When to Start Seeds Indoors in Zone 9
Your month-by-month seed-starting calendar, timed to a last frost around Late January – late February.
- Min Winter Temp
- 20 to 30 °F / -7 to -1 °C
- Last Spring Frost
- Late January – late February
- First Fall Frost
- Early December – early January
- Growing Season
- 270–310 days
- Annual Rainfall
- 10–55 in
Seed starting in Zone 9
Starting seeds indoors gives heat-loving crops the head start they need to ripen within Zone 9's season. Because everything is timed to your last spring frost — around Late January – late February in Zone 9 — the calendar below shows exactly which month to start each crop. Count back from your transplant date, sow under bright light, and harden seedlings off before they go outside.
Zone 9 seed-starting calendar
January
All January tasks →Start tomatoes and peppers indoors
Zone 9 transplant dates for tomatoes and peppers are March–April, making late January the right time to start seeds indoors under lights. Starting on time gives transplants the 8–10 weeks needed for robust root systems before going in the ground.
Sow 2 seeds per cell, ¼ inch deep, in moist seed-starting mix. Maintain 75–80°F soil temperature with a heat mat. Thin to 1 seedling per cell after germination. Provide 14–16 hours of light daily.
Sow ¼ inch deep; peppers need 80–85°F soil temperature to germinate — use a heat mat and be patient (10–21 days). Start 10–12 weeks before outdoor transplant date.
Sow ¼ inch deep with bottom heat (80°F). Eggplant is slow to establish; starting in late January gives it the head start it needs for Zone 9's long warm season.
February
All February tasks →Start warm-season transplants indoors
If tomatoes and peppers were not started in January, start them immediately in February. Last frost in Zone 9 is typically late January to late February, meaning outdoor transplant dates in March are approaching fast.
Sow ¼ inch deep in seed-starting mix with bottom heat at 75–80°F. Expect germination in 5–10 days. Move to bright light immediately after sprouting to prevent leggy seedlings. Pot up to 4-inch containers when 2 true leaves appear.
Sow ¼ inch deep; keep at 80–85°F for best germination rates. Peppers started in February will be 6–8 weeks old at March transplant time — the minimum size for successful outdoor establishment.
Sow ¼ inch deep at 80°F. Eggplant needs warm soil to thrive; early indoor starting ensures transplants are well-established before they go out in Zone 9's warm spring.
Sow seeds on the surface, pressing lightly into moist mix. Basil germinates in 5–7 days at 70°F. Start 6–8 weeks before last frost; do not transplant outdoors until nights stay above 55°F.
April
All April tasks →Start second-succession warm-season crops indoors
Start a second round of tomato and pepper transplants in April for a late-summer/fall harvest. Zone 9's growing season extends to December, meaning plants set out in June or July from April-started seeds produce a full autumn crop.
Cherry Tomatoes (second succession)
Sow ¼ inch deep; grow under lights for 6–8 weeks before transplanting in late May or June. Cherry tomatoes handle Zone 9's summer heat better than beefsteak types and continue producing into November.
Start a second round now for fall production. Pepper plants set out in June after spring plants decline will fruit prolifically September–November in Zone 9. Keep indoors under lights until nighttime temperatures are reliably above 60°F.
Start fall tomato transplants under lights
Starting a second crop of tomatoes and peppers in late May gives Zone 9 gardeners vigorous transplants ready for late July–August planting for a full autumn harvest before December frost.
Sow ¼ inch deep under grow lights. Heat-tolerant varieties like 'Solar Fire', 'Heatmaster', or 'Sweet 100 Cherry' perform best for Zone 9's fall crop. Grow under lights for 8–10 weeks before transplanting in late July or August.
Sow ¼ inch deep at 80°F. Fall peppers set in August will fruit heavily in September–November in Zone 9 as temperatures moderate — often outyielding spring-planted crops.
July
All July tasks →Start fall tomatoes, peppers, and brassicas indoors
Late July is the critical window for starting fall transplants indoors. Zone 9's fall garden — one of the most productive of the year — depends on having vigorous transplants ready for August–September planting.
Sow ¼ inch deep in seed-starting mix under grow lights at 75–80°F. Choose fast-maturing, heat-tolerant varieties: 'Celebrity', 'Sweet 100', or 'Juliet'. Grow under lights for 8 weeks before transplanting in late September.
Start under lights at 80°F. Fall peppers transplanted in September will fruit heavily October–December in Zone 9. Choose varieties with good cool-weather fruit set like 'Gypsy' or 'King of the North'.
Sow in cell trays, 2 seeds per cell, thinning to 1. Grow under lights or in a bright, air-conditioned space — outdoor temperatures are too extreme for delicate brassica seedlings in July. Transplant outdoors in late August or September.
Start seeds in mid-late July for September transplanting. Cauliflower is more cold-sensitive and heat-sensitive than broccoli — timing is critical. Varieties like 'Snow Crown' mature in 55 days and are ideal for fall planting.
Sow in cell trays for September–October transplanting. Fall cabbage planted in Zone 9 forms heads in November–December. 'Savoy Perfection' and 'Storage No. 4' are good choices for Zone 9 fall plantings.
August
All August tasks →Start slow-maturing fall crops indoors
Some fall crops benefit from starting indoors in August to get a head start before outdoor temperatures are fully moderate. This includes lettuce varieties prone to heat dormancy and slow-growing brassicas.
Start cell trays indoors in air-conditioned space where temperatures stay below 75°F. Lettuce seed germinates poorly above 80°F. Grow for 3–4 weeks before transplanting outdoors in September. Use heat-tolerant varieties like 'Nevada' or 'Jericho'.
Celery is slow-growing (120 days) and can be started indoors in August for a December–January harvest in Zone 9. Sow seeds on the surface (they need light) at 65–70°F. Pot up once and transplant outdoors in October.
Sow seeds ¼ inch deep in cell trays indoors. Leeks transplanted in September–October will be ready for harvest in January–March of next year. 'King Richard' and 'Giant Musselburgh' are reliable Zone 9 performers.
December
All December tasks →Start onions, leeks, and early flower seeds indoors
Late December is the right time to start long-season crops indoors that need 12–14 weeks of growth before outdoor transplanting in March–April. Onions, leeks, and slow-growing flowers benefit from early starts.
Sow ¼ inch deep in cell trays, 3–4 seeds per cell; thin to 1–2. Grow under lights at 65–70°F. December-started onions will be transplanted outdoors in March–April. Choose short-day varieties for Zone 9: 'Texas 1015 Supersweet', 'Granex Yellow', 'Red Burgundy'.
Sow ¼ inch deep, 1 seed per cell, under grow lights. Leeks need 10–12 weeks to reach transplant size. December-started leeks are ready for outdoor transplanting in March for summer harvest.
Lisianthus
Lisianthus needs 5–6 months from seed to bloom — start in December for summer flowers. Sow on the surface of moist seed-starting mix; seeds need light to germinate. Keep at 70–75°F. One of the most rewarding cut flowers for Zone 9 summer gardens.
How to start seeds indoors
- 1
Count back from your last frost. Most warm-season crops start 6–8 weeks before; peppers and eggplant 8–10 weeks.
- 2
Sow into a clean seed-starting mix, at the depth on the packet, and keep it consistently warm (a heat mat speeds germination).
- 3
Give seedlings strong light as soon as they sprout — a sunny window is rarely enough; a shop light a few inches above works well.
- 4
Pot up if seedlings outgrow their cells before it’s warm enough to plant out.
- 5
Harden off over 7–10 days — gradually expose them to outdoor sun and wind — before transplanting after your last frost.
Seed starting in Zone 9: common questions
When should I start seeds indoors in Zone 9?＋
In Zone 9, the indoor-sowing months are January, February, April, May, July, August, and December, timed to a last spring frost around Late January – late February. Start the longest-season crops first and quicker crops closer to your transplant date.
What seeds can I start indoors in Zone 9?＋
Common crops to start indoors in Zone 9 include Tomatoes, Peppers, Eggplant, Basil, Cherry Tomatoes (second succession), Peppers (second succession), Fall Tomatoes, Fall Peppers. Warm-season crops like tomatoes and peppers benefit most from an indoor head start.
How many weeks before the last frost should I start seeds in Zone 9?＋
It depends on the crop: peppers and eggplant want 8–10 weeks, tomatoes 6–8 weeks, and quicker crops like cucumbers or squash just 3–4 weeks before transplanting. Count back from Zone 9's last frost (around Late January – late February) to find each start date.
Zone 9 overview →
Frost dates, climate, and everything to grow here.
Monthly calendars →
What to sow, transplant, and harvest each month.
Plant growing guides →
Full care guides for every crop in the calendar.