Seed-Starting Date Calculator | When To Start Seeds Indoors

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Seed-Starting Date Calculator

The right time to start your seeds indoors varies significantly by crop and location, ranging anywhere from 2–16 weeks prior to transplanting. Use this calculator to ascertain when to start seeds indoors and then to transplant outside, based on the frost-free date in your area.

Enter spring frost-free date (include year):

mm/dd/yyyy Date Enter
Crop Number of weeks to start seeds before setting-out date When to start inside Setting-out date
From To Safe time to set out plants (relative to frost-free date) From To

VEGETABLES

Artichoke 8 to 12 19-Jul on frost-free date 13-Sep
Beets* 5 to 6 19-Jul 2-Aug 2 weeks before 30-Aug
Broccoli (standard) 3 to 4 19-Jul 2-Aug 2 weeks before 30-Aug
Cabbage 4 to 6 5-Jul 16-Aug 4 weeks before 16-Aug 13-Sep
Cauliflower 4 to 6 19-Jul 16-Aug 2 weeks before 30-Aug 13-Sep
Celery & Celeriac 10 to 12 28-Jun 12-Jul 1 week after 20-Sep
Collards 4 to 6 5-Jul 19-Jul 4 weeks before 16-Aug
Cucumber 3 to 4 23-Aug 6-Sep 1 to 2 weeks after 20-Sep 27-Sep
Eggplant 6 to 8 19-Jul 9-Aug 2 to 3 weeks after 27-Sep 4-Oct
Kale 4 to 6 5-Jul 19-Jul 4 weeks before 16-Aug
Kohlrabi* 4 to 6 5-Jul 19-Jul 4 weeks before 16-Aug
Leeks 8 to 10 21-Jun 5-Jul 2 weeks before 30-Aug
Lettuce 4 to 5 12-Jul 26-Jul 3 to 4 weeks before 16-Aug 23-Aug
Melons 3 to 4 30-Aug 6-Sep 2 weeks after 27-Sep
Okra* 4 to 6 16-Aug 13-Sep 2 to 4 weeks after 27-Sep 11-Oct
Onions 8 to 10 7-Jun 21-Jun 4 weeks before 16-Aug
Peppers 8 2-Aug 2 weeks after 27-Sep
Pumpkins 3 to 4 30-Aug 6-Sep 2 weeks after 27-Sep
Spinach 4 to 6 21-Jun 26-Jul 3 to 6 weeks before 2-Aug 23-Aug
Squash 3 to 4 30-Aug 6-Sep 2 weeks after 27-Sep
Swiss Chard 5 to 6 19-Jul 2-Aug 2 weeks before 30-Aug
Tomatoes 5 to 6 26-Jul 16-Aug 1 to 2 weeks after 20-Sep 27-Sep
Watermelon 3 to 4 30-Aug 6-Sep 2 weeks after 27-Sep

HERBS
Basil* 6 9-Aug 1 week after 20-Sep
Chamomile 4 to 6 14-Jun 28-Jun 1 week after 23-Aug 30-Aug
Parsley 9 to 10 14-Jun 28-Jun 1 week after 23-Aug 30-Aug
Sage 6 to 8 14-Jun 28-Jun 1 week after 23-Aug 30-Aug
Thyme 8 to 10 14-Jun 28-Jun 1 week after 23-Aug 30-Aug

FLOWERS
Ageratum 6 to 8 19-Jul 2-Aug on frost-free date 13-Sep
Agrostemma (Corn Cockle)* 4 to 5 19-Jul 2-Aug on frost-free date 13-Sep
Alyssum 4 to 5 9-Aug 23-Aug 1 week after 20-Sep
Amaranthus 4 to 6 9-Aug 23-Aug 1 week after 20-Sep
Ammi (False Queen Anne's Lace)* 4 to 6 19-Jul 2-Aug on frost-free date 13-Sep
Ammobium 5 to 6 19-Jul 2-Aug 1 week after 13-Sep
Artemisia (Sweet Annie) 5 to 6 19-Jul 2-Aug on frost-free date 13-Sep
Asclepias (Butterfly Weed) 7 to 9 21-Jun 5-Jul on frost-free date 13-Sep
Aster, China 6 to 8 19-Jul 2-Aug on frost-free date 13-Sep
Atriplex 4 to 6 19-Jul 2-Aug 1 week after 13-Sep
Bells of Ireland* 6 to 8 19-Jul 2-Aug on frost-free date 13-Sep
Calendula* 4 to 5 19-Jul 2-Aug on frost-free date 13-Sep
Cardoon 6 to 8 19-Jul 2-Aug on frost-free date 13-Sep
Carthamus (Safflower)* 4 to 5 2-Aug 16-Aug on frost-free date 13-Sep
Celosia 6 to 8 26-Jul 9-Aug 1 week after 20-Sep
Centaurea (Bachelor's Button)* 3 to 4 19-Jul 2-Aug on frost-free date 13-Sep
Cerinthe 6 19-Jul 2-Aug 1 week after 13-Sep
Clarkia 4 19-Jul 2-Aug 1 week after 13-Sep
Columbine 8 to 10 19-Jul 2-Aug 1 week after 13-Sep
Cosmos* 5 to 7 26-Jul 9-Aug on frost-free date 13-Sep
Craspedia (Drumstick Flower) 6 to 8 5-Jul 19-Jul on frost-free date 13-Sep
Dahlia (from seed) 4 to 5 19-Jul 2-Aug 1 week after 13-Sep
Delphinium 10 to 16 24-May 5-Jul on frost-free date 13-Sep
Dianthus (Sweet William) 6 to 8 7-Jun 28-Jun 1 to 2 weeks before 30-Aug 6-Sep
Didiscus 4 to 6 19-Jul 2-Aug 1 week after 13-Sep
Digitalis (Foxglove) 10 to 12 21-Jun 5-Jul on frost-free date 13-Sep
Dusty Miller 8 to 10 19-Jul 2-Aug 1 week after 13-Sep
Echinacea 8 to 10 19-Jul 2-Aug 1 week after 13-Sep
Echinops 6 to 8 19-Jul 2-Aug 1 week after 13-Sep
Eryngium 10 to 16 19-Jul 2-Aug 1 week after 13-Sep
Eucalyptus 8 to 10 21-Jun 5-Jul on frost-free date 13-Sep
Euphorbia (Snow-on-the-Mountain)* 4 to 6 2-Aug 16-Aug on frost-free date 13-Sep
Forget-Me-Not (Cynoglossom) 3 to 4 12-Jul 19-Jul on frost-free date 13-Sep
Gomphrena (Globe Amaranth) 6 to 8 19-Jul 2-Aug on frost-free date 13-Sep
Gypsophila 6 to 8 19-Jul 2-Aug 1 week after 13-Sep
Helianthus maximillianii 8 to 10 5-Jul 19-Jul on frost-free date 13-Sep
Helipterum 6 to 8 19-Jul 2-Aug 1 week after 13-Sep
Hibiscus 6 to 8 12-Jul 26-Jul 1 week after 20-Sep
Hyacinth Bean 4 to 6 9-Aug 23-Aug 1 week after 20-Sep
Kale, Ornamental 4 to 6 19-Jul 2-Aug on frost-free date 13-Sep
Larkspur* 5 to 7 19-Jul 2-Aug on frost-free date 13-Sep
Lisianthus 12 to 13 14-Jun 21-Jun on frost-free date 13-Sep
Lupine 4 to 8 5-Jul 19-Jul 2 weeks before 30-Aug
Marigold 4 to 6 26-Jul 9-Aug 1 week after 20-Sep
Matricaria 5 to 7 19-Jul 2-Aug 1 week after 13-Sep
Monarda (Bee Balm) 7 to 9 19-Jul 2-Aug on frost-free date 13-Sep
Nasturtium 3 to 4 19-Jul 2-Aug 1 week after 13-Sep
Nicotiana 5 to 6 19-Jul 2-Aug 1 week after 13-Sep
Nigella* 4 to 6 2-Aug 16-Aug on frost-free date 13-Sep
Phlox* 4 to 6 19-Jul 1 to 2 weeks before 30-Aug 6-Sep
California Poppy* 2 to 3 23-Aug 30-Aug on frost-free date 13-Sep
Iceland Poppy 6 to 8 19-Jul 2-Aug on frost-free date 13-Sep
Rudbeckia (Black-Eyed Susan) 5 to 7 5-Jul 19-Jul on frost-free date 13-Sep
Salvia 6 to 8 5-Jul 2-Aug on frost-free date 13-Sep
Scabiosa (Pincushion Flower) 4 to 8 2-Aug 16-Aug on frost-free date 13-Sep
Scarlet Runner Bean 2 to 3 soil 60 degrees
Snapdragon 8 to 10 5-Jul 19-Jul on frost-free date 13-Sep
Statice 5 to 6 19-Jul on frost-free date 13-Sep
Stock 5 to 6 5-Jul 19-Jul on frost-free date 13-Sep
Strawflower 4 to 6 19-Jul 2-Aug on frost-free date 13-Sep
Sunflowers* 2 to 3 16-Aug 23-Aug on frost-free date 13-Sep
Sweet Pea 4 to 6 19-Jul 9-Aug 1 to 2 weeks before 30-Aug 6-Sep
Tithonia (Mexican Sunflower)* 6 9-Aug 1 week after 20-Sep
Verbena 8 to 12 21-Jun 19-Jul on frost-free date 13-Sep
Viola (Pansy) 7 to 9 7-Jun 12-Jul 1 to 2 weeks before 30-Aug 6-Sep
Yarrow 8 to 10 5-Jul 19-Jul on frost-free date 13-Sep
Xeranthemum 5 to 8 19-Jul 2-Aug 1 week after 13-Sep
Zinnia 4 23-Aug 1 week after 20-Sep
* Usually direct-sown, but can be started indoors
Note: Dates are the same from year to year, but this table requires that a year be entered for computation simplicity.

Learn More

  • Key Growing Information Pages • Index for all Crops Essential instructions for planting & growing your vegetables, fruits, flowers, herbs & farm seed.
  • Guidelines for Starting Seeds Indoors • Article Tips & troubleshooting advice for starting healthy seedlings.
  • Seed Quantity Calculator • Interactive Tool This is an interactive tool to help you determine how many seeds or plants you will need for a given amount of space.
  • Succession Planting & Harvesting Programs • Charts A set of succession-planting programs indicating which varieties of particular crops are best adapted for planting and harvesting across the span of seasonal slots. Based on multiyear trial data and curated for you by Johnny's Research Team.

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