How Do I Feed Roses for the Best Flowers?

Roses are among the most nutrient-hungry garden plants, and regular feeding is one of the most effective ways to improve both the quantity and quality of the flowers they produce. An unfed rose may survive for years but will produce progressively fewer, smaller blooms as the available nutrients in the surrounding soil are exhausted. A well-fed rose, by contrast, produces vigorous healthy growth and an abundance of large, deeply coloured flowers throughout the season.

The spring feed

Apply the first feed of the year in early spring, around the time of the main annual prune in late February or March. Use a proprietary rose fertiliser or a balanced granular fertiliser with a roughly equal NPK ratio. Scatter the granules around each plant at the manufacturer's recommended rate, keeping them away from the stems, and lightly fork them into the soil surface. Water in if the soil is dry. This feed provides the nutrients needed for the first season's growth and the initial flush of flowers.

The midsummer feed

After the first flush of flowers in early summer, apply a second feed to fuel the next wave of flowering. This is particularly important for repeat-flowering roses which need to sustain multiple flowering cycles through the season. A proprietary rose fertiliser applied after the first deadheading in June or July replenishes the nutrients used in the first flush and promotes stronger, more abundant subsequent flowers. Granular or liquid fertilisers both work well — liquid feeds act faster but need more frequent application.

Potassium and flower quality

Potassium (potash) is the nutrient most directly associated with flower colour, scent, and petal size in roses. Sulphate of potash scattered around plants in spring and again in midsummer, at about 20 g per square metre, noticeably improves bloom quality compared with nitrogen-only feeding. Wood ash is a useful organic source of potash but should be used in moderation as it raises soil pH. Rose fertilisers are formulated to contain adequate potash alongside nitrogen and phosphorus.

Foliar feeding

A dilute liquid fertiliser applied to the leaves as a foliar spray is absorbed much faster than soil-applied feed and can provide a quick boost during the growing season. Seaweed extract is a popular choice for foliar feeding roses — it supplies a range of micronutrients and plant hormones that support strong growth and flowering. Apply foliar feeds in the early morning or evening to avoid scorching in hot sun, and do not apply to water-stressed plants.

When to stop feeding

Stop feeding roses after mid-August. Feeding after this point encourages new soft growth that will not harden off before the frosts and is vulnerable to cold damage. Late feeding also delays the plant going into dormancy, which leaves it less well prepared for winter. The last feed of summer should be a potassium-rich one to harden growth before the autumn.

Mulching as a slow feed

An annual mulch of well-rotted garden compost or farmyard manure applied around roses in late winter slowly releases nutrients through the season while improving soil structure and moisture retention. This works as a complement to, not a replacement for, the spring and summer feeds.