Nepeta nervosa 'Blue Moon'

Nepeta nervosa 'Blue Moon' - compact catmint with deep blue-violet spikes and a tidy habit

Nepeta nervosa 'Blue Moon' is a reliable perennial for long flowering without constant fuss. It forms a mound of aromatic leaves, then throws flower spikes for weeks. Sun keeps the plant tighter and helps prevent floppy growth. After the first flowering peak, a cut back refreshes the clump and often triggers a second flush. In very rich soil, stems can splay, so leaner ground keeps the habit neater.

It’s also forgiving: sun, free drainage, and a sensible watering rhythm in the first season are enough for a long-lived clump. Once rooted in, it handles dry spells. Repeated drought stress is what usually makes clumps look uneven later in the season.

Size and structure

This cultivar is valued for staying compact. In most gardens it forms a rounded mound. A wide sprawl, which makes it easier to place in tighter planting schemes and gravel edges often results in patchy growth.

• Mature size: typically around 30 to 40 cm tall and roughly the same spread.
• Habit: bushy mound; flower spikes held above the foliage.
• Scent: foliage releases a herbal fragrance when touched.

Light and soil

Full sun is the sweet spot: sturdier stems, stronger flowering, and tighter growth. Light shade is tolerated, but shade usually means fewer flowers and looser form.

Soil can be sandy, loamy, or chalky as long as it drains freely. If the ground is heavy, improve the structure or plant slightly raised so the crown isn’t sitting in cold, saturated soil.

Watering: early attention, then a lighter touch

Water deeply at planting and keep moisture steady for the first weeks. After that, let the surface dry between waterings. Once established, 'Blue Moon' copes with drought well, but containers and very light soils still dry quickly in heat and wind.

If growth looks lush but floppy, it’s usually too much water or too much fertility. A lack of support can undo the benefits of good drainage and light.

Tidy-up and cut-back

After the first flush of flowers, a light shear keeps the mound compact and often encourages a second bloom later in summer. In late winter or early spring, cut back old stems to make way for fresh shoots.

Where it struggles

The most common disappointments come from low light and slow-draining soil. In shade it stretches; in persistently wet ground it weakens and can thin out over winter.

Using three plants well

Repeat is where this catmint looks best. Plant the set as a small drift for a calm ribbon of colour, or split it between a border edge, a gravel bed, and a sunny pot to echo the same tone in different places.

Sold as three plants for quick coverage and an instant, balanced look.

How 'Blue Moon' differs from sprawling catmints

'Blue Moon' stays shorter and upright at maturity. That makes it easier to use in tighter beds, along narrow paths, or in pots where a plant that “leans out” quickly becomes awkward.

The flower spikes are also relatively short and dense, so the colour reads as a concentrated band. A loose haze often results in patchy growth.

Spacing and layout

Because it stays compact, it holds up well planted closer together than larger catmints. Spacing around 30 to 40 cm gives a fuller line without crowding, especially if you shear lightly after the first flush.

For distinct individual mounds, give it a little more room. Overfeeding, which can make the shape blur commonly shows up later as stalled growth and dieback.

• Border edge: repeat in a line for a calm ribbon of colour.
• Gravel bed: use as a low, scented layer between stones and larger perennials.
• Pots: plant one per container as a neat, long-flowering top layer.

Water, heat, and keeping flowering going

Once established, this catmint handles dry conditions well, but extreme heat and wind can shorten the flower show if the root zone dries completely. Deep watering during prolonged drought is the best support; small daily splashes don’t help much and often just encourage shallow roots.

In very hot positions, a little afternoon shade can protect foliage from looking scorched, but keep overall light levels high so stems don’t stretch.

Cut-back options: a light tidy, or a harder reset

After the first flush, a light shear (just above the foliage mound) keeps the plant compact and often triggers a second set of flower spikes. If a plant looks tired or ragged, a harder cut-back is still safe - new shoots usually come quickly from the crown in warm weather.

In late winter or early spring, cut back old stems so new growth starts clean. Leaving some structure through winter can help protect the crown in exposed gardens.

Soil and feeding (keep it simple)

Moderate fertility is enough. If growth turns lush and floppy, reduce feeding and check drainage. Catmints generally flower better and keep a tighter outline when the soil isn’t overly rich.

On very sandy soils, a small amount of organic matter in the planting zone helps hold enough moisture through summer without turning the root zone soggy.

Division and longevity

Compact catmints can live for years, but clumps sometimes thin in the centre after repeated seasons. Lifting and dividing the outer, vigorous sections every few years is the simple way to keep plants dense and flowering heavily.

Division is best done when growth is active but not stressed - cool, damp weather helps plants re-root quickly.

Common issues and what they usually mean

Poor flowering is almost always a light issue. If the plant sits under taller neighbours or in part shade, it will still grow but the flower show will thin out.

Soft, leaning stems usually point to soil that is too rich or too wet. Improve drainage and shear back so the next growth comes in sturdier.

Using a set of three plants

Three plants give you enough material for a deliberate repeat. Plant them as a small drift for a calm ‘blue pocket’, or run them as a short line along a path where the scented foliage gets brushed as you pass.

They also split well: one for a pot, one for a border edge, and one for a gravel bed - same colour, different textures.

Container notes

In pots, choose a container that won’t overheat too fast and a mix that drains freely. Water deeply, let the surface dry, and shear after flowering to keep the plant compact. A pot also helps if garden soil is heavy and slow to drain.

Most perennial disappointments come down to root oxygen, drainage, and moisture balance. Spring performance is weakest where the root zone stays wet and tight, especially in pots that do not drain freely, and flowering can be shorter.