Fertilising guide

How to fertilise Greengage (Prunus domestica 'Reine Claude Dorée')— schedule & NPK

Also called greengage, Reine Claude, green plum.

More about greengage

About Greengage

Prunus domestica 'Reine Claude Dorée' · also called greengage, Reine Claude · edible

The greengage is a connoisseur's dessert plum bearing small, round, green-to-gold fruit with exceptionally rich, honeyed flesh. The original Reine Claude is only partially self-fertile and needs warmth and a sheltered, sunny wall to ripen well, rewarding patient gardeners in good summers with arguably the finest-flavoured plum of all.

Growth habit: Moderately vigorous, rounded, twiggy deciduous tree; often fan-trained against a wall for warmth. Cropping can be irregular year to year.

What fertiliser greengage actually wants — and why

Greengage feeds in two distinct phases — balanced to build the plant, then high-potassium the moment flowering starts to set and fill a heavy crop.

For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for greengage: match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.

How often to feed greengage, and which months

Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For greengage:

Feed a balanced fertiliser in late winter plus sulphate of potash in spring to support its often-shy cropping. Mulch with rotted manure annually. Avoid excess nitrogen, which delays fruiting and encourages aphids and soft growth. So: a balanced feed or compost at planting, then a high-potash liquid every 1-2 weeks from first flower through harvest across the main season (spring through early autumn).

The dormant-season rule matters more than the exact interval: skip feeding entirely when greengage is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.

What strength to mix for greengage

Follow the crop-feed label rate for greengage — these are calibrated for hungry vegetables. Consistency through fruiting matters more than strength; erratic feeding causes problems like blossom-end rot.

Feeding always goes onto already-damp soil, never dry roots — water greengage first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the greengage watering schedule.

Signs you are over-feeding greengage

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for greengage:

Vigorous dark-green leafy growth but few flowers or fruit (excess nitrogen).
Lush foliage hiding the crop; soft growth prone to pests and disease.
Salt crust on the soil and scorched leaf edges in containers.

Signs you are under-feeding greengage

Pale, yellowing lower leaves and stunted growth.
Small fruit, poor set, and a quickly exhausted plant.
Blossom-end rot and weak cropping from erratic or insufficient feeding.

If the symptoms point at watering, light or roots rather than nutrition, the full greengage care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

In containers, fertiliser salts build up fast — water greengage thoroughly so excess drains from the base each time, and flush pots with plain water every few weeks to prevent a damaging salt build-up.

Organic vs synthetic feeds for greengage

Organic options

Garden compost or well-rotted manure dug in before planting, plus a liquid comfrey or seaweed feed once fruiting starts. UK: comfrey feed or organic Tomorite; US: Espoma Tomato-tone or Neptune's Harvest. Builds soil and feeds in one.

Synthetic / liquid feeds

A balanced feed at planting then a high-potash tomato feed in fruiting — UK: Growmore at planting then Tomorite (Levington) or Phostrogen; US: a balanced 10-10-10 then Miracle-Gro Tomato or a bloom booster.

Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.

Fertilising greengage — frequently asked questions

What fertiliser does greengage need?

Balanced (even N-P-K) at planting for roots and frame, then switch to a high-potassium ("high-potash") tomato-style feed once the first flowers open — potassium is what sizes and ripens fruit, not nitrogen. Greengage feeds in two distinct phases — balanced to build the plant, then high-potassium the moment flowering starts to set and fill a heavy crop.

How often should I feed greengage?

Feed a balanced fertiliser in late winter plus sulphate of potash in spring to support its often-shy cropping. Mulch with rotted manure annually. Avoid excess nitrogen, which delays fruiting and encourages aphids and soft growth. Feed a balanced fertiliser in late winter plus sulphate of potash in spring to support its often-shy cropping. Mulch with rotted manure annually. Avoid excess nitrogen, which delays fruiting and encourages aphids and soft growth. So: a balanced feed or compost at planting, then a high-potash liquid every 1-2 weeks from first flower through harvest across the main season (spring through early autumn).

What strength of feed for greengage?

What does over-feeding greengage look like?

Vigorous dark-green leafy growth but few flowers or fruit (excess nitrogen). Lush foliage hiding the crop; soft growth prone to pests and disease. Salt crust on the soil and scorched leaf edges in containers. Staying on a high-nitrogen feed once greengage starts flowering is the classic error — you get a huge leafy plant and a disappointing crop. Switch to high-potash the moment flowers appear.

Should I flush the soil of greengage?