Rosemary is the woody Mediterranean shrub that turns a sunny corner into a fragrant, evergreen feature — and in Zone 8 it is a true perennial, living for years where colder zones must treat it as an annual. The secret is drainage: rosemary would rather be dry than wet, and it dies faster from soggy soil than from cold. This guide covers when to plant rosemary in Zone 8 and how to give it the sunny, sharp-drained home it wants.
Zone 8 at a glance
Zone 8 covers parts of the southern United States, the Pacific Northwest coast and parts of California, where average winter lows run 10 to 20°F. The average last spring frost falls Mar 1–15 and the average first autumn frost Nov 15–Dec 1. Those are USDA zone averages drawn from NOAA frost records, not exact dates for any one garden — frost dates vary by microclimate, elevation and year, so always check your local extension service and the forecast before planting. Use the frost date calculator for your own averages, and browse the planting calendar hub for the full Zone 8 year.
When to plant rosemary in Zone 8
| Step | Timing in Zone 8 |
|---|---|
| Start indoors | February to March, from seed or cuttings |
| Transplant outdoors | April to May, after the last frost |
| Plant from pots | April to May, or September |
| Prune lightly | After flowering, or in spring |
| Harvest | Year-round once established; 90–120 days to maturity |
Rosemary is listed as tender, so young plants go out after the average last frost of Mar 1–15 — the Zone 8 April guide is the main planting window. Once established, rosemary is a perennial in Zone 8 and survives the mild winters, with lows of 10 to 20°F, especially in a sheltered, sunny spot with sharp drainage. Use the seed starting calculator to work out dates for your own garden.
How to start rosemary
Rosemary is slow from seed — germination takes 14–28 days — so most gardeners start with cuttings or a bought plant. Take cuttings in spring from new growth, strip the lower leaves, and root them in gritty compost. If sowing seed, start indoors in February to March on a warm windowsill. Harden plants off for a week before planting out in April to May, spacing them 24–36 inches apart — this is a shrub, and it will fill the space.
Soil, spacing and sun
Rosemary demands full sun and sharp drainage. It prefers poor, gritty, even slightly alkaline soil and a pH of 6.0–7.0, and it hates rich, wet ground. On clay, plant in a raised bed or a large pot with grit mixed into the compost, and never let it sit in water. Space plants 24–36 inches apart. Do not feed it heavily — lean soil gives the most fragrant leaves.
| Fact | Range |
|---|---|
| Sun | full sun |
| Days to germination | 14–28 |
| Days to maturity | 90–120 |
| Spacing | 24–36 in |
| Soil pH | 6.0–7.0 |
| Sowing method | start indoors |
| Cold tolerance | tender |
All figures are broad published ranges from standard horticultural references, and they vary by variety, soil and weather. Check your local extension service for advice on your own garden.
Watering and feeding
Water needs are low: water young plants until established, then water sparingly. Overwatering is the commonest cause of rosemary death in Zone 8, especially in winter when wet soil plus cold rots the roots. Water at the base in dry spells, let the soil dry between waterings, and never water in cold, wet weather. In pots, make sure the container drains freely and empty the saucer.
Companion planting
Tomatoes, peppers, marigolds and cabbage are listed companions, and rosemary is a valued neighbour in the vegetable garden: its scent is said to confuse carrot rust fly and cabbage pests. Plant it at the edge of the vegetable bed or in a pot nearby, where it can grow into a shrub without shading smaller crops. The companions listed for rosemary in standard references are tomatoes, peppers, marigolds, cabbage.
Pests and problems
Aphids, spider mites and whiteflies are the listed pests, but rosemary's real enemy is root rot from wet soil. Keep the soil free-draining, space plants for airflow, and avoid wetting the foliage. Spider mites appear in hot, dry conditions — a strong jet of water on the foliage helps. Prune out any dead wood in spring. The pests most often listed for rosemary are aphids, spider mites, whiteflies. Inspect plants weekly, act early while numbers are small, and encourage natural predators such as ladybirds and hoverflies.
Harvest and storage
Once established, harvest year-round: snip sprigs as needed, cutting just above a leaf joint, and never take more than a third of the plant at once. The flavour is strongest just before flowering. Rosemary dries well — hang sprigs in a dry, airy place — and the leaves freeze well too. Prune lightly after flowering to keep the plant compact, and cut out dead wood in spring. A well-placed rosemary can live for many years in Zone 8.
Frequently asked questions
When should I plant rosemary in Zone 8?
Transplant young plants outdoors in April to May, after the average last frost of Mar 1–15. You can also plant pot-grown rosemary in September. Once established it is a perennial in Zone 8.
Why did my rosemary die over winter?
Almost always wet soil, not cold. Rosemary survives Zone 8 winters of 10 to 20°F if the soil drains sharply. On clay or in a wet spot, grow it in a raised bed or a pot and keep it out of winter wet.
Should I grow rosemary from seed?
Seed is slow and unreliable — germination takes 14–28 days. Cuttings or a bought plant are faster and give you a known variety. Take cuttings in spring from new growth.
How do I prune rosemary?
Prune lightly after flowering and in spring, cutting back into green growth but never into old brown wood, which does not regrow. Never take more than a third of the plant at once.
For the full year, browse the planting calendar hub. Compare with Rosemary in Zone 7, and see also Thyme in Zone 8.