Feeding Is a Matter of Balance

Fruit trees are patient things. Plant one and it will quietly get on with the business of rooting, thickening and fruiting without much help from you at all. But give it the right food at the right moment and you'll notice the difference — bigger crops, better colour, cleaner flavour and fruit that keeps far longer in store. Give it the wrong food, or too much of a good thing, and you'll grow a magnificent leafy tree that produces a disappointing handful of small, tasteless fruit.

That's the heart of it: feeding fruit trees is not about piling on the nutrition, it's about steering the tree's energy. Nitrogen pushes leaves and shoots. Potassium fills and flavours fruit. Get the balance right through the season and the tree does the rest.

What a Fruit Tree Actually Wants

Three nutrients do the heavy lifting. Nitrogen (N) drives leafy growth in spring and keeps the tree building new wood. Phosphorus (P) supports root development and the early stages of flowering and fruit set, though most UK soils hold plenty. Potassium (K) is the fruit-maker — it governs fruit size, sugar levels, colour and how well the crop stores.

Beyond the big three, fruit trees appreciate a few extras:

• Magnesium — a shortage shows as yellowing between the veins of older leaves, common on light or sandy soils. A scatter of Epsom salts in spring usually sorts it.
• Calcium — important for keeping quality, especially in apples. Bitter pit and corky patches are often a calcium problem, usually caused by irregular watering rather than a genuine soil shortage.
• Trace elements — iron and manganese matter most on chalky, alkaline ground, where leaves may yellow while the veins stay green.

Most garden soils supply these adequately. If you mulch generously with well-rotted manure or garden compost each spring, you're already covering a great deal of the tree's needs.

The Spring Feed: Growth Before Fruit

Late February to mid-March is the moment for the main feed of the year. The tree is waking, roots are active and the sap is beginning to move, so nutrients applied now will be available exactly when the new growth needs them.

Use a balanced general fertiliser — growmore, or an organic blood, fish and bone — scattered evenly over the root area, which extends roughly as far as the branches. As a rule of thumb, give a handful per year of the tree's age, up to a maximum of about four handfuls for a mature tree. Work it lightly into the surface with a fork and water it in if the ground is dry.

Young and newly planted trees need less, not more. If you prepared the planting hole properly with compost, hold off feeding altogether in the first spring — rich fertiliser around tender new roots can do real damage. From the second year onwards, a modest spring feed is plenty.

Early Summer: Switching to Potash

Once the fruit has set and is beginning to swell — usually June into July — change tack. This is when potassium earns its keep, so switch to sulphate of potash, a light dusting of wood ash from untreated timber, or a potassium-rich liquid feed such as comfrey. If you grow trained trees in pots or against a wall, a weekly tomato-type liquid feed at half strength through the summer does the job well.

Stop feeding by the end of July. Late nitrogen encourages soft, sappy growth that won't harden off before winter and is a magnet for aphids and canker.

How to Feed Without Waste

A few practical points make all the difference to how much of that fertiliser actually reaches the tree:

• Clear a ring of grass and weeds around the trunk — an area at least 60cm across for young trees, wider for established ones. Grass is a hungry competitor.
• Water thoroughly in dry spells while fruit is swelling. Fertiliser in dry soil is simply fertiliser you've wasted.
• Mulch after feeding with a 5–8cm layer of compost or manure, keeping it clear of the trunk itself.
• Never feed onto frozen or waterlogged ground. Wait for a milder, drier spell.
• Check the label and weigh or measure rather than guessing — a heaped handful is not a standard unit.

The Commonest Mistake: Too Much of a Good Thing

Overfeeding is by far the most frequent error, and it's an easy one to make with the best intentions. A glut of nitrogen gives you long, weak, sappy shoots, dark leaves and a tree that looks magnificent in July and disappoints in September. The crop, if there is one, is smaller, paler and often prone to bitter pit and poor storage. Soft growth also invites aphids, woolly aphids and canker.

A useful check is shoot growth. On a mature apple or pear, a leader should extend roughly 30–45cm in a season. Much more than that suggests excess nitrogen; much less, on a young tree, may mean it needs a little more. If your tree is already growing strongly, skip the spring feed entirely for a year and simply mulch instead.

Feed the soil, watch the tree, and adjust. That's the whole art of it — and your fruit will taste all the better for it.