🌱 Seed Starting Schedule
Calculate optimal indoor and outdoor seed starting dates based on your last frost date and crop selection
Your Result:
🍅 Tomatoes → Start Indoors: March 15
Last Frost: May 1 • Zone 6 • 6-8 weeks before frost
📅 Complete Planting Timeline
📊 Detailed Schedule Example
💡 Pro Tips
- Start warm-season crops (tomatoes, peppers) indoors 6-8 weeks before last frost
- Cool-season crops (lettuce, broccoli) can tolerate light frosts
- Direct sow beans, corn, and squash after soil warms to 60°F
- Use grow lights or south-facing windows for indoor seedlings
How to Use This Seed Starting Schedule
This seed starting calculator helps you determine the optimal dates for starting seeds indoors and transplanting or direct sowing outdoors based on your local frost dates. Whether you're growing vegetables, herbs, or flowers, proper timing is crucial for gardening success.
- Enter Your Last Frost Date: Input your area's average last spring frost date. This is the cornerstone of your planting schedule. If unsure, search online with your ZIP code or consult your local agricultural extension office.
- Select Your Crop: Choose from our comprehensive list of vegetables, herbs, and flowers. Each crop shows its recommended indoor starting time (e.g., "6-8 weeks before last frost") to help you understand the timing.
- Choose Your Growing Zone: Select your USDA Hardiness Zone for regional adjustments. Different zones have varying growing season lengths and temperature patterns that affect planting schedules.
- Optional Settings: Enable succession planting to see multiple sowing dates for continuous harvests, or add fall planting calculations if you want to grow cool-season crops for autumn harvest.
- Generate Your Schedule: Click the calculate button to receive your personalized planting calendar with specific dates for indoor seed starting, hardening off, and outdoor transplanting or direct sowing.
The calculator accounts for each crop's specific needs, from slow-growing celery that needs 10-12 weeks indoors to quick-growing radishes that can be direct sown weeks before the last frost. Use the generated schedule to plan your seed purchases, prepare your growing space, and ensure successful garden timing.
How It Works
The seed starting schedule calculator uses established horticultural timing guidelines and your local frost dates to create a personalized planting calendar:
- Frost Date Calculation: Uses your last spring frost date as the primary reference point for timing all spring plantings
- Crop-Specific Timing: Each vegetable, herb, and flower has predetermined indoor starting windows (3-12 weeks before last frost) based on growth rates and temperature needs
- Indoor Start Date: Subtracts the crop's required indoor growing period from your last frost date to determine when to sow seeds indoors
- Transplant Window: Calculates safe outdoor planting dates based on frost tolerance (hardy crops can go out before last frost, tender crops must wait until after)
- Direct Sow Timing: Determines when soil is warm enough for direct seeding based on crop requirements and typical soil warming patterns
- Zone Adjustments: Modifies timing slightly based on USDA Hardiness Zone to account for regional climate variations
- Hardening Period: Automatically includes a 7-10 day hardening off period before transplant dates for indoor-started seedlings
- Succession Planting: Calculates multiple planting dates at 2-3 week intervals for crops suitable for successive sowings
- Fall Schedule: For fall planting, counts backward from first frost date to determine when to start fall crops
The tool combines these calculations to produce a comprehensive timeline showing exactly when to start seeds, when to transplant, and when to direct sow for optimal garden success.
When You Might Need This
- • Plan your spring vegetable garden by calculating when to start tomato, pepper, and eggplant seeds indoors
- • Determine optimal outdoor planting dates for direct-sown crops like beans, corn, and squash after frost danger passes
- • Schedule succession plantings of lettuce and greens for continuous harvest throughout the growing season
- • Calculate fall planting dates for cool-season crops based on your first frost date
- • Plan a herb garden with proper indoor starting times for basil, oregano, and parsley
- • Coordinate flower seed starting for marigolds, zinnias, and petunias to ensure blooms all summer
- • Time your brassica plantings (broccoli, cabbage, cauliflower) for optimal growth in cool weather
- • Schedule root vegetable sowings for carrots, radishes, and beets at the right soil temperature
- • Plan a greenhouse or cold frame schedule for extending your growing season
- • Create a month-by-month planting calendar for your entire garden based on frost dates
Frequently Asked Questions
How do I find my last frost date?
Your last frost date is the average date of the final spring frost in your area. You can find it by searching online for 'last frost date' with your ZIP code, checking with your local agricultural extension office, or using the NOAA climate data. Most areas have historical averages that gardeners rely on, though actual dates can vary by 2-3 weeks each year. Always monitor local weather forecasts as your last frost date approaches.
What's the difference between starting seeds indoors vs direct sowing?
Starting seeds indoors gives plants a head start in controlled conditions, essential for warm-season crops like tomatoes and peppers that need a long growing season. Indoor starting happens 4-12 weeks before the last frost, depending on the crop. Direct sowing means planting seeds directly in the garden soil, which works best for crops that don't transplant well (like carrots and beans) or grow quickly (like radishes and lettuce). Some crops can be done either way, with indoor starting providing earlier harvests.
What does 'hardening off' mean and why is it important?
Hardening off is the process of gradually acclimating indoor-grown seedlings to outdoor conditions over 7-10 days before transplanting. Start by placing seedlings outside in a shaded, protected spot for 1-2 hours, gradually increasing exposure to sun, wind, and temperature changes each day. This prevents transplant shock, sunburn, and wind damage. Skipping this step often results in stunted growth or plant death, as tender indoor seedlings aren't prepared for harsh outdoor conditions.
Can I plant before my last frost date?
Yes, many cool-season crops can be planted 2-6 weeks before the last frost date. Hardy vegetables like peas, spinach, lettuce, and radishes can tolerate light frosts and even taste better when grown in cool weather. Brassicas (broccoli, cabbage) can also handle cold but may need protection from hard freezes. Use row covers, cold frames, or cloches for extra protection. However, warm-season crops like tomatoes, peppers, and squash must wait until after the last frost or they'll be killed by cold temperatures.
How do succession planting dates work?
Succession planting involves sowing the same crop at 2-3 week intervals to ensure continuous harvest rather than all plants maturing at once. This works especially well for fast-growing crops like lettuce, radishes, beans, and corn. For example, plant lettuce every 2 weeks from early spring through early summer, then again in late summer for fall harvests. The calculator can show multiple planting dates, helping you plan when to start each succession for steady production throughout the season.