Fertilising guide

How to fertilise Ithuriel's Spear (Triteleia laxa)— schedule & NPK

Also called Grassnut, Triplet Lily, Wally Basket.

More about ithuriel's spear

About Ithuriel's Spear

Triteleia laxa · also called Grassnut, Triplet Lily · flowering

Ithuriel's Spear is a California native cormous perennial producing loose umbels of violet to blue-purple star-shaped flowers on tall stems in late spring and early summer. Long-lasting as a cut flower. Naturalises beautifully in grassland or prairie-style gardens. Tolerates summer drought once corms are established. Toxicity to pets is uncertain — treat as mildly toxic.

Growth habit: Upright, slender cormous perennial with narrow basal leaves that die back before flowering peaks

Watch for — Floppy stems: Caused by insufficient sun or overly rich, fertile soil. Plant in lean, well-drained soil in full sun; stake only in very exposed sites.

What fertiliser ithuriel's spear actually wants — and why

Ithuriel's Spear 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 ithuriel's spear: 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 ithuriel's spear, 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 ithuriel's spear:

Apply a low-nitrogen, high-potassium bulb fertiliser at low rates in autumn when planting and in early spring as growth begins. Overly fertile soils produce lush foliage but reduce flowering. 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 ithuriel's spear 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 ithuriel's spear

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

Signs you are over-feeding ithuriel's spear

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

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 ithuriel's spear

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 ithuriel's spear 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 ithuriel's spear every few years so they are not competing for nutrients.

Organic vs synthetic feeds for ithuriel's spear

Organic options

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

What fertiliser does ithuriel's spear 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. Ithuriel's Spear 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 ithuriel's spear?

Apply a low-nitrogen, high-potassium bulb fertiliser at low rates in autumn when planting and in early spring as growth begins. Overly fertile soils produce lush foliage but reduce flowering. Apply a low-nitrogen, high-potassium bulb fertiliser at low rates in autumn when planting and in early spring as growth begins. Overly fertile soils produce lush foliage but reduce flowering. 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 ithuriel's spear?