Fertilising guide
How to fertilise Hyacinth bean (Dolichos lablab)— schedule & NPK
Also called Hyacinth bean, Lablab bean, Egyptian bean, Indian bean, Bonavist bean.
More about hyacinth bean
About Hyacinth bean
Dolichos lablab · also called Hyacinth bean, Lablab bean · edible
Hyacinth bean is a fast-growing tropical vine that combines ornamental drama with edible value. Deep purple pods and fragrant lavender flower racemes make it a striking warm-season annual in temperate gardens. Young pods and leaves are edible when cooked; mature dried seeds contain cyanogenic glycosides and must be thoroughly boiled before eating. Grows 3–6 m in a single season with full sun and support.
Growth habit: Fast-growing twining perennial vine grown as a warm-season annual in temperate climates
What fertiliser hyacinth bean actually wants — and why
Hyacinth bean feeds for next year, not this one — the critical window is after flowering, while the leaves are still green and recharging the bulb.
A low-nitrogen, potassium- and phosphorus-leaning bulb fertiliser (something like 5-10-10) or bonemeal at planting. High nitrogen grows floppy leaves and rots stored bulbs.
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 hyacinth bean: 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 hyacinth bean, 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 hyacinth bean:
Apply phosphorus-rich fertiliser (e.g. 5-10-10) at planting. As a nitrogen-fixing legume, avoid high-nitrogen feeds — they promote excessive leafy growth at the expense of pods and flowers. A light high-potash feed monthly once flowering begins supports pod development. The rhythm: a bulb feed at planting, a light feed as leaves emerge, and — most important — a potassium feed straight after flowering while the foliage is still green and feeding the bulb. Never cut the leaves off early.
The dormant-season rule matters more than the exact interval: skip feeding entirely when hyacinth bean 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 hyacinth bean
Use the bulb-feed label rate for hyacinth bean; the timing (post-bloom, leaves still green) does far more for next year's display than the concentration.
Feeding always goes onto already-damp soil, never dry roots — water hyacinth bean first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the hyacinth bean watering schedule.
Signs you are over-feeding hyacinth bean
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for hyacinth bean:
- Tall, floppy, soft leaves that flop over (too much nitrogen).
- Soft or rotting bulbs lifted at the end of the season.
- Lush foliage but few or poor flowers.
Signs you are under-feeding hyacinth bean
- Progressively fewer or smaller flowers year on year ("going blind").
- Small, weak bulbs and thin foliage.
- Bulbs that fail to come back at all after a few seasons.
If the symptoms point at watering, light or roots rather than nutrition, the full hyacinth bean care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Bulbs are not container-flushed like houseplants; the equivalent is not over-feeding and lifting/dividing congested clumps of hyacinth bean every few years so they are not competing for nutrients.
Organic vs synthetic feeds for hyacinth bean
Organic options
Bonemeal worked in at planting plus a mulch of garden compost or well-rotted leaf-mould is the traditional, reliable approach for hyacinth bean. UK: blood, fish & bone or Westland Bulb Food; US: Espoma Bulb-tone or bonemeal.
Synthetic / liquid feeds
A proprietary bulb fertiliser at planting and a high-potash liquid (tomato feed) after flowering — UK: Westland Bulb Food then Tomorite; US: Miracle-Gro Shake 'n Feed Bulb or a bloom booster post-flower.
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 hyacinth bean — frequently asked questions
What fertiliser does hyacinth bean need?
A low-nitrogen, potassium- and phosphorus-leaning bulb fertiliser (something like 5-10-10) or bonemeal at planting. High nitrogen grows floppy leaves and rots stored bulbs. Hyacinth bean feeds for next year, not this one — the critical window is after flowering, while the leaves are still green and recharging the bulb.
How often should I feed hyacinth bean?
Apply phosphorus-rich fertiliser (e.g. 5-10-10) at planting. As a nitrogen-fixing legume, avoid high-nitrogen feeds — they promote excessive leafy growth at the expense of pods and flowers. A light high-potash feed monthly once flowering begins supports pod development. Apply phosphorus-rich fertiliser (e.g. 5-10-10) at planting. As a nitrogen-fixing legume, avoid high-nitrogen feeds — they promote excessive leafy growth at the expense of pods and flowers. A light high-potash feed monthly once flowering begins supports pod development. The rhythm: a bulb feed at planting, a light feed as leaves emerge, and — most important — a potassium feed straight after flowering while the foliage is still green and feeding the bulb. Never cut the leaves off early.
What strength of feed for hyacinth bean?
Use the bulb-feed label rate for hyacinth bean; the timing (post-bloom, leaves still green) does far more for next year's display than the concentration.
What does over-feeding hyacinth bean look like?
Tall, floppy, soft leaves that flop over (too much nitrogen). Soft or rotting bulbs lifted at the end of the season. Lush foliage but few or poor flowers. Cutting or tying off the leaves of hyacinth bean as soon as the flowers fade is the great bulb mistake — the bulb recharges through those leaves for weeks afterward, and removing them early means a weak or blind display next year.
Should I flush the soil of hyacinth bean?
Bulbs are not container-flushed like houseplants; the equivalent is not over-feeding and lifting/dividing congested clumps of hyacinth bean every few years so they are not competing for nutrients.
Keep reading
- Hyacinth bean care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water hyacinth bean — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
- How to fertilise european hazel 'cosford'
- How to fertilise european hazel 'nottingham prolific'
- How to fertilise european hazel 'witchford'
- All 6887 fertilising guides in the Growli library