Potatoes are one of the most rewarding crops for a Zone 10 garden — and one of the few that are planted in the cool months. In Zone 10, potatoes are a winter crop: plant seed potatoes from December through February, let them grow through the mild winter, and dig them in spring, before the heat arrives. A potato planted in summer will struggle: hot soil stops tubers forming, and the plants will produce leaves but few potatoes.
That is the key point to understand. Potatoes sown in a Zone 10 summer will disappoint. Potatoes planted in January will give you a spring harvest of tender new potatoes that taste nothing like shop-bought ones.
Zone 10 at a glance
USDA Zone 10 covers the warmest parts of the United States, including southern Florida, southern coastal California, Hawaii and Puerto Rico. Winters are very mild, with average winter lows of 30 to 40°F, frost is rare, and the growing season runs nearly all year.
The average last spring frost is Jan 15–30 (frost rare) and the average first autumn frost is Dec 15–31 (frost rare) — USDA/NOAA averages, not exact dates, so check your local extension service before planting.
| Detail | Zone 10 guidance |
|---|---|
| Average winter low | 30 to 40°F |
| Average last spring frost | Jan 15–30 (frost rare) |
| Average first autumn frost | Dec 15–31 (frost rare) |
| Days to germination | 14–28 days |
| Days to maturity | 70–120 days |
| Sowing | direct sow |
| Sun | full sun |
| Soil pH | 5.0–6.0 |
| Spacing | 12 inches |
| Water needs | moderate |
| Cold tolerance | frost-tolerant |
When to plant potatoes in Zone 10
Plant potatoes in Zone 10 from December through February, for harvests from March through May, with a second planting in September through October for a late-autumn harvest. Seed potatoes sprout in 14–28 days and tubers mature in 70–120 days, so a January planting is ready to dig from March onwards. The average last spring frost in Zone 10 is Jan 15–30, with frost rare, and the average first autumn frost is Dec 15–31, with frost rare — those are USDA zone averages, not exact dates for any one garden, so always check your local extension service for your own frost dates. Potatoes are frost-tolerant, and the foliage can handle a light frost, though a hard freeze will damage it. Avoid planting from April through August: hot soil stops tubers forming, and the plants will produce leaves but few potatoes.
Work back from the frost dates: the planting calendar hub and the January in Zone 10 month guide show what else is happening at planting time.
Starting potatoes in Zone 10
Start potatoes from certified seed potatoes, not from shop-bought potatoes, which may carry disease and are often treated to stop them sprouting. Chit the seed potatoes first: set them in a light, cool place for a few weeks until short, sturdy shoots appear, then plant them 4–6 inches deep with the shoots facing up. Space them 12 inches apart in rows about 30 inches apart. Cover them with soil, and earth up — draw soil up around the stems — as the plants grow, so the developing tubers stay covered and do not turn green in the light. Water them in well after planting, and keep the soil moist through the growing season.
See also when to plant potatoes in Zone 8 for the same crop in a cooler zone.
Soil, spacing, sun and water
Potatoes need full sun and loose, well-drained, slightly acidic soil with a pH of 5.0–6.0 — the most acidic soil of any vegetable in this guide. Dig in well-rotted compost before planting, but avoid fresh manure, which encourages scab. Water needs are moderate: keep the soil evenly moist, especially while tubers are forming, because dry soil at that stage produces small, scabby potatoes. Water at the base in the morning, and mulch to hold moisture. The harvest date calculator can help you plan the bed before you plant.
Companion planting
Good companions for potatoes include beans, corn, cabbage, marigolds and horseradish. Beans fix nitrogen that potatoes use, corn provides light shade in the hottest weeks, and marigolds at the bed edge are said to deter pests. Sweet corn is another Zone 10 crop planted in the same cool-season window, and our guide to when to plant sweet corn in Zone 10 shows how the two can share the garden calendar. Avoid planting potatoes where tomatoes, peppers or eggplant grew last year — all are in the same family and share soil diseases — and keep them away from pumpkins and squash, which compete for space. The companion planting finder can suggest combinations for your whole bed.
Pests and problems
The common pests to watch for with potatoes are Colorado potato beetle, aphids, wireworms and flea beetles. Colorado potato beetle is the worst: the striped beetles and their red larvae strip the leaves fast — hand-pick them daily and check leaf undersides for orange egg masses. Aphids cluster on young leaves; wash them off with a strong jet of water. Wireworms chew the tubers from below; they are worst in ground that was recently grass. Flea beetles make small holes in the leaves of young plants; cover seedlings with insect mesh until they are established. Inspect plants regularly and act early — healthy, well-spaced plants resist pests better than stressed ones.
Harvest and storage
Potatoes take 70–120 days to maturity from planting, so Zone 10 winter plants set out in January are ready to dig from March onwards. For new potatoes, dig a plant when it flowers and take the small, tender tubers — eat them the same day. For maincrop potatoes, wait until the foliage dies back, then dig the whole row with a fork, taking care not to spear the tubers. Dig in dry weather, let the tubers dry in the sun for a few hours, then store them in a cool, dark, airy place in sacks or boxes — light turns them green, and green potatoes are poisonous. Do not wash potatoes before storing; brush the soil off and wash them just before cooking.
Frequently asked questions
When should I plant potatoes in Zone 10?
Plant from December through February, for harvests from March through May, with a second planting in September–October. Seed potatoes sprout in 14–28 days and tubers mature in 70–120 days. Avoid planting from April through August — hot soil stops tubers forming.
Why are my potatoes green?
Light — tubers exposed to light turn green and produce a bitter, poisonous compound. Earth up around the stems as plants grow so tubers stay covered, and store harvested potatoes in a cool, dark place.
Can I plant shop-bought potatoes?
It is better not to — shop potatoes may carry disease and are often treated to stop them sprouting. Buy certified seed potatoes, chit them in a light, cool place until short shoots appear, then plant them.