings.

Take cuttings:

  • March–April
  • August–September

How to take perfect cuttings

  • Choose fresh, non-flowering growth
  • Take nodal cuttings where possible
  • Trim large leaves to reduce transpiration
  • Insert into a fine compost with added perlite.
  • Use plug trays to reduce disease spread
  • Provide good light but not direct sun, avoid high humidity
  • Rooting usually takes 4-6 weeks in spring

Above all — enjoy them

Pelargoniums reward good care with fragrance, form, endless flower and a sense of summer even in the dullest weather.
They are one of the most generous plants you can grow, and with a little understanding, they’ll thrive for years.