Fertilising guide

How to fertilise Red Durian (Durio dulcis)— schedule & NPK

Also called Red-fleshed Durian, Lahong, Durian Merah.

More about red durian

About Red Durian

Durio dulcis · also called Red-fleshed Durian, Lahong · edible

Red Durian is a large tropical rainforest tree native to Borneo producing spectacular deep crimson-fleshed fruits with a notably sweet, caramel-like flavour and a much milder odour than Durio zibethinus. It demands a consistently hot, humid tropical climate. Not individually listed by ASPCA; classified mildly toxic as a precaution for pets.

Growth habit: Large canopy tree with a straight trunk and spreading crown

Watch for — Fruit drop before maturity: Water stress, nutrient deficiency, or pollination failure causes premature drop. Maintain consistent irrigation and potassium supply.

What fertiliser red durian actually wants — and why

Red Durian 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 red durian: 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 red durian, 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 red durian:

Apply a balanced organic fertiliser (such as composted manure) twice yearly. During fruiting, supplement with a high-potassium feed. Durios are sensitive to fertiliser burn; always water before and after application. 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 red durian 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 red durian

Follow the crop-feed label rate for red durian — 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 red durian first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the red durian watering schedule.

Signs you are over-feeding red durian

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

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 red durian

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 red durian 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 red durian 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 red durian

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 red durian — frequently asked questions

What fertiliser does red durian 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. Red Durian 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 red durian?

Apply a balanced organic fertiliser (such as composted manure) twice yearly. During fruiting, supplement with a high-potassium feed. Durios are sensitive to fertiliser burn; always water before and after application. Apply a balanced organic fertiliser (such as composted manure) twice yearly. During fruiting, supplement with a high-potassium feed. Durios are sensitive to fertiliser burn; always water before and after application. 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 red durian?

What does over-feeding red durian 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 red durian 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 red durian?