Build Your Seed Starting Schedule

Select your plants and enter your frost date — we'll tell you exactly when to start every seed.

Your Last Frost Date
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Select Your Plants
Your Seed Starting Schedule
Plant Start Indoors Transplant / Direct Sow Notes
How It Works

How to Use Your Seed Starting Schedule

Three steps from schedule to a thriving transplant.

1

Find Your Frost Date

Enter your ZIP code above. The tool pulls your average last spring frost from 30-year NOAA climate data and uses it as the anchor for every planting date in your schedule.

2

Select Your Plants

Check off every vegetable or herb you plan to grow. Each plant has a custom start window — tomatoes need 6–8 weeks indoors, while cucumbers only need 3–4. The schedule handles the math.

3

Print & Follow the Calendar

Your personalized week-by-week schedule shows exactly when to sow each crop, when to pot up seedlings, and when it's safe to transplant outdoors — all timed to your frost date.

Seed Starting Guide

Everything You Need to Know About Starting Seeds Indoors

Why Start Seeds Indoors?

Starting seeds indoors extends your growing season by weeks or even months. In cooler climates, crops like tomatoes, peppers, and eggplant need 8–10 weeks of warm indoor growth before outdoor temperatures are safe. Without indoor starts, these crops may never ripen before fall frost arrives. Even in warm climates like Texas, starting indoors gives transplants a head start on summer heat before conditions become stressful.

What You Need to Get Started

  • Seed-starting mix — lighter and more sterile than potting soil
  • Cell trays or small pots — 6-cell or 72-cell trays work well
  • Grow lights or a very sunny south-facing window
  • A heat mat — speeds germination for warm-season crops
  • Labels and a waterproof marker — you will forget which is which
  • A spray bottle — for gentle watering of fragile seedlings

Seed Starting Timing by Crop Type

Crop Weeks Before Last Frost Method
Tomatoes 6–8 weeks Indoors
Peppers 8–10 weeks Indoors
Eggplant 8–9 weeks Indoors
Broccoli / Cabbage 4–6 weeks Indoors
Cucumbers / Squash 3–4 weeks Indoors or direct
Lettuce / Greens 4–6 weeks Indoors or direct
Beans / Corn Direct sow after frost Outdoors only
Hardening Off — Don't Skip This Step

Seedlings raised indoors are accustomed to stable temperatures and no wind. Before transplanting, harden them off over 7–10 days by placing them outdoors in a sheltered spot for a few hours each day, gradually increasing exposure. Skipping this step causes transplant shock — wilted, yellowed plants that take weeks to recover, if they survive at all.

Common Questions

Seed Starting FAQ

Seed-starting mix is a fine-textured, soilless blend — typically peat moss or coco coir, perlite, and vermiculite — designed to retain moisture while draining well. Potting soil is too dense for germinating seeds, can harbor pathogens, and may compact in small cells, suffocating delicate roots. Always use a dedicated seed-starting mix until you pot up into larger containers.
A south-facing window can work for cool-season crops and herbs, but warm-season crops like tomatoes and peppers almost always need a grow light. Windows deliver low-intensity, angled light that causes seedlings to stretch and become "leggy" — tall, weak, and prone to falling over. A basic shop light or LED grow light hung 2–4 inches above seedlings for 14–16 hours per day makes an enormous difference in transplant quality.
The most common cause of slow or failed germination is soil temperature. Peppers, for example, germinate best between 80–85°F — room temperature (68–70°F) is too cold and germination can take 3–4 weeks instead of 7–10 days. A seedling heat mat placed under your trays brings soil temperature into the ideal range. Other causes include seed depth (most small seeds need only ⅛–¼ inch coverage), old seed, or overwatered soil that drowned the seed.
Damping off is a fungal disease that causes seedlings to suddenly collapse at soil level — the stem rots through, and the seedling tips over and dies within hours. It is caused by overwatering, poor air circulation, and using non-sterile soil. Prevent it by using fresh seed-starting mix each year, watering from below (set trays in water and let them soak up moisture), keeping a small fan running for air circulation, and avoiding misting seedlings with cold water.
Most seed-starting mixes contain little or no fertilizer — they're designed to be inert so germination rates stay high. Once seedlings develop their first set of true leaves (the second set to appear, after the initial seed leaves), begin feeding with a diluted balanced liquid fertilizer at half the recommended dose. Once per week is sufficient. Over-fertilizing seedlings causes salt burn — brown leaf edges — and can slow growth.
A transplant-ready seedling has 2–4 sets of true leaves, a stem that's sturdy enough to stand on its own, and roots that hold the potting mix together when removed from its cell. It should also have been hardened off — gradually acclimated to outdoor conditions over 7–10 days. The outdoor soil temperature should be reliably above 60°F for warm-season crops. Transplanting too early stresses plants; transplanting too late with a root-bound seedling also slows establishment.
Next Step

Find Your Frost Dates First

Your seed starting schedule is built around your last frost date. Look it up in seconds with our Frost Date Calculator.

Check Frost Dates Companion Planting Guide