Catnip is a hardy, mint-family herb famous for the effect its leaves have on cats — most cats roll, rub and purr in it — but it is also a useful garden plant in its own right. It makes a soothing tea, attracts pollinators with its small white flowers, and its strong scent is said to deter some garden pests. In USDA Zone 8 it grows as a tough perennial that shrugs off heat, drought and poor soil, and comes back year after year. This guide covers when to plant catnip zone 8, and what soil, spacing, sun, water and care it needs.
Zone 8 at a glance
Zone 8 has average winter lows of 10 to 20°F, an average last spring frost of Mar 1–15 and an average first autumn frost of Nov 15–Dec 1 — roughly 240–270 frost-free days in an average year. Frost dates are averages and ranges, not exact dates for any specific place: they vary by microclimate, elevation and year, so check your local extension service.
| Detail | Zone 8 guidance |
|---|---|
| Average last spring frost | Mar 1–15 (average/range) |
| Average first autumn frost | Nov 15–Dec 1 (average/range) |
| Days to germination | 7–14 days |
| Days to maturity | 70–90 days |
| Sowing | both |
| Sun | full sun |
| Soil pH | 6.0–7.0 |
| Spacing | 12–18 inches |
| Water needs | low |
When to plant catnip in Zone 8
Sow catnip outdoors from early March, around the average last frost (Mar 1–15), or start it indoors 6–8 weeks earlier and transplant out after mid-March. Catnip is hardy, so seedlings tolerate a light frost, and Zone 8's long season gives it months to establish. You can also sow a second batch in early autumn, around September, for plants that overwinter and grow strongly the following spring. With 70–90 days to maturity, a March sowing is ready for a first harvest by early summer, and established plants produce from spring until the first frost in mid-November. The Zone 8 March guide covers the same planting window.
Work back from the frost dates rather than from a calendar date: the planting calendar hub gives the Zone 8 picture month by month, and the frost date calculator turns your frost averages into sowing dates. Frost dates are zone averages, so keep row cover or a frost cloth ready from the day you plant, and check your local extension service for the dates that apply to your county.
Starting catnip in Zone 8
Catnip seed germinates in 7–14 days, but it germinates best after a short chill — mix the seed with damp sand and refrigerate it for a week before sowing, or simply sow outdoors in March and let the cool soil do the work. Sow on the surface and press in lightly, as the seed needs light to germinate. Thin seedlings to 12–18 inches apart. The most important decision is where to plant it: catnip spreads by seed and by creeping stems, and like other mints it can take over a bed. Many Zone 8 gardeners grow it in a pot, or in a corner where it has room to roam. Harden indoor-started plants off for a week before transplanting.
Soil, spacing, sun and water
Give catnip full sun and light, well-drained soil — it thrives in poor, sandy soil and actually produces stronger-scented leaves when it is not overfed. It prefers a pH of 6.0–7.0. Water needs are low: water while plants establish, then water only in long dry spells. Overwatering and rich soil produce soft, floppy growth with weaker scent, so neglect suits catnip better than pampering. A gravel mulch keeps the crown dry and discourages rot in Zone 8's humid summers.
Full sun is the light requirement, in soil with a pH of 6.0–7.0. Test your soil through your local extension service, and dig in well-rotted compost before planting. Space plants 12–18 inches apart — crowded plants stay small and invite disease, so use the plant spacing calculator if you are laying out a bed. Catnip needs low water: water deeply and less often rather than lightly every day, water at the base in the morning so leaves dry before night, and mulch to keep the soil evenly moist. Check the soil a finger's depth down and water when it feels dry there.
Companion planting
Good companions for catnip include tomatoes, peppers, marigolds, cabbage. The companion planting finder can suggest combinations for your whole bed. Rotate crops each year and avoid planting where the same family (Lamiaceae) grew last year, to reduce soil-borne disease. A related Zone 8 guide is stevia — another herb that loves Zone 8's long, warm summers.
Pests and problems
The common pests and problems to watch for with catnip are aphids, spider mites, whiteflies. Aphids and whiteflies may gather on shoot tips, and spider mites can appear in hot, dry weather — a strong spray of water usually deals with them. The biggest pest is often the neighbourhood cats: they may roll on young plants and flatten them. Protect new plants with a wire cloche or a ring of twiggy sticks until they are established, and expect established plants to be visited regularly — that is half the point of growing catnip. Inspect plants regularly, especially leaf undersides, and act early: hand-pick larger pests and wash aphids off with water. A pest guide can help you confirm what you are seeing before you treat it.
Harvest and storage
Harvest catnip leaves and flowering tops from early summer onwards, cutting stems in the morning when the oils are strongest. Dry the stems in small bunches in a warm, airy place out of direct sun, then strip the leaves and store them in an airtight jar — dried catnip keeps its scent for months and is what most cats respond to best. For tea, use fresh or dried leaves. Leave some plants to flower for the bees, and cut the whole plant back by half in midsummer to encourage a fresh flush of growth before autumn. Established plants die back in winter and regrow from the crown in spring.
Frequently asked questions
When should I plant catnip in Zone 8?
Sow outdoors from early March, around the average last frost (Mar 1–15), or start indoors 6–8 weeks earlier. Autumn sowing in September also works for plants that overwinter.
Will catnip take over my garden?
It can — it self-seeds freely and spreads like other mints. Grow it in a pot, or in a contained corner, and deadhead before seed sets if you want to limit its spread.
Does catnip survive Zone 8 winters?
Yes, easily. It is hardy and perennial in Zone 8, dying back in winter and regrowing from the crown in spring, even after lows of 10 to 20°F.
How do I keep cats from destroying young catnip plants?
Protect seedlings with a wire cloche or twiggy sticks until the plants are bushy and established. Mature plants can handle a cat rolling in them, but seedlings get flattened.