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Planting Calculators & Tools
Use Johnny's interactive planning tools and calculators to help with planning and scheduling your growing season. From calculating how much seed you'll need and when to plant, replant, and harvest, our calculators can help you streamline your operation to become more productive, profitable, and enjoyable. Just getting started? You may want to begin with our article, Planning & Plotting Your Market (or Backyard) Garden
Seed Quantity & Yield
- 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. The following 2 charts also serve as reference.
Planting Date Calculators & Spreadsheets
- Seed-Starting Date Calculator for Starting Seeds Indoors Interactive Tool
This tool figures the dates for starting seedlings indoors and for safely planting particular early crops outside, based on the frost-free date that you specify. - Target Harvest Date Calculator Workbook (XLSX)
Use this tool to coordinate production of one of more crops for harvesting by a particular user-defined target date or otherwise important event. Determine seeding date relative to a specific harvest date.
Succession Planting Spreadsheets & Charts
- Succession-Planting Calculator Workbook (XLSX)
This spreadsheet calculator allows you to input the date of your first planting of each crop, then it calculates the dates for later plantings. It also allows you to input your first fall frost date, counting back the appropriate number of days to determine the last date to plant and still get a crop before frost. - Fall-Harvest Planting Calculator Workbook (XLSX)
This spreadsheet calculator works backward from your first fall frost date, to determine the best date on which to start seeds for crops that will mature successfully as summer warmth and light wane into the fall. - Succession Planting Interval Charts for Vegetables Charts
Follow these general guidelines for succession-planting vegetable crops at intervals of 7 days, 10 days, 14 days, 21 days, and 30 days. - Succession Planting Interval Charts for Flowers Charts
Follow these general guidelines for succession-planting flower crops at 7-day and 14-day intervals. - Succession Planting Interval Charts for Herbs Charts
Follow these general guidelines for succession-planting herb crops at 7-day and 14-day intervals. - 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.
Season Extension Charts & Calculators
- Winter Harvest Planting Dates Chart
Calculate fall planting dates for winter-harvest crops. - Overwintering Planting Dates Chart
Calculate planting dates for overwintered crops for an early spring harvest. - Overwinter Flower Trials • Seeding Date Calculator Workbook (XLSX)
On entering your last 10-hour day of the year, this calculator displays a range for your earliest and latest seeding dates as well as the seedling transplant date, for each of 25 flower crops suitable for overwintering. Based on the results of Johnny's Multiyear Overwinter Flower Trials. - Bloom Date & Chilling Date for Forced Tulips • Date Calculator Workbook (XLSX)
Use this spreadsheet calculator to determine the start and end dates for chilling and estimated bloom dates by tulip variety for forced tulip production.