Getting it to bloom

Why won't my Crocus tommasinianus 'Ruby Giant' bloom? (and how to make it flower)

Also called Ruby Giant crocus, Tommie crocus, purple Tommasinianus crocus (Crocus tommasinianus 'Ruby Giant').

More about crocus tommasinianus 'ruby giant'

About Crocus tommasinianus 'Ruby Giant'

Crocus tommasinianus 'Ruby Giant' · also called Ruby Giant crocus, Tommie crocus · flowering

Crocus tommasinianus 'Ruby Giant' is an early, slender 'Tommie' crocus bearing rich reddish-purple, silvery-backed flowers in late winter to early spring. Sterile but vigorous, it spreads by offsets to naturalise quickly in lawns and gravel. Plant corms 7-10 cm deep in autumn in full sun and free-draining soil; it is famously squirrel-resistant compared with larger Dutch crocus.

Plant type: flowering

Watch for — Flowers closed in dull weather: Blooms open only in sun and warmth, staying shut on grey late-winter days. Plant in the sunniest available spot for the longest display.

The reasons crocus tommasinianus 'ruby giant' isn't blooming

Almost every non-blooming crocus tommasinianus 'ruby giant' traces back to one of these, roughly in order of how common they are:

Bulbs were not chilled long or cold enough (a problem in mild winters or with un-chilled forced bulbs).
The winter was too mild or the plant too sheltered to bank enough chill hours.
Foliage was cut down too early last year, so the bulb could not recharge for this year’s bloom.
Too little sun during the growing season to build the reserves the flower needs.
Excess nitrogen feed driving leaf at the expense of flower.

Skipping the cold period (or buying un-chilled bulbs in a mild climate). Without real vernalisation there are no flowers.

The fix — how to get crocus tommasinianus 'ruby giant' to flower

Let it get genuinely cold. Leave crocus tommasinianus 'ruby giant' outdoors (or in an unheated, cold spot) through winter — do not mulch heavily or shelter it from the cold it needs.
Chill the bulbs properly. Use pre-chilled bulbs, or give 12-16 weeks of cold (around 4-9 °C / 40-48 °F) before planting in mild climates.
Feed the foliage, then leave it. Let leaves grow and feed the plant after flowering; never cut foliage down until it yellows naturally.
Be patient after any move. Expect a settling year (or two to three for peony) with few or no flowers after planting or division — this is normal, not failure.

Light and feeding do most of the heavy lifting here. Dial in the spot with the light guide for crocus tommasinianus 'ruby giant' and get the feeding right with the crocus tommasinianus 'ruby giant' fertilising schedule — the wrong feed (too much nitrogen) is one of the most common silent reasons a healthy plant makes leaves instead of flowers.

Bloom season and what to expect

Crocus tommasinianus 'Ruby Giant' flowers in its season (typically spring for chilled bulbs) once the cold requirement is met, then dies back to recharge for next year.

Post-bloom care so it flowers again

Let the foliage die back fully before tidying — it is recharging the bulb. A light feed after flowering supports next year's display.

For everything else this plant needs day to day, see the full crocus tommasinianus 'ruby giant' care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Crocus tommasinianus 'Ruby Giant' blooming — frequently asked questions

Why won't my crocus tommasinianus 'ruby giant' flower?

Crocus tommasinianus 'Ruby Giant' needs a real cold period (vernalisation) to flower — the winter chill is the signal that ripens the bud inside the bulb or crown. The most common reason it is not happening: Bulbs were not chilled long or cold enough (a problem in mild winters or with un-chilled forced bulbs).

How do I make crocus tommasinianus 'ruby giant' bloom?

Leave crocus tommasinianus 'ruby giant' outdoors (or in an unheated, cold spot) through winter — do not mulch heavily or shelter it from the cold it needs. Use pre-chilled bulbs, or give 12-16 weeks of cold (around 4-9 °C / 40-48 °F) before planting in mild climates.

When does crocus tommasinianus 'ruby giant' normally bloom?