The default prices in the Garden ROI app come from USDA Agricultural Marketing Service national average data. A tomato is $1.78/lb. Basil is $15.50/lb. Lettuce is $1.45/lb. These numbers are accurate as national medians, but they are not your numbers.
If you live in San Francisco or New York, your grocery store charges 30-50% more than the national average for the same produce. If you are in a small town in the rural Midwest, it might be less. The ROI calculation is only as accurate as the prices you put into it, and “national average” is a starting point, not an answer.
Here are three ways to find the actual prices in your market.
Method 1: USDA AMS regional market reports
The USDA Agricultural Marketing Service publishes weekly wholesale and retail price reports broken down by region - not national averages, but prices at terminal markets in specific cities. These are free, updated weekly, and available at ams.usda.gov/market-news.
The most useful reports for home gardeners:
- Specialty Crops under “Fruits and Vegetables” - covers herbs, specialty greens, and items like cherry tomatoes by variety and origin
- Fruit and Vegetable terminal market reports - Boston, Chicago, Dallas, Los Angeles, New York, Philadelphia, Seattle, and others
You want the retail prices, not the wholesale prices. The terminal market reports show what is moving through distribution channels. For retail, look for the “Retail Advertised Prices” reports, which track actual grocery store pricing by region.
This is the same data source the app uses for national defaults. When you find the regional report for your area, you will see whether your market runs above or below the national line.
Method 2: Your grocery store receipt
The most accurate price for your ROI calculation is the price at the store you would actually shop at. Photograph or log the per-lb price the next time you buy produce. One trip through the produce section with your phone covers most crops.
A few things to track:
- Price per pound, not price per item. Tomatoes sold “3 for $5” need to be converted: weigh three, divide $5 by the total weight.
- Organic vs. conventional. If you grow without pesticides, compare to organic retail prices. Organic basil runs $2-4/oz at most grocery stores - that is $32-64/lb, versus $15/lb conventional. The organic comparison changes the math significantly.
- Seasonal pricing. Tomatoes in August cost less than tomatoes in February. If you are growing summer crops, compare to summer retail prices - not the off-season premium you see in winter.
The app lets you override the default price per crop. Once you have your local number, enter it. The ROI figures update immediately.
Method 3: Farmers market premium
Farmers market prices for the same crop routinely run 2-3x the grocery store price. This matters if you are thinking about what you could sell, but it also matters as a comparison point for what you are growing.
If organic cherry tomatoes at your local farmers market are $6/pint (roughly 0.75 lb), that is $8/lb - more than four times the USDA national average of $1.78/lb. Growing cherry tomatoes to substitute for that market purchase returns $8/lb in avoided cost, not $1.78.
You do not need to sell your produce for the market price to matter. Every pound you grow is a pound you did not buy - and the question is what you would have paid for it.
The honest caveat: most gardeners buy both market and grocery produce depending on the week. A blended price is fine. The point is to use a number that reflects your actual buying habits, not a national median that may not match your market at all.
What to do with your local price
Once you have a price per pound for a crop - from your receipt, from the USDA AMS regional report, or from your farmers market - go into the app and update that crop’s default price. The break-even calculator and ROI estimates will recalculate against your actual numbers.
A crop that looks marginal at national average prices can look excellent at local prices. Garlic is a clear example: conventional softneck garlic averages $3-5/lb nationally (USDA ERS, 2023), but domestic hardneck at specialty grocers and farmers markets runs $8-14/lb. Knowing your local market determines whether the ROI case for garlic is good or exceptional.
Related reading: First 3 Years of Garden ROI: Year-by-Year - how local price accuracy compounds over multi-year planning