Flowers & bulbs

How to Grow Geraniums (Pelargonium)

Quick answer

Transplant after all danger of frost is past and the soil has warmed (Clemson). These are Pelargonium (bedding/zonal geraniums), not hardy cranesbill Geranium. NC State: low severity poison — leaves; geraniol and linalool; GI upset; cats most sensitive. At least 4 hours of direct sun; well-drained soil; keep water off foliage.

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Updated

Pelargonium, not cranesbill. This page is bedding / zonal Pelargonium (often sold as “geranium”). Hardy cranesbill is a different genus (Geranium) — see hardy geranium (cranesbill). Poison: NC State rates Pelargonium × hybridum poison severity Low. Toxic principle: geraniol, linalool. Poison part: leaves. Symptoms: vomiting, anorexia when consumed in quantity; primarily GI upset; cats most sensitive; mild contact dermatitis possible. Do not ingest; keep away from pets. Not medical advice. (NC State Pelargonium × hybridum)

Bedding geranium (Pelargonium × hortorum)
Bedding geranium (Pelargonium × hortorum). Photo: David J. Stang, Wikimedia Commons, CC BY-SA 4.0 (resized).

Sourced from university extension guides. For dates where you live, use the ZIP planting planner.

Planting timing

Pelargonium bedding geraniums: Clemson HGIC 1164 — “Plant geraniums outdoors after all danger of frost is past and the soil has warmed.” (Clemson geraniums) NC State: plant outside after the last frost. Planner: Transplant last frost 0. No sourced national frost-week chart for starting seed indoors — NC mentions January–February on a heat mat for regional seed starts; cuttings are common. We do not invent a start-indoors frost-week rule.

Spacing and types

NC State: available space often less than 12 inches. Clemson: height from about 6 inches to several feet by type. ID groups only (no cultivar shopping list): zonal / common garden; ivy-leaf; scented-leaf; regal (Clemson). True hardy geraniums (cranesbill) are a different genus.

Sun, soil and water

Clemson: at least 4 hours of direct sun; midday shade in very hot areas; well-drained soil; water regularly but allow soil to dry between waterings; never allow plants to wilt; keep water off foliage. Mulch beds. Prefer compost; we omit printed synthetic fertilizer rates.

Care and bloom

Deadhead to prolong flowering; pinch for branching (Clemson). Overwinter options exist (cuttings, dig/pot, or cool dormant storage) — optional for annual bedding use. Purdue HO-80 bloom window about May–September for planning.

Toxicity

NC State: poison severity Low; leaves; geraniol and linalool; GI upset; cats most sensitive. (NC State)

Pests and diseases

Clemson: bacterial leaf spot/blight; Botrytis in cool moist weather; edema from overwatering — reduce watering frequency, keep water off leaves, air circulation, enough sun. Insects: aphids, caterpillars, mites, whiteflies. Aphids: soap or oil with thorough coverage (UC IPM aphids). Use any product as the label directs.

Related: hardy geranium (cranesbill) · ZIP planner · organic pest control · petunia

Frequently asked questions

When do I plant bedding geraniums outside?

After all danger of frost and once the soil has warmed (Clemson).

Are garden geraniums the same as cranesbill?

No. Bedding types are Pelargonium; hardy cranesbill is Geranium (Clemson).

Are pelargoniums poisonous?

NC State low severity — leaves; geraniol/linalool; GI upset; cats most sensitive. Do not ingest.

Sources