How to Grow Catnip Plants

Catnip (Nepeta cataria) is a herbaceous perennial that thrives in much of North America and is very easy to grow. It has a clump-forming growth habit with square stems and triangular to oval, gray-green leaves with toothed edges that stretch around 3 inches long. Flower spikes appear in the late spring to early fall, bearing clusters of small blooms that are white with light purple markings.

The catnip plant is a fast and aggressive grower and can quickly spread throughout the landscape if not kept in check. It is considered invasive in a couple of spots in the United States, such as West Virginia and Maryland. It will reach its mature size in a single season and should be planted in the spring. Note that, while many cats enjoy catnip, the oils of the plant are technically toxic to them.

How to Plant Catnip

When to Plant

Plant catnip in the spring after the threat of frost has passed in your area. Start catnip seeds indoors around six weeks prior to your projected last frost date.

Selecting a Planting Site

The ideal garden location for catnip will get lots of sunlight and have well-drained soil. Make sure no taller plants nearby are creating too much shade for the catnip throughout the day. However, if you live in a hot climate, catnip will appreciate some afternoon shade. Catnip also grows well in containers. In fact, a planting site with some kind of boundary, such as a pot, raised garden bed, or stone wall will help to contain catnip's spread. You can also grow an indoor catnip plant. All you need is a sunny sill with direct light.

Spacing, Depth, and Support

Space catnip plants 18 to 24 inches apart in the garden. Position nursery plants and seedlings at the same depth they were in their previous container. Lightly cover seeds with soil. A support structure is typically not necessary for catnip.

Catnip Plant Care

Light

Catnip prefers full sun, meaning at least six hours of direct sunlight on most days. Too little light can cause leggy growth with sparse foliage. However, catnip does struggle in extreme heat. So if you live in a hot climate, give your catnip a little shade from the strong afternoon sun.

Soil

These plants aren’t fussy about their soil as long as they have good drainage. They can tolerate poor, rocky, and dry soils. A well-draining sandy or loamy soil is best with a slightly acidic to slightly alkaline soil pH (6.1 to 7.8).

Water

Catnip is a very drought-tolerant plant, and sitting in waterlogged soil can kill it. Keep the soil of seedlings lightly moist but not soggy. Mature plants likely won’t need watering unless you have a prolonged period of drought. If the foliage is wilting, give your catnip a deep watering.

Temperature and Humidity

Catnip prefers temperatures between 55 and 85 degrees Fahrenheit. The plant tends to struggle in hot, humid climates. Especially in high humidity, make sure there is good air circulation around the plant to help prevent fungal growth. 

Fertilizer

Mix some compost into the soil at the time of planting to give your catnip a boost. After that, catnip typically won’t need additional feeding. But if you have very poor soil, you can use an all-purpose liquid plant food (for the amount to use, follow product label instructions) or a layer of compost each spring.

Pollination

Catnip is a self-pollinating plant. It will attract bees and other pollinators to the garden.

Types of Catnip

Besides Nepeta cataria, there are several plants that go by the name catnip, including: 

• Nepeta citriodora: Known as lemon catnip, this plant grows slightly smaller than Nepeta cataria and has a lemony fragrance.
• Nepeta camphorata: Commonly referred to as camphor catnip, this plant remains under 2 feet tall and wide.
• Nepeta parnassica: Known as Greek catnip, this plant also remains smaller than 2 feet tall and wide and bears light pink flowers.
  

Catnip vs. Catmint

The catnip plant Nepeta cataria is commonly confused with the catmint plant Nepeta mussinii. Both plants have gray-green foliage on square stems. However, catmint has a longer blooming period. And its flowers are purple while catnip’s are primarily white. Moreover, catnip is the plant that attracts cats while catmint does not. Catmint also generally has a nicer form, making it better for landscaping and ground covering purposes. 

Harvesting Catnip

Harvest catnip when it’s in bloom. Late morning is a good time to harvest after the dew has dried but before the day heats up and potentially causes the plant to wilt. Cut off entire stems or even the whole plant if you wish. Catnip plants are good for making actual catnip for your cat's enjoyment. Catnip is used dried in sachets, teas, cat toys, and more. Hang the stems upside-down for drying in a dark, dry, well-ventilated space as soon as possible after harvesting. Once they’ve dried out, which usually takes two to three weeks, the leaves and flowers can be crumbled for use.

How to Grow Catnip in Pots

Growing catnip in a pot is a good option because it will prevent the plant from spreading into unwanted places. Use a container that’s at least 12 inches in diameter, and make sure it has a drainage hole. An unglazed clay container is ideal because it will allow excess soil moisture to escape through its walls. Use a well-draining potting mix, and plant your catnip at the same depth it was in its previous container. 

Pruning

Pruning catnip is primarily to limit its spread and tidy up its growth. To minimize its spread, prune off the flowers as they’re starting to degrade and before they go to seed. This also can encourage further blooming. Also, cut down new sprouts from underground runners as they appear if you don’t want the plant to spread. Furthermore, pinch back the stems on young plants to encourage bushier growth. And after the first frost in the fall, cut back mature plants to just a few inches from the soil. They will regenerate in the spring with fresh growth.

Propagating Catnip

Catnip will readily spread on its own. But it’s also easy to propagate the plant via cuttings. Not only is this an inexpensive way to get a new plant, but cutting back the stems can also promote bushier growth on the parent plant. The best time to take cuttings is in the spring or early summer. Here’s how:

1. With sterile shears, cut off a 4- to 6-inch piece of stem at a 45-degree angle just below a leaf node.
2. Remove the leaves on the lower half of the cutting. 
3. Place the cutting either in a small container of water or moist soilless potting mix. A healthy root system will typically form in either scenario. Put the container in a warm spot with bright, indirect light.
4. Change the container water each day, or continue to keep the potting mix moist. 
5. Roots should appear within a week. Once the plant has produced new foliage growth, it’s ready to be transplanted. 

Mature catnip also can be propagated via division. This is a great way to reinvigorate an overgrown plant. Here’s how:

1. Dig up the plant, aiming to keep its roots as intact as possible.
2. Use sterile shears or a sharp spade to divide the clump in half. 
3. Replant the separate clumps at the same depth they were previously growing.

How to Grow Catnip From Seed

Start catnip seeds indoors about six weeks prior to your projected last frost date in the spring. First, place them in a freezer overnight, and then soak them in water for 24 hours. This stratification process can encourage germination. Then, plant the seeds about 1/8 inch deep in a tray filled with moistened seed-starting mix. Place the tray in a warm, bright spot. Continue to keep the soil moist, and germination should occur within two weeks. Plant the seedlings outside after frost is out of the forecast.

Potting and Repotting Catnip

Potted catnip plants will generally need more water and food than those grown in the ground. However, make sure the container does not become waterlogged. Plan to repot your catnip when you see roots growing out of the drainage holes and popping up above the soil line. Choose one container size up, and replant with fresh potting mix. Even if your plant doesn’t need a larger container, it’s ideal to refresh it with new potting mix every couple of years. 

Overwintering

Catnip typically does fine over the winter within its growing zones. Cut back any tender new growth in the fall, so cold weather doesn’t damage it and weaken the plant. And be sure to stop fertilizing in the fall to avoid promoting new growth. Don’t water the plant over winter. Wet soil in the wintertime can be fatal.

Common Pests and Plant Diseases

Catnip isn’t prone to many pests or disease issues. If the plant sits in waterlogged soil for too long, it can succumb to rot. Another concern is the plant attracting cats, who will try to rub and roll on the foliage and potentially damage the stems. Placing some garden fencing or stakes around the plant can help to prevent this, as can growing the catnip in a container.