Getting it to bloom

Why won't my Big-Flowered Catmint bloom? (and how to make it flower)

Also called Big-Flowered Catmint, Large-Flowered Catmint (Nepeta grandiflora).

More about big-flowered catmint

About Big-Flowered Catmint

Nepeta grandiflora · also called Big-Flowered Catmint, Large-Flowered Catmint · flowering

Big-Flowered Catmint is a robust, tall-growing species from the Caucasus bearing long racemes of large, deep violet-blue flowers from midsummer into autumn. Taller and later-blooming than most catmints, it is superb at the back of mixed borders. It is highly attractive to bumblebees and other long-tongued pollinators, and is reliably deer-resistant.

Plant type: flowering

Watch for — Powdery mildew in late season: Can affect foliage after the main flush. Cut stems back to 15–20 cm post-bloom; fresh foliage emerging in autumn is typically mildew-free. Good plant spacing helps.

The reasons big-flowered catmint isn't blooming

Almost every non-blooming big-flowered catmint traces back to one of these, roughly in order of how common they are:

Too little sun — most of these need full sun (or very bright light) to flower well; shade gives leaves, not blooms.
Too much nitrogen feed, driving lush foliage at the expense of flowers (very common with general or lawn feeds).
The plant has not been deadheaded, so it stops flowering once it sets seed.
Irregular watering — drought or waterlogging at the budding stage makes buds abort.
It is still too young or was checked by a transplant and is rebuilding before flowering.

Feeding big-flowered catmint a high-nitrogen general feed and growing it in too little sun — you get a big leafy plant and almost no flowers.

The fix — how to get big-flowered catmint to flower

Maximise sun. Give big-flowered catmint the sunniest spot you have — for most bedding and fruiting plants, more direct light directly means more flowers.
Switch the feed. Move off high-nitrogen feeds and use a higher-potassium "bloom" or tomato-type feed as it comes into flower.
Deadhead regularly. Remove spent flowers often to keep it producing more rather than stopping to set seed.
Water consistently. Keep moisture even through budding and flowering — drought-then-flood swings make buds drop.

Light and feeding do most of the heavy lifting here. Dial in the spot with the light guide for big-flowered catmint and get the feeding right with the big-flowered catmint 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

Big-Flowered Catmint flowers across its growing season (mostly summer) and, kept fed and deadheaded, can bloom for many weeks or right up to frost.

Post-bloom care so it flowers again

Deadhead, keep feeding lightly, and many will rebloom; collect seed from the best plants at the end of the season if you want to grow them again.

For everything else this plant needs day to day, see the full big-flowered catmint care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Big-Flowered Catmint blooming — frequently asked questions

Why won't my big-flowered catmint flower?

Big-Flowered Catmint blooms on the season's growth given enough sun, warmth and the right feed — there is no cold or photoperiod trick, just good growing conditions and a bloom-leaning feed. The most common reason it is not happening: Too little sun — most of these need full sun (or very bright light) to flower well; shade gives leaves, not blooms.

How do I make big-flowered catmint bloom?

Give big-flowered catmint the sunniest spot you have — for most bedding and fruiting plants, more direct light directly means more flowers. Move off high-nitrogen feeds and use a higher-potassium "bloom" or tomato-type feed as it comes into flower.

When does big-flowered catmint normally bloom?