Fertilising guide

How to fertilise Camas (Camassia quamash)— schedule & NPK

Also called Camas, Quamash, Common Camas, Blue Camas.

More about camas

About Camas

Camassia quamash · also called Camas, Quamash · flowering

A native North American bulb bearing tall spikes of violet-blue to deep blue star-shaped flowers in late spring. Historically a vital food source for many Indigenous peoples of the Pacific Northwest. Thrives in moist meadow soils and naturalises well in borders and prairies. Deer and rodent resistant. Hardy to zone 3. Not toxic to pets.

Growth habit: Bulbous perennial; upright clump-forming with strap-like basal leaves; produces tall racemes of loosely arranged star-shaped flowers on erect scapes

Watch for — Dry soil during spring growth: Drought stress during the growing season results in stunted flower spikes or failure to bloom. Plant in moisture-retentive soil and mulch well. If spring is dry, supplement with irrigation during the active growth period.

What fertiliser camas actually wants — and why

Camas 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 camas: 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 camas, 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 camas:

Generally not required in fertile garden soils. In poor soils, apply a balanced bulb fertiliser at planting in autumn and a light liquid feed in early spring as leaves emerge. Over-feeding is unnecessary and not recommended. 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 camas 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 camas

Use the bulb-feed label rate for camas; 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 camas first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the camas watering schedule.

Signs you are over-feeding camas

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

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 camas

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 camas 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 camas every few years so they are not competing for nutrients.

Organic vs synthetic feeds for camas

Organic options

Bonemeal worked in at planting plus a mulch of garden compost or well-rotted leaf-mould is the traditional, reliable approach for camas. 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 camas — frequently asked questions

What fertiliser does camas 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. Camas 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 camas?

Generally not required in fertile garden soils. In poor soils, apply a balanced bulb fertiliser at planting in autumn and a light liquid feed in early spring as leaves emerge. Over-feeding is unnecessary and not recommended. Generally not required in fertile garden soils. In poor soils, apply a balanced bulb fertiliser at planting in autumn and a light liquid feed in early spring as leaves emerge. Over-feeding is unnecessary and not recommended. 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 camas?