GardenKitHow it works
The target plant count comes from the same rectangular spacing grid used by the plant-spacing calculator. Divide the target by the germination fraction, then add your reserve before rounding to whole seeds. Next round the seed count up to whole packets. This is a planning expectation, not a guarantee: germination varies with conditions, and some seedlings may not survive transplanting or later growth. It does not model seeds per gram, broadcast lawn seeding, multiple seeds per station or crop-specific thinning. Choose the germination and reserve values from the packet and your growing plan.
Formula
Seeds = round up (plant positions ÷ (germination/100) × (1 + reserve/100)). Packets = round up (seeds ÷ seeds per packet).
Example
For 40 plant positions, 85% germination and 10% reserve, plan to sow 52 seeds. At 50 seeds per packet, buy two packets, containing 100 seeds in total. At 3 per packet the purchase estimate is 6. Sowing all purchased seeds would be a different plan; the required count and purchased count are shown separately.
Assumptions and limitations
Use product labels and local growing guidance. Defaults are examples. Assumptions use your inputs, not live weather or crop-specific prescriptions. Volume estimates exclude delivery and tax. Bag quantities round up.
Sources and assumptions
University of Minnesota Extension · Garden bed · University of Minnesota Extension · Water
Frequently asked questions
Are my garden measurements uploaded?
No. The tools save your current bed and settings in this browser. Clear this site’s data to remove them.
Does switching units change the result?
No. Dimensions stay in metres internally. Imperial views use feet and inches, cubic feet for bags and US gallons for water.
Are the defaults recommendations for my plants?
No. They are worked examples. Use product labels, crop requirements, soil moisture and local growing guidance.