Advice
RHS Help & Advice
Feeding and mulching fruit trees
Fertilisers
Fruit trees need feeding to crop well. Nitrogen promotes foliage and vigorous growth; dessert apples need less than cooking apples and pears, while plums and cherries appreciate more. Phosphorus promotes healthy growth and fruit. Potassium is necessary for good fruit colour, flavour, hardiness and fruit bud development. How much feeding fruit trees need depends on the soil and can be adjusted depending on growth, cropping and soil analysis.
As a rule-of-thumb, feed apples and pears lightly, using 100g/sq m (3oz/sq yd) of general purpose fertiliser or, for organic gardeners, fish, blood and bone. Whichever one is used apply added potassium-rich fertiliser, sulphate of potash or an organic potassium material at 15g/sq m (0.5oz/sq yd). If cooking apples and pears have pale foliage, increase the general-purpose fertiliser by half. Double the general-purpose fertiliser for cherries and plums, and increase the potassium-rich fertiliser to 20g/sq m (0.75oz/sq yd).
These fertilisers should be applied at the end of February.
If using straight fertilisers apply at the following rates:
Nitrogen: Apply 35g per sq m (1oz per sq yd) of ammonium sulphate in spring each year. Dried poultry pellets are an organic alternative.Phosphorus: Apply 35g per sq m (1oz per sq yd) of superphosphate in winter every three to four years where required. Bonemeal is an organic alternative.
Potassium: Apply 15g per sq m (0.5oz per sq yd) of sulphate of potash every year. Too much potash may lead to magnesium deficiency and increase the risk of bitter pit in apples.
Mulches
An annual mulch of bulky organic matter after applying the fertiliser will benefit trees by reducing water loss and suppressing weeds, as well as providing some nutrients. Bulky organic materials include stable or farmyard manure, mushroom compost, spent hops, leafmould and garden compost.
Mushroom compost often contains chalk and as most fruit prefers acid conditions, it should not be used too frequently except on very acid soils. Do not apply to raspberries.
Straw can be used as a surface mulch to conserve moisture, but if it is incorporated into the soil it must be well rotted or, alternatively, extra nitrogen must be applied.
Pears, plums, gages and damson trees especially need additional water in the summer and will benefit from mulching. Newly planted fruit trees and cane fruits need regular watering and should be mulched to conserve moisture and promote strong growth. Red currants, white currants, gooseberries and raspberries are difficult to grow on light soils but benefit from mulching. Even with mulches you may need to water in dry spells.
Ideally, keep a grass-free zone, at least 1m (1yd) wide, around trees to reduce competition and allow mulching. Apples and pears appreciate a low-nutrient mulch - such as garden compost, while plums and cherries respond to richer rotted manure. Mulching can halve fertiliser needs and is ideal for organic growers.