The Fast-Growing Perennial Flower You Can Plant In Spring For Its Beauty

Spring has a way of making the garden feel full of promise, and late March is exactly the right moment to act on it. If you're looking for a flowering perennial that establishes quickly, returns reliably year after year, and delivers a visual impact that carries through the warmest months, catmint (Nepeta) deserves a serious place in your planting plan. It grows with an urgency that few perennials match, producing soft lavender-blue flower spikes within weeks of going in the ground, all while asking very little in return.

This article walks you through everything you need to plant catmint successfully this spring — from choosing the right variety and preparing your soil, to spacing, aftercare, and the single pruning trick that doubles your flowering season. The ground is still cool but workable, conditions are ideal, and by early summer you'll have a plant already putting on a show.

Why Catmint Is the Perennial Worth Planting This Spring

Catmint belongs to the Lamiaceae family — the same group as lavender and salvia — and it shares their reputation for toughness and aromatic foliage. Unlike many flowering perennials that take two or three seasons to hit their stride, catmint begins performing in its first year. A well-sited plant planted in late March can be flowering by late May, with clouds of small tubular blossoms in shades ranging from pale lilac to deep violet, depending on the variety.

The foliage itself earns its keep. Soft, grey-green leaves with a faintly minty scent form a mounding habit that suppresses weeds naturally and holds its shape through the season. Bees, bumblebees, and butterflies find catmint irresistible, making it one of the most reliable pollinator plants you can grow. It also tolerates drought once established — a significant advantage as summer dry spells become more frequent.

Choosing the Right Variety

Nepeta × faassenii 'Walker's Low' is the benchmark: it grows to around 60–90 cm (24–36 in) in height and spread, produces rich violet-blue spikes from May to August, and repeats reliably after cutting back. It won the Perennial Plant Association's Plant of the Year award and remains the most widely grown selection for good reason.

For smaller spaces or border edges, 'Kit Cat' and 'Junior Walker' stay compact at 30–40 cm (12–16 in), offering the same flower quality in a tidier footprint. For something bolder, Nepeta 'Six Hills Giant' reaches 90–120 cm (36–48 in) and creates a substantial structural presence at the back of a mixed border. All three establish quickly from pot-grown specimens planted in spring.

What You Will Need

Materials and supplies

• 1–3 pot-grown Nepeta plants per linear metre of planting (depending on variety size)
• Garden compost or well-rotted manure (1–2 bucketfuls per planting hole)
• Horticultural grit — one handful per planting hole on heavy clay soils
• Slow-release granular fertiliser (balanced NPK, optional)
• Mulch — bark, gravel, or composted wood chip, applied at 5–7 cm (2–3 in) depth
• Water — at least 5–10 litres per plant at planting time

Tools

• Garden spade or border spade
• Hand trowel
• Garden fork (for breaking up compacted subsoil)
• Watering can or garden hose with a gentle rose attachment
• Sharp garden shears or secateurs (for the post-flowering cut)
• Kneeling pad

Step-by-Step Planting Guide

1. Choose the right site

Catmint performs best in full sun to partial shade, with at least five to six hours of direct light per day. It tolerates a wide range of soils but absolutely requires good drainage — waterlogged roots over winter are the main cause of plant loss. Avoid low-lying spots where water sits after heavy rain. A south- or west-facing border, a raised bed, or a gravel garden are all ideal situations. Proximity to a path or seating area is worth considering: brushing against the foliage releases a pleasant aromatic scent that earns its keep throughout the season.

2. Prepare the soil

Dig the planting area to roughly one spade's depth (25–30 cm / 10–12 in), breaking up any compaction with a fork. If your soil is heavy clay, work in a generous handful of horticultural grit per planting hole to improve drainage — catmint will tolerate lean, poor soils far more readily than wet, airless ones. On sandy or chalky soils, incorporate a bucketful of garden compost to help retain some moisture during the establishment phase. Rake the surface level and remove any perennial weed roots you encounter — once catmint spreads, weeding becomes harder.

3. Soak the rootball before planting

Before lifting the plant from its pot, submerge the rootball in a bucket of water for 15–20 minutes until air bubbles stop rising. This step is straightforward but frequently skipped, and it makes a measurable difference to how quickly a plant establishes. A rootball that goes into the ground already saturated experiences far less transplant stress, particularly during the drier spells that often follow a mild March.

4. Dig and position the planting hole

Dig a hole roughly twice the width of the rootball and equal in depth. Catmint should sit at the same level as it was growing in the pot — the crown (the point where stems meet roots) should be at soil level, neither buried nor raised proud of the surface. Place the plant in the hole and check the depth before backfilling. The rootball should feel snug, with no air pockets between it and the surrounding soil.

5. Backfill and firm in

Return the excavated soil, incorporating a light handful of slow-release granular fertiliser if desired. Firm the soil gently but decisively around the rootball using the heel of your boot or your hands — the aim is to eliminate air pockets without compacting the soil so hard that drainage is impaired. You should feel the plant resist slightly when tugged: that resistance indicates good contact between roots and soil. Water in immediately with a full watering can, allowing the water to drain fully before moving to the next plant.

6. Space plants correctly

For Walker's Low and similarly sized varieties, allow 45–60 cm (18–24 in) between plants. They will fill the gaps within one growing season, creating the dense, weed-suppressing carpet that makes catmint so valuable as a border filler. Resist the temptation to crowd them: plants given sufficient space establish faster, flower more freely, and are far less prone to the mildew that can affect congested growth in humid periods.

7. Mulch the planting area

Apply a 5–7 cm (2–3 in) layer of mulch across the planting area immediately after watering. Keep mulch clear of the plant crowns by a few centimetres to prevent rot. Gravel or grit mulch suits catmint particularly well — it reinforces the free-draining conditions the plant prefers and reflects heat upward through the foliage, slightly extending the season. Bark mulch works equally well on moisture-retentive soils and is more effective at suppressing weeds.

The Professional's Tip

The single most effective technique with catmint is the Chelsea chop: cutting plants back by roughly one-third to one-half in late May, just before the main flush of flower buds opens. The cut delays flowering by two to three weeks but produces a far more compact, self-supporting plant that doesn't sprawl — and the second flush, which arrives in mid to late summer, is often denser than the first. For an even longer display, cut only half the plants in a group in late May and allow the others to flower on their normal schedule. You'll have continuous colour from late May through to September. In a late spring like this one, with March temperatures still variable, the Chelsea chop also gives newly planted specimens an extra few weeks to root in before flowering demands kick in.

Aftercare and Long-Term Maintenance

Water newly planted catmint regularly during its first six to eight weeks, particularly during dry spells — once or twice a week in the absence of rain, directing water at the base of the plant rather than over the foliage. After the first season, established plants require almost no supplementary watering except during prolonged drought. Feed lightly with a balanced fertiliser in early spring each year; avoid high-nitrogen feeds, which promote leafy growth at the expense of flowers.

Cut plants back to within 10–15 cm (4–6 in) of the ground in autumn or early spring, removing the old woody stems. In very cold regions, leaving the old stems over winter provides a small degree of crown insulation and can be cleared in March. Divide large clumps every four to five years in spring to maintain vigour — lift the crown with a fork, split it into sections with two healthy growing points each, and replant immediately.

Going Further: Combinations and Design Uses

Catmint is one of the most versatile plants in the border palette. Its soft lavender-blue sits naturally alongside the warm tones of Achillea 'Terracotta', the deep burgundy of Knautia macedonica, and the silver foliage of Stachys byzantina. At border edges, it softens hard paving lines and spills attractively over gravel paths. In a cutting garden, the flower spikes are short-lived in a vase but worth including in informal arrangements.

No planning permission or regulatory approval is required for planting perennials in a private garden. If you are gardening in a rental property or a managed development, check your tenancy agreement or leasehold terms before making permanent planting changes to shared or communal areas.

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Frequently Asked Questions