If you’re planning to add catnip to your garden, one of the first questions you’ll have is how tall does catnip grow. Understanding the maximum height of catnip helps you plan where to plant it so it doesn’t overshadow smaller herbs.
Most common catnip (Nepeta cataria) typically reaches between 2 and 3 feet tall at maturity. However, under perfect conditions, it can get even taller. Let’s look at what influences its size and how you can manage it for a healthy, attractive plant.
How Tall Does Catnip Grow – Maximum Height of Catnip
The maximum height of catnip is generally around 3 feet, but it’s not uncommon for well-established plants in rich soil to hit 3.5 or even 4 feet in a single season. This height includes the flower spikes, which add significant length to the stems. The plant tends to have a bushy, sprawling habit, often growing just as wide as it is tall.
Factors That Influence Catnip Height
Several key factors determine whether your catnip stays at a modest 2 feet or stretches toward its maximum potential. By controlling these, you can somewhat influence the final size.
1. Sunlight Exposure
Catnip thrives in full sun, meaning at least 6 to 8 hours of direct light daily. Plants in full sun grow more compact and sturdy, but they can also reach their full height potential. In partial shade, catnip will become leggy as it stretches for light, often resulting in weaker, taller stems that flop over.
2. Soil Quality and Nutrients
Catnip prefers moderately fertile, well-draining soil. Surprisingly, soil that is too rich in nitrogen can cause rapid, lush growth, leading to very tall plants that may require staking. Leaner soil often produces a more manageable, though still healthy, plant.
3. Watering Practices
While drought-tolerant once established, consistent moisture supports steady growth. Overwatering can lead to root issues, but underwatering will definately stunt the plant, keeping it shorter and less vigorous.
4. Climate and Growing Zone
Catnip is perennial in USDA zones 3-9. In warmer climates with longer growing seasons, the plant has more time to grow taller and may even produce multiple flushes of growth if cut back.
Popular Catnip Varieties and Their Heights
Not all catnip is created equal. ‘Nepeta cataria’ is the standard, but other cultivars and related species offer different sizes.
- Common Catnip (Nepeta cataria): The classic. Reaches 2-3 feet, with a maximum of about 4 feet.
- ‘Citriodora’ (Lemon Catnip): Similar in height to common catnip but with a lemony scent.
- Catmint (Nepeta mussinii/faassenii): Often confused with catnip, these are usually shorter, neater, and more ornamental, typically staying under 1-2 feet tall.
- ‘Six Hills Giant’ Catmint: A larger cultivar that can form a big mound up to 3 feet tall and wide.
How to Manage and Control Catnip Height
If you want to keep your catnip from reaching its maximum height—perhaps to maintain garden order or encourage bushier growth—a few simple techniques work wonders.
Pruning and Pinching
This is the most effective method. Early in the growing season, when the plant is about 6-8 inches tall, pinch or snip off the top set of leaves. This encourages the plant to branch out, creating a denser, bushier form that may actually be wider than it is tall.
- Use clean, sharp scissors or pruning shears.
- Pinch just above a set of leaves.
- You can repeat this once or twice in early summer.
Strategic Harvesting
Harvesting leaves for your cat is a form of pruning. Regularly snipping stems throughout the season, especially before flowers form, promotes new growth and controls height. Always harvest from the top down.
Controlling Fertilizer
Avoid high-nitrogen fertilizers. A top dressing of compost in spring is usually sufficent for the entire growing season. Too much feed leads to excessive, soft growth.
Providing Support
If your catnip does reach its maximum height and begins to flop, use simple grow-through plant supports or small stakes. Install them early in the season so the plant grows through them and hides the support.
Common Problems Related to Height
Tall catnip can present a couple of issues. Being prepared makes them easy to solve.
- Flopping Over: The number one problem. Caused by too much shade, rich soil, or heavy rain on tall growth. The solution is prevention through pruning, staking, or planting in full sun.
- Self-Seeding: Tall flower spikes produce many seeds. If you don’t want catnip spreading, deadhead the flowers before they go to seed.
- Blocking Sun: A 4-foot tall, bushy plant can shade out smaller sun-loving herbs planted too close. Give catnip plenty of space, at least 18-24 inches from it’s neighbors.
Step-by-Step Guide to Growing Tall, Healthy Catnip
- Choose the Right Spot: Select a location with full sun and well-draining soil.
- Plant at the Right Time: Sow seeds or transplant seedlings after the last frost. Space plants 18-24 inches apart.
- Water Wisely: Water regularly until established. After that, water only during prolonged dry spells.
- Prune Early: Pinch back young plants to encourage bushiness.
- Manage Flowers: Decide if you want to allow flowering (attracts bees!) or deadhead to prevent self-seeding and promote more leaves.
- Cut Back in Fall: After the first hard frost, cut stems down to a few inches above the ground.
FAQ About Catnip Growth
How fast does catnip grow?
Catnip grows relatively quickly. From seed, it can reach 12-18 inches within the first growing season. Established plants will shoot up to their full height each spring.
Does catnip grow back every year?
Yes, catnip is a hardy perennial. It dies back to the ground in winter and regrows from its root system each spring, often coming back larger each year.
Can catnip grow in pots?
Absolutely. Container growth will naturally limit its size. Use a pot at least 12 inches deep and wide. Potted plants may not reach the same maximum height as those in the ground, which is often a benefit.
What is the diffrence between catnip and catmint?
While both are in the Nepeta family, common catnip (Nepeta cataria) is the one cats go crazy for and tends to grow taller and more sprawly. Catmints (like Nepeta faassenii) are often more compact and are primarily used as ornamental border plants.
Should I let my catnip flower?
Flowering is fine! The bees and pollinators love the blooms. Just know that the plant will put more energy into flowers and seeds once it blooms, and leaf production may slow. The flower spikes also add to the overall height.
Knowing how tall catnip grows helps you integrate this fun and useful herb into your garden design successfully. With a little management, you can enjoy its benefits—from entertaining your feline friends to attracting pollinators—without it taking over. Remember, a quick pinch in spring is the secret to a bushier, more controlled plant that still provides plenty of leaves for harvest.