When to Plant Radishes in Arizona
Published: April 24, 2026
Arizona gardeners in Zone 9b enjoy an extended 50-week growing season for radish. Cool-season crops like radish do best in fall, winter, and early spring in Arizona — the hot summers bolt these plants before they can be harvested. This guide gives exact dates for Arizona based on your local frost calendar.
Radish Planting Dates for Arizona
| Start seeds indoors | Year-round |
| Last frost (average) | January 15 |
| Direct sow outdoors | December 11–21 |
| Expect first harvest | January 2 – January 10 |
| Fall crop start | November 26–December 6 |
| Fall harvest | December 18 |
| First fall frost (average) | December 31 |
Dates above assume Zone 9b, the most common zone in Arizona. Gardeners in cooler San Tan Valley (Zone 7b) plant 1–2 weeks later; warmer Tucson (Zone 9a) can plant 1–2 weeks earlier.
⚠ Direct sow radishes 4–6 weeks before last frost — one of the fastest crops in the garden. Ready in as little as 22 days. Succession plant every 2 weeks for continuous harvest.
Growing Radishes in Arizona's Climate
Arizona's warm Zone 9b climate makes radish a fall, winter, and early spring crop rather than a summer one. The cool-season window runs roughly October through April in Arizona — plant outside this window and the radish will bolt (send up a flower stalk and turn bitter) before it produces a harvestable crop.
Succession planting stretches the radish harvest window. Sow small amounts every two weeks from October through February — you will have staggered harvests rather than a single wave to process all at once. Bolt-resistant varieties extend the usable window an extra three to four weeks into warming weather.
Common radish pests to watch for in Arizona include Flea Beetle and Cabbage Root Maggot. The first line of defense is companion planting: Lettuce and Carrot planted nearby discourage several of these pests by confusing host-plant identification or repelling adults before they can lay eggs. Weekly garden walks in the early morning catch problems when they're still manageable.
Radish Garden Calendar for Arizona
| Month | Task | Notes |
|---|---|---|
| January | First harvest window opens | Radish begins producing 22–30 days after transplant |
| February | — | Off-season |
| March | — | Off-season |
| April | — | Off-season |
| May ← | Watch for bolting | Harvest promptly; spring heat arrives quickly |
| June | — | Off-season |
| July | — | Off-season |
| August | — | Off-season |
| September | — | Off-season |
| October | — | Off-season |
| November | Fall crop planting | Transplant or direct sow for fall harvest before frost |
| December | Direct sow seeds | Sow seeds 1/4–1/2 inch deep, 2 inches apart |
Radish Growing Tips for Arizona Gardeners
- •Thin to 2-inch spacing when seedlings are an inch tall — crowded radishes produce small woody roots.
- •Succession plant every 10–14 days from early spring through late spring for continuous harvest.
- •Arizona's cool-season radish plants best in October, November, and December for winter and early spring harvest. Spring plantings bolt before producing a harvestable crop.
- •Plant as a row marker for slow-germinating crops like carrots — radishes sprout in days and mark the rows.
Companion Planting for Radishes in Arizona
In Arizona's warm climate, planting radish with Lettuce and Carrot helps deter pests and improve soil. Avoid planting near Hyssop and Grape, which inhibit radish growth through root chemistry or shared pest pressure. See the full radish companion planting guide for the complete list.
Radishes Planting Dates by City in Arizona
Top cities in Arizona — select for city-level frost dates and planting calendars.
Frequently Asked Questions
When should I plant radish in Arizona?
In Arizona (Zone 9b), start radish seeds indoors around Year-round and transplant outdoors around null — 0 weeks after the state's average last frost of January 15.
What is the last frost date in Arizona?
Arizona's average last frost date is January 15 in the state's most common Zone 9b. Frost dates vary by city — higher elevations and northern counties run 1 to 3 weeks later than the state average. See the city list below for city-level frost dates.
Can I grow radish year-round in Arizona?
radish is a cool-season crop in Arizona, with spring and fall windows. Summer heat bolts the plants before they can produce a harvestable crop. Succession planting every 2–3 weeks stretches the harvest window.
What radish varieties grow best in Arizona?
For Arizona's Zone 9b, consult a local nursery or extension office for radishes variety recommendations.
When do I start radish seeds indoors in Arizona?
Radish does not need indoor starting in Arizona — direct sow around December 11–21 once soil reaches 40°F. Indoor starting is not recommended for this crop because radish transplants poorly.