🌱 Seed Starting Guide
Exactly when to start seeds indoors for zones 3–10 — with last frost dates, weeks-before-frost countdown, and a printable calendar for every crop.
Get our zone-based seed starting chart — print it and stick it on the fridge.
No spam. Unsubscribe anytime.
Your last frost date is the anchor for every seed starting calculation. Everything works backward from this date.
Find your zone below. Then use the crop timing table to count backward from your last frost date to determine when to start seeds indoors. For example: Zone 6 last frost = April 15. Tomatoes need 6–8 weeks before transplant. Start tomatoes February 18 – March 4.
| Zone | Avg Low Temp | Avg Last Spring Frost | Avg First Fall Frost | Growing Season | Example Cities |
|---|---|---|---|---|---|
| 3 | -40 to -30°F | May 15–June 1 | Aug 15–Sept 15 | 75–100 days | Fargo ND, Duluth MN, interior Alaska |
| 4 | -30 to -20°F | May 1–May 15 | Sept 1–Oct 1 | 105–130 days | Minneapolis MN, Burlington VT, Boise ID |
| 5 | -20 to -10°F | Apr 15–May 1 | Oct 1–Oct 15 | 135–160 days | Chicago IL, Boston MA, Denver CO |
| 6 | -10 to 0°F | Apr 1–Apr 15 | Oct 15–Nov 1 | 165–180 days | Philadelphia PA, St. Louis MO, Portland OR |
| 7 | 0 to 10°F | Mar 15–Apr 1 | Nov 1–Nov 15 | 185–200 days | Washington DC, Raleigh NC, Oklahoma City OK |
| 8 | 10 to 20°F | Mar 1–Mar 15 | Nov 15–Dec 1 | 210–240 days | Seattle WA, Dallas TX, Savannah GA |
| 9 | 20 to 30°F | Feb 1–Feb 28 | Dec 1–Dec 15 | 250–280 days | San Jose CA, Houston TX, Phoenix AZ |
| 10 | 30 to 40°F | Jan 15–Feb 15 (or none) | Dec 15–Jan 15 | 300–365 days | Miami FL, Los Angeles CA, Honolulu HI |
USDA zones are based on average minimum winter temperatures — not frost dates. Two locations in zone 6 can have last frost dates 3–4 weeks apart based on elevation, proximity to water, or urban heat. Use your local average last frost date (check your county extension office or a site like FrostDate.com) for maximum accuracy.
Weeks before last frost (WBF) to start seeds indoors. "Direct sow" means plant directly in the garden — no indoor starting needed.
| Crop | Weeks Before Last Frost (Start Indoors) | Transplant Timing | Germination Temp | Notes |
|---|---|---|---|---|
| 🍅 Tomato | 6–8 weeks | After last frost, soil 60°F+ | 70–80°F | Most common beginner mistake: starting too early. 8 weeks is the max unless you have grow lights. |
| 🫑 Pepper | 8–10 weeks | 2 weeks after last frost | 75–85°F | Needs warmth to germinate — use heat mat. Slow starters; never rush. |
| 🍆 Eggplant | 8–10 weeks | 2 weeks after last frost | 75–85°F | Same timing as peppers. Needs warm soil at transplant. |
| 🥦 Broccoli | 6–8 weeks | 2–4 weeks BEFORE last frost | 60–70°F | Cool-season crop. Transplant out early; tolerates light frost. |
| 🥬 Cabbage | 6–8 weeks | 3–4 weeks before last frost | 55–70°F | Can start a fall crop 10–12 weeks before first fall frost. |
| 🥦 Cauliflower | 6–8 weeks | 2–4 weeks before last frost | 60–70°F | More temperature-sensitive than broccoli. Blanch heads for white color. |
| 🌿 Kale/Chard | 4–6 weeks | 4–5 weeks before last frost | 55–65°F | Direct sow also works. Start indoors to get a 3-week jump. |
| 🥒 Cucumber | 3–4 weeks | After last frost, soil 70°F+ | 70–90°F | Don't start too early — cucumbers hate being root-bound. |
| 🎃 Squash/Pumpkin | 3–4 weeks | After last frost | 70–90°F | Start late — they outgrow indoor space quickly. Direct sow often better. |
| 🍈 Melon | 3–4 weeks | 2 weeks after last frost, warm soil | 75–85°F | Only start indoors in zones 5 and colder. Direct sow in zones 6+. |
| 🌸 Celery | 10–12 weeks | 2 weeks before last frost | 65–70°F | Longest lead time of any vegetable. Needs consistent moisture. Tricky for beginners. |
| 🌻 Basil | 4–6 weeks | After last frost, when nights are 50°F+ | 70–80°F | Cold-sensitive. Don't transplant until truly warm. Don't overwater seedlings. |
| 🌿 Parsley | 8–10 weeks | 2 weeks before last frost | 65–70°F | Very slow to germinate (2–3 weeks). Soak seeds overnight before sowing. |
| 🌺 Lavender | 8–12 weeks | After last frost | 65–70°F | Slow germination (2–4 weeks). Surface sow (needs light). Consider buying transplants instead. |
| 💐 Snapdragon | 8–10 weeks | 2–4 weeks before last frost | 60–65°F | Cool-season annual. Surface sow; needs light. Tolerates frost. |
| 🥕 Carrot | Direct sow only | 4–6 weeks before last frost | 50–80°F | Taproots don't transplant — sow directly in the garden. |
| 🥬 Lettuce | 4–6 weeks or direct | 3–4 weeks before last frost | 45–65°F | Surface sow (needs light). Quick germination. Succession sow every 2 weeks. |
| 🥦 Peas | Direct sow only | 6–8 weeks before last frost | 45–65°F | Sow directly as soon as soil can be worked. Transplanting damages roots. |
| 🫘 Beans | Direct sow only | After last frost, soil 60°F+ | 60–85°F | Fast-maturing; no indoor start needed or beneficial. |
| 🌻 Sunflower | 2–3 weeks or direct | After last frost | 65–85°F | Fast growers. Barely worth starting indoors. Direct sow after frost. |
What to start each month based on your zone — at a glance.
Most seed starting failures happen before the seedling ever goes outdoors. Here's what to avoid.
Starting too early. The most universal mistake. Six weeks of indoor growing is enough for tomatoes. Eight weeks produces tall, root-bound, stressed plants that transplant poorly and produce less fruit than properly-timed 6-week plants. If you have a big grow light setup, you can push to 8 weeks. Without artificial lighting, stay at 6 weeks max.
Using native soil or outdoor garden soil. Never start seeds in outdoor soil. It's too heavy, compacts instantly in small cells, and carries pathogens and weed seeds. Use dedicated seed-starting mix — fine-textured, sterile, low-nutrient. Switch to potting mix once seedlings have true leaves.
Skipping hardening off. Seedlings grown indoors under grow lights have never experienced wind, UV radiation, or temperature swings. Moving them directly outside causes "transplant shock" and often kills them. Two weeks before transplanting: set them outside in a sheltered spot for increasing hours each day (start at 1–2 hours, build to full day by the end).
Overwatering. Seed starting mix should be moist, never wet. Seedlings rot at the base (damping off) when overwatered, and no recovery is possible. Water from below by setting trays in water for 10 minutes, then letting them drain.
A south-facing window provides roughly 6–8 hours of light in spring — not enough for tomatoes and peppers, which need 14–16 hours to grow compact and healthy. Without supplemental lighting, start seedlings later (6 weeks, not 8) and accept leggier plants. With a simple LED grow light set 2–3 inches above seedlings on a timer, you can start on schedule and produce strong transplants every time.
Download our zone-based printable: find your last frost date, count back by crop, and have a personalized seed starting schedule in 5 minutes.
No spam. Unsubscribe anytime.
Enter your zone and get a personalized planting calendar — plus AI-powered advice for what to grow and when.
Put your harvest to work — these recipes pair with what this guide helps you grow.
Eggs poached directly in a spiced tomato and pepper sauce. One pan, minimal cleanup, and t…
⏱ 30 minA fast, classic omelette showcasing the brightness of garden herbs. Perfect when you've go…
⏱ 10 minPortable, make-ahead egg cups baked in a muffin tin with whatever veg you have. Great for …
⏱ 25 minCrispy pan-fried cakes that are the best answer to a zucchini surplus. Serve with a dollop…
⏱ 20 minA hearty one-pan hash using whatever vegetables are ready. Potatoes optional — this works …
⏱ 20 min