Botanical name: Pelargonium x hortorum
Geraniums are a popular houseplants due to their ease of care, large colourful blooms and a long flowering period. They will bloom almost all year-round if kept on a sunny window at average room temperature. However, they hate being overwatered. The Pelargonium x hortorum is a hybrid between Pelargonium zonale and Pelargonium inquinans. It belongs to the group of Pelargoniums called Zonal (or common) Pelargonium. This refers to the brown annular zone around the leaves. They grow to a height of 1-2 ft but some can reach 4 ft or more. The parent plants are native to South Africa. The whole plant except the flowers gives off a characteristic smell. Numerous varieties of Pelargonium x hortorum are available. Some have small insignifact flowers and are grown for their colourful foliage but majority bear large flowers which may be single, semi-double or double. The common colours are white, red, pink, orange and purple.
Geranium prefers bright light with some direct sunlight. Geranium will not bloom if the light is not enough. Learn how to ensure your plant receives the correct light in this guide on understanding light for houseplants
Keep the soil moist at all times for Geranium and allow the top 1-2 in. of soil to dry out between waterings. Reduce watering during the cold period. Avoid waterlogging as it can lead to Root-rot Disease. Learn more on how to water houseplants.
Average warmth with a minimum of 130C is ideal for Geranium. Cool nights and warm days are necessary to trigger flower buds. Protect the plant from cold and hot draughts. Learn more on temperature for houseplants.
Average room humidity is ideal for Geranium. Set the pot on a wet pebble tray to raise humidity if the air is too dry. Do not mist the leaves as it can lead to fungal diseases.
Feed Geranium with a phosphorous-rich water-soluble fertilizer every 3-4 weeks during the growing season. Withhold feeding in the cold season as growth is minimal and it can lead to fertilizer burn. Find out more on how to feed houseplants.
Repot Geranium during the growing season only when the plant is extremely pot-bound; it blooms more when pot-bound. Do not repot a plant that is in flower. Use a pot 1 size larger and one that has a drainage hole to prevent waterlogging as it can lead to Root-rot Disease. The soil should be rich in organic matter and free-draining.
Pruning Geranium is easy. Remove dead flowers and leaves to maintain the plant neat and tidy. Pinch off the growing tips to encourage compact growth and prevent the plant from getting unruly. After flowering, lightly cut back the stems to rejuvenate growth and keep the plant compact. Learn more on how to prune houseplants.
Geranium can be propagated at the beginning of the growing season from stem cuttings or by seeds.
Propagating Geranium from stem cuttings
Take a 4-6 stem cuttings from a healthy Geranium plant. Insert the cuttings in moist free-draining soil. Place the set up in a warm well-lit spot. Maintain the soil moist through out until the new plants are well established.
Propagating Geraniums from seeds
Spread Geranium seeds evenly on moist free-draining soil and cover lightly with some soil. Cover the set up with a plastic sheet to create a greenhouse effect. Place the set up in a warm brightly-lit place. Maintain the soil moist through out by gently misting the soil surface until the seedlings are well established. When the seedlings are a reasonable size, transplant into individual pots. Place in a cool well-lit spot and maintain the soil moist until well established.
The cause of yellow, firm and scorched lower leaves in Geraniums is underwatering. Water Geranium thoroughly during the growing period and allow the soil to dry out between waterings but never allow the soil ball to dry out completely.
Overwatering is the cause of yellow, wilted and rotten lower leaves in Geraniums. Maintain the soil moist but not soggy.
Spindly growth and leaf drop in Geraniums is due to too little light. Geraniums prefer bright light but away from direct sunlight.
Very low temperature is the cause of reddening leaf edges in Geraniums. Move the plant to a warmer spot and protect it from cold draughts.
The cause of blackening of the stem base in Geraniums is Black Leg Disease which is enhanced by waterlogging.
Water-soaked corky patches of the leaves of Geraniums are an indication of Oedema Disease which is promoted by waterlogging.
Grey mold on leaves in Geraniums are a sign of Botrytis Disease which is associated with waterlogging.
Geranium (Pelargonium x hortorum) plants are non-toxic to humans and pets. They are known to be used in teas and cakes.