Vegetable ROI Calculator
Compare what a crop costs to grow against what the same harvest costs to buy.
Does growing vegetables save money? It depends entirely on the crop, and this calculator shows the split honestly: herbs, salad leaves and tomatoes usually beat the shop easily, while potatoes and sweet corn often cost more to grow than to buy once every input is counted. Enter a crop, your plant count, the shop price, and what you spent, and see the gross value, the net saving, and the return per square foot.
Yields per plant come from the same planning figures as the Crop Yield Calculator. Prices should be your real local shop price for the quality you actually buy, not the cheapest on the shelf.
How this is worked out
Gross value = expected yield (plants x typical yield per plant) x your shop price per pound. Net saving = gross minus the costs you enter. Return on spend = net / costs. Value per square foot uses the crop’s standard spacing to size the bed. Your time is deliberately not priced: the moment gardening counts as labour at a wage, almost nothing survives the audit, and the moment it counts as leisure, almost everything does. The calculator prices the crop, not the hobby.
Assumptions:
- Shop price should be for the quality you would actually buy. Comparing home tomatoes to the cheapest watery imports rigs the result one way; comparing to farmers market heirloom prices rigs it the other.
- Costs are the crop’s share: its seed, its share of compost and feed, its water. Fixed gear (tools, beds) amortises over years and crops, so a per-crop share is the honest treatment.
- Yield is the middle planning figure. A bad year can halve it, which the Crop Yield Calculator’s range shows.
Worked examples
1. Ten tomato plants at $3.50 per lb. About 40 lb of fruit, $140 gross, against about $12 of seed and feed share: a net saving over $120 and several dollars per square foot. Tomatoes are the classic garden money maker.
2. Fifty potato plants at $0.80 per lb. About 250 lb, $200 gross, sounds strong until seed potatoes, and the bed space for a full season enter: the net thins fast, and maincrop potatoes are famously near break-even.
3. Six basil plants at shop herb prices. Fresh basil retails like a luxury (often $15+ per lb in small packs). A few dollars of seed returns tens of dollars of pesto, the highest ROI per square foot in most gardens.
The usual winners and losers
| Usually ahead | Usually behind (grow for love) |
|---|---|
| Herbs (basil, parsley, cilantro) | Maincrop potatoes |
| Salad leaves and lettuce | Sweet corn (space hungry, cheap to buy) |
| Tomatoes, especially heirloom | Onions and storage roots |
| Beans and peas eaten fresh | Winter squash in small gardens |
| Chard, kale, zucchini | Anything you grow but do not eat |
The pattern: high shop price per pound plus high yield per square foot wins. The last row is the truest on the page: an uneaten crop has a return of exactly zero at any price.
Common mistakes
- Counting only the seed packet as cost. Compost, feed and water are real. Undercounting costs flatters every crop and teaches nothing.
- Comparing to the wrong shop price. Use the price of what you would buy instead, at your shop, this season. Organic growers compare to organic prices, fairly.
- Ignoring the bed’s season. A bed of storage onions occupies ground for seven months that could have carried two successions of higher value crops. Opportunity cost is real even when no money moves.
- Valuing glut at full price. Forty pounds of zucchini is worth forty pounds of zucchini only if someone eats it. Value what your household genuinely uses or preserves.
Putting the result to work
Run your five main crops and look at the ranking, then let it steer one bed, not the whole garden: shift space toward a winner you enjoy, keep the beloved loser on principle. Log real harvests in the Garden Harvest Value Tracker and rerun this with your own yields after a season.
Does growing this vegetable save money?
- Pick the crop and enter your plant count; the yield estimate is built in.
- Enter your real local shop price per pound for comparable quality.
- Enter this crop’s share of your seed, compost, feed and water costs.
- Read gross value, net saving, return on spend, and value per square foot.
- Compare across your main crops before deciding where next year’s space goes.
Does growing your own vegetables actually save money?
For the right crops, clearly: herbs, salads, tomatoes and soft fruit routinely return several times their costs. For cheap staples (maincrop potatoes, onions, storage squash), a careful costing often lands near break-even or behind, especially in year one when beds and tools are bought. The garden as a whole usually pays once it is established and planted toward the high value end.
Should I count my time as a cost?
Only if you would otherwise be paid for those hours. Gardeners who price their time at a wage conclude that almost no crop pays, which is true of every hobby audited as a business. The useful middle ground: count cash costs honestly, and treat time as the recreation it is, while letting ROI steer which crops get the scarce bed space.
Why are herbs such strong savers?
Price per pound. Fresh herbs retail in small, expensive packs that annualise to $10 to $30 per pound, while a herb plant costs cents of seed and yields for months. Salad leaves work the same way: high price, fast turnover, tiny footprint.
What is a good return per square foot?
Above about $2 per square foot gross is a productive bed by home garden standards; the best herb and salad beds run several times that. Under $0.50 per square foot, the bed is usually carrying a cheap staple that the shop sells for less than your inputs, or a crop nobody is eating.
How do I make the numbers honest for my garden?
Replace the planning yield with your own weighed harvest after one season, use your real shop’s prices, and allocate shared costs (a compost load, a water bill) across crops by bed area. The tracker tool exists to accumulate exactly those real figures.
Yields are the planning figures from the Crop Yield Calculator. Method (gross value vs cash costs, time excluded) follows the standard cost-benefit approach used in extension home garden economics guides.
