Growing geraniums in USDA Zone 8 means gardening with mild winters and a long growing season, with a last frost in early spring and a first frost in late autumn. The average last spring frost falls around Mar 1–15 and the average first autumn frost around Nov 15–Dec 1, with average winter lows of 10 to 20°F. Those are USDA/NOAA zone averages, not promises for any one garden — check your local extension service. Geraniums are a reliable choice in this zone, and this guide covers when to plant geraniums in Zone 8, with the soil, spacing, sun, water and care it needs. Use the Zone 8 planting calendar to see what else to sow alongside it.
Zone 8 at a glance
USDA Zone 8 has average winter lows of 10 to 20°F, a last frost around Mar 1–15 and a first frost around Nov 15–Dec 1. Plan around those averages, not the calendar: a cold spring or a warm autumn can shift everything by a week or two, so check your local extension service for your area. Geraniums are tender to cold, so time planting around the frost dates first and everything else second.
| 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 | Start indoors; seed is slow, so begin early |
| Transplanting | Mid-March, after the average last frost (Mar 1–15) |
| Harvest | Flowers from late spring through autumn, 70–90 days after sowing |
| Sun | full sun |
| Soil pH | 6.0–7.0 |
| Spacing | 12–18 inches |
| Water needs | moderate |
When to plant geraniums in Zone 8
January to February, about 8–10 weeks before the average last frost. Seeds germinate in 7–14 days, and the crop takes 70–90 days to maturity, so work the dates back from the frost averages: flowers from late spring through autumn, 70–90 days after sowing. If you are unsure of your own dates, the seed-starting calculator will work the timing out from your last frost. Frost dates are zone averages — check your local extension service before you commit to a date.
Starting geraniums in Zone 8
Geraniums (pelargoniums) are started indoors in January to February, about 8–10 weeks before the average last frost — seed is slow to germinate (7–14 days) and seedlings grow slowly, so start early and give them strong light. Most gardeners buy young plants in spring, which is simpler. Set plants out in mid-March, after the average last frost (Mar 1–15), and handle seedlings gently — their stems break easily.
Soil, spacing, sun and water
Geraniums want full sun and well-drained soil with a pH of 6.0–7.0. They are excellent in containers, where drainage is easy to control, and they dislike wet feet more than anything. Space plants 12–18 inches apart in beds, use a free-draining potting mix in pots, and do not overwater — let the surface dry between waterings. Space plants 12–18 inches apart — it is tempting to crowd plants in, but crowded plants stay small and invite disease, so measure the bed out before you plant. Geraniums need moderate 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 geraniums include lavender, marigolds, garlic, chives. The companion planting finder can suggest combinations for your whole bed. Related reading: Dahlias. Avoid planting geraniums where the same family (Geraniaceae) grew last year.
Pests and problems
The common pests and problems to watch for with geraniums are aphids, slugs, cutworms. Inspect plants regularly, especially the undersides of leaves, and act early: hand-pick larger pests, wash aphids off with a strong jet of water, and remove badly affected leaves rather than waiting for the problem to spread. Geraniums are relatively trouble-free. Aphids can appear on buds — wash them off with water — and slugs may damage young plants. Whiteflies can be a problem on plants kept indoors over winter; check the undersides of leaves and wash plants before bringing them inside.
Harvest and storage
Geraniums flower from late spring through autumn, 70–90 days after sowing, and deadheading spent blooms keeps them flowering for months. Cut stems for small posies in the morning. In Zone 8, geraniums are tender and will be killed by a hard frost, so take cuttings in autumn or bring pots indoors before the first frost (Nov 15–Dec 1) to overwinter them.
Making the most of Zone 8
Zone 8 gives geraniums a long season from March to November, but they are tender — the first frost ends them. Treat them as a long summer display, take cuttings in autumn, and you will have free plants again next spring. Keep a simple notebook of what you sowed, when it went out, and when it flowered or fruited — after one season you will have a record far more useful to your own garden than any general guide.
Related Zone 8 guides in this series: March in Zone 8 and Geraniums in Zone 1.
Frequently asked questions
When should I plant geraniums in Zone 8?
Work back from the average last frost around Mar 1–15: start indoors; seed is slow, so begin early. Check your local extension service — these are zone averages, not exact dates for your garden.
How long do geraniums take to grow in Zone 8?
Seeds germinate in 7–14 days, and the crop takes 70–90 days to maturity. In Zone 8, cool soil can slow growth early in the season, so allow the longer end of the range.
Can geraniums survive winter outdoors in Zone 8?
Usually not — geraniums are tender and a hard frost will kill them, even though Zone 8 winters are mild (lows of 10 to 20°F). Overwinter them indoors or take cuttings in autumn. Check your local extension service for the first frost date in your area.
What soil and spacing do geraniums need in Zone 8?
Geraniums need full sun and soil pH 6.0–7.0, spaced 12–18 inches apart. Dig in well-rotted compost, water deeply, mulch, and test your soil through your local extension service.