Growing nasturtiums 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. Nasturtiums are a reliable choice in this zone, and this guide covers when to plant nasturtiums 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. Nasturtiums 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 | 50–60 days |
| Sowing | Direct sow after the last frost (mid-March to April) |
| Transplanting | Mid-March to April, after the average last frost (Mar 1–15) |
| Harvest | Flowers and leaves 50–60 days after sowing |
| Sun | full sun |
| Soil pH | 6.0–7.5 |
| Spacing | 8–12 inches |
| Water needs | moderate |
When to plant nasturtiums in Zone 8
Not needed; direct sow after frost. Seeds germinate in 7–14 days, and the crop takes 50–60 days to maturity, so work the dates back from the frost averages: flowers and leaves 50–60 days after sowing. If you are unsure of your own dates, the frost date 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 nasturtiums in Zone 8
Nasturtiums are direct-sown after the last frost (mid-March to April) in Zone 8 — they dislike transplanting, so sow where they will grow. Seeds germinate in 7–14 days; soaking them overnight before sowing can help them sprout faster. Space plants 8–12 inches apart, and give climbing types a fence or trellis, or let trailing types spill over a bed edge or container.
Soil, spacing, sun and water
Like cosmos, nasturtiums flower best in poor soil: rich soil gives leaves and few flowers, so do not fertilise them. Full sun and soil with a pH of 6.0–7.5 suit them, and they tolerate dry spells once established. They are ideal for the awkward corner of the garden where nothing else thrives. Space plants 8–12 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. Nasturtiums 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 nasturtiums include lavender, marigolds, garlic, chives. The companion planting finder can suggest combinations for your whole bed. Related reading: Calendula. Avoid planting nasturtiums where the same family (Tropaeolaceae) grew last year.
Pests and problems
The common pests and problems to watch for with nasturtiums 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. Nasturtiums are famous as a trap crop — aphids prefer them to your vegetables, which is useful if you plant them near the vegetable bed, but it means the nasturtiums themselves may be covered in aphids. That is the plant doing its job; wash them off with water if the infestation is heavy. Slugs can damage young plants, so protect seedlings in spring.
Harvest and storage
Both the flowers and the leaves are edible, with a peppery taste — pick them fresh for salads, and pick the flowers regularly to keep plants blooming. Seeds can be pickled as a caper substitute. Plants flower 50–60 days after sowing and keep going until the first frost, when they collapse at the first cold night.
Making the most of Zone 8
Nasturtiums are a working flower in Zone 8: they cover bare ground, attract pollinators, lure aphids away from vegetables, and give you edible flowers for the kitchen. Sow them after frost, give them poor soil, and let them ramble. 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: April in Zone 8 and Nasturtiums in Zone 1.
Frequently asked questions
When should I plant nasturtiums in Zone 8?
Work back from the average last frost around Mar 1–15: direct sow after the last frost (mid-march to april). Check your local extension service — these are zone averages, not exact dates for your garden.
How long do nasturtiums take to grow in Zone 8?
Seeds germinate in 7–14 days, and the crop takes 50–60 days to maturity. In Zone 8, cool soil can slow growth early in the season, so allow the longer end of the range.
Are nasturtium flowers edible?
Yes — nasturtium flowers and leaves are edible and taste peppery, like watercress. Pick them fresh and wash them before eating. Grow them without sprays if you plan to eat them, and check your local extension service if you are unsure about any plant's edibility.
What soil and spacing do nasturtiums need in Zone 8?
Nasturtiums need full sun and soil pH 6.0–7.5, spaced 8–12 inches apart. Dig in well-rotted compost, water deeply, mulch, and test your soil through your local extension service.