Calculate Your Garden's ROI Before You Plant

If two crops are both fighting for the same sunny 8 square feet, which one actually deserves it? Gardening doesn't need to be justified purely on financial terms, but a simple return-on-investment calculation gives you an honest comparison instead of a gut feeling. The formula is the same one used for any investment: value gained minus cost, divided by cost.

What's the ROI Formula?

ROI equals (expected harvest value minus total input cost) divided by total input cost, multiplied by 100 for a percentage. Harvest value is your expected yield multiplied by what that produce would cost at a store or farmers market. Input cost includes the seed packet, any soil amendments specific to that crop, and a reasonable estimate of water used.

Worked Example: Tomatoes

A packet of tomato seeds costs about three dollars and contains far more seeds than a home garden needs in one season, so we'll count the whole packet as the seed cost. Add roughly two dollars in amendments (compost, a stake or cage) and about one dollar in water over the season, for a total input cost of six dollars for, say, 3 plants grown from that packet. A well-tended tomato plant produces 10 to 15 pounds of fruit over a season; at 3 plants averaging 12 pounds each, that's 36 pounds total. Valuing tomatoes at four dollars a pound (a reasonable farmers-market price), harvest value is 36 times four, or 144 dollars.

ROI is (144 minus 6) divided by 6, times 100: 138 divided by 6 is 23, times 100 is 2,300 percent. Even accounting for rough estimates, tomatoes are consistently one of the highest-ROI crops a home gardener can grow.

A Lower-ROI Comparison: Sweet Corn

Corn needs a lot of space relative to its yield — typically planted at 12-inch spacing in blocks (it's wind-pollinated and needs multiple rows to pollinate well), and each stalk usually produces just 1-2 ears. A 32 square foot block might hold 32 stalks producing around 48 ears total. A packet of corn seed costs about four dollars, plus roughly three dollars in amendments and water for that block, totaling seven dollars input. Valuing each ear at about 60 cents (a common grocery or farmers-market price), harvest value is 48 times 0.6, or about 29 dollars.

ROI here is (29 minus 7) divided by 7, times 100: 22 divided by 7 is roughly 3.1, times 100 is about 310 percent. Still a positive return, but far below tomatoes' figure, and using much more space to get there — a useful data point if space, not just cost, is your limiting factor.

Accounting for Time, Not Just Cash

A purely cash-based ROI understates the real cost of high-maintenance crops. Crops requiring frequent staking, pruning, or pest monitoring (indeterminate tomatoes, for instance) cost more in time than their cash inputs suggest, while low-maintenance crops (bush beans, most root vegetables) return more time-adjusted value than the cash-only ROI implies. If time matters to your decision, add a rough hourly cost to your input total — even a conservative ten dollars an hour for an estimated 2 extra hours of tomato staking and pruning over a season adds twenty to the input side of the equation, which still leaves tomato ROI extremely high, but makes the comparison to lower-maintenance crops fairer.

Using ROI to Allocate Bed Space

Once you've calculated ROI per crop, the practical use is allocating your best, sunniest, most water-accessible bed space to your highest-ROI crops first, and pushing lower-ROI, space-hungry crops (corn, winter squash, melons) to secondary areas or skipping them if space is genuinely tight. This isn't a rule to follow blindly — some low-ROI crops are grown for taste, tradition, or self-sufficiency reasons that don't show up in a spreadsheet — but it's a useful tiebreaker when you're choosing between two crops for the same limited square footage.

A garden ROI calculation takes the same handful of numbers you already have — seed cost, amendment cost, expected yield, and market price — and turns them into one comparable figure. Running it before you plant tells you which crops earn their space back the fastest, which is useful information even if profit isn't the only reason you garden.