How and When to Feed Geraniums

Feeding is one of the biggest levers you have over how well geraniums flower. Under-fed plants produce sparse, small blooms and pale foliage. Over-fed plants — especially with too much nitrogen — grow lush and leafy but carry very few flowers. Getting the balance right is straightforward once you understand what geraniums need at each stage of growth.

What nutrients geraniums need

Geraniums need a balanced supply of the three main nutrients — nitrogen (N), phosphorus (P), and potassium (K) — but the emphasis shifts depending on the season. In early spring as plants emerge from dormancy or are potted up, a balanced feed encourages strong stems and root development. From late spring onwards, switch to a high-potassium feed: tomato fertiliser works perfectly. Potassium promotes bud formation and intensifies flower colour without driving excessive leafy growth.

Feeding pelargoniums in containers

Container-grown pelargoniums are the most demanding as they rely entirely on what you provide. They deplete nutrients quickly, especially in the peak of summer when they are actively growing and flowering. A liquid high-potassium feed applied every one to two weeks from late spring through to early autumn is the standard approach. Always water the compost before applying liquid feed to a dry pot — applying to dry roots can scorch them.

• Start feeding when you see new growth in spring.
• Switch to high-potassium (tomato) feed from late spring.
• Feed every 7–14 days through summer.
• Stop feeding in September–October as growth slows.

Feeding geraniums in the ground

Hardy geraniums planted in borders are less feeding-intensive than container plants. In most garden soils with a reasonable organic matter content, no supplementary feeding is needed at all. If growth looks poor or foliage is pale, a single application of a general balanced granular fertiliser in spring is usually sufficient. Avoid feeding late in the season as this promotes soft growth vulnerable to early frosts.

Common feeding mistakes

Using a high-nitrogen fertiliser all season is the most frequent error. Nitrogen drives vegetative growth at the expense of flowers — you end up with a large, leafy plant that barely blooms. Feeding during winter dormancy is equally unhelpful and can stress overwintering plants. The other common mistake is irregular feeding: missing several weeks then applying a double dose. Steady, consistent feeding produces far better results than irregular heavy applications.