How Do I Feed and Fertilise My Currant Bushes?

Currant bushes produce a large volume of fruit relative to their size, and to do so season after season they need a consistent supply of nutrients from the soil. Unfed bushes gradually exhaust the nutrients around their roots, producing smaller crops of increasingly poor-quality fruit. A simple annual feeding programme costs little and takes minutes but makes a dramatic difference to how productive your bushes remain over the years.

The main spring feed

Apply the main annual feed in late winter or early spring — late February to March — just as the buds begin to swell. A balanced general fertiliser containing nitrogen, phosphorus, and potassium is suitable. Sulphate of potash at 15–20 g per square metre, combined with a nitrogen fertiliser such as dried blood or a proprietary fruit fertiliser, gives good results. Alternatively, a handful of fish, blood, and bone per bush scattered over the root zone will supply all three main nutrients in organic form. Rake or lightly fork the fertiliser into the top few centimetres of soil and water it in if the soil is dry.

Nitrogen for blackcurrants

Blackcurrants need more nitrogen than redcurrants or white currants because they regenerate their entire fruiting framework from young shoots each year. A dedicated nitrogen feed — sulphate of ammonia at about 35 g per square metre, or a high-nitrogen liquid feed applied in May — gives the bushes an extra push to produce the vigorous young growth that will carry next year's crop. Avoid overdoing nitrogen on redcurrants as excessive soft growth is more susceptible to aphid attack and powdery mildew.

Potassium for fruit quality

Potassium (potash) improves fruit flavour, colour, and keeping quality, and helps harden growth against cold. Sulphate of potash is the traditional choice. Wood ash scattered around the base of the bushes also supplies a useful amount of potash alongside trace elements. Avoid using muriate of potash (potassium chloride), which can scorch fruit bushes at higher rates.

Mulching to feed and retain moisture

A generous mulch of well-rotted garden compost or manure applied in late winter, kept clear of the stems themselves, releases nutrients slowly through the season while also suppressing weeds and retaining soil moisture. This is particularly valuable in dry summers when unfed, dry bushes produce small, flavourless fruit. Apply a layer of 5–7 cm over the root zone each year.

Signs of nutrient deficiency

Yellowing leaves, especially between the veins, can indicate magnesium or iron deficiency in acid soils. Poor fruit set and weak new growth suggest nitrogen shortage. Small, poorly coloured fruit that tastes bland may indicate potassium deficiency. If deficiencies persist despite regular feeding, check the soil pH — most currant nutrient problems are related to pH that is too high or too low rather than a shortage of the nutrient itself. Currants prefer a slightly acid to neutral soil, around pH 6–6.5.