Fertilising guide

How to fertilise Yardlong Bean (Vigna unguiculata subsp. sesquipedalis)— schedule & NPK

Also called Asparagus bean, Snake bean, Chinese long bean.

More about yardlong bean

About Yardlong Bean

Vigna unguiculata subsp. sesquipedalis · also called Asparagus bean, Snake bean · edible

Yardlong bean (Vigna unguiculata subsp. sesquipedalis) is a heat-loving climbing relative of the cowpea grown for its remarkably long, slender pods that can reach 40-90 cm. A tropical annual, it thrives in hot summers, twining vigorously up tall supports. Pick pods young and tender for stir-fries; it tolerates heat far better than common green beans.

Growth habit: Vigorous twining annual climber producing pairs of extremely long, pencil-thin hanging pods; needs tall, strong supports.

What fertiliser yardlong bean actually wants — and why

Yardlong Bean 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 yardlong 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 yardlong 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 yardlong bean:

Low feeding needs thanks to nitrogen fixation; compost at planting is usually enough. In poor soil a light balanced feed early on helps establishment, then ease off nitrogen. 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 yardlong 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 yardlong bean

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

Signs you are over-feeding yardlong bean

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

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 yardlong bean

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 yardlong bean 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 yardlong bean 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 yardlong bean

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 yardlong bean — frequently asked questions

What fertiliser does yardlong bean 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. Yardlong Bean 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 yardlong bean?

Low feeding needs thanks to nitrogen fixation; compost at planting is usually enough. In poor soil a light balanced feed early on helps establishment, then ease off nitrogen. Low feeding needs thanks to nitrogen fixation; compost at planting is usually enough. In poor soil a light balanced feed early on helps establishment, then ease off nitrogen. 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 yardlong bean?

What does over-feeding yardlong bean 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 yardlong bean 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 yardlong bean?