Garden and DIY, cost per kilo
Cost per kilo: what home grown veg really costs
Growing your own is supposed to save money, and for two or three crops it genuinely does, by a lot. For most of the others it does not come close, and the ones people plant most enthusiastically are usually the ones that lose.
Some links on this page are affiliate links, which earn us a commission if you buy. It costs you nothing extra, and it never changes which option comes out cheapest here, because the ranking is arithmetic. How this works.
The table, and the shop price beside it
| Option | Running | Cost per kilo | Relative |
|---|---|---|---|
| Salad leaves, cut and come again£2.50 seed, about 3kg a season | £1.38 | £1.38 | |
| Courgettes£2 seed, 3kg a plant | £1.40 | £1.40 | |
| Maincrop potatoes£4 seed potatoes, 10kg | £1.64 | £1.64 | |
| Tomatoes£2.50 seed, 3kg a plant | £2.52 | £2.52 |
Those figures only mean something next to what the same kilo costs in a shop. Bagged salad is about £10 a kilo, courgettes around £2.52, vine tomatoes about £3.50, and maincrop potatoes about £1.
So salad leaves cost roughly a seventh of the shop price, courgettes about half, and tomatoes around seven tenths. Potatoes cost about 60% more to grow than to buy, which makes them the only crop here that loses money outright. The ranking of what is worth growing is almost the opposite of the ranking of what people plant.
Why salad wins by so much
Two things. Bagged salad is expensive because it is mostly water, spoils in days and has to be washed, packed and refrigerated across the whole supply chain. And a cut and come again variety is harvested repeatedly from one sowing, so a single packet of seed produces kilos rather than one crop.
Why potatoes lose
Nothing is wrong with the growing. Potatoes yield well and are easy, and a kilo still costs about £1.64 to produce against £1 in a shop. The problem is entirely on the other side: they are among the cheapest calories in any supermarket, grown at enormous scale, and there is no margin left for a domestic grower to capture. Growing potatoes is a good use of a garden and an actively bad way to save money.
Your time, which for most people is the largest input by a wide margin, and the one off cost of pots, canes, a watering can and a greenhouse if you have one. Counted properly, almost nothing in a domestic garden beats a supermarket. Counted as a hobby with an edible output, which is what it actually is, the question is only whether the ingredients cost less than the produce.
Water is the input people forget
On a meter, water is the single largest running cost of a vegetable patch. Tomatoes in growbags through a dry August can take several litres a day, and at £4.60 per cubic metre a cubic metre that adds up faster than the seed did. A water butt removes that cost entirely and is the one piece of equipment that pays for itself quickly.
The verdict
Grow salad leaves, herbs and anything expensive, perishable and picked repeatedly, because those beat the shop several times over. Grow courgettes and beans because they are generous and easy. Grow potatoes and onions only because you want to, since you will not save anything. And put a water butt in before you buy anything else.
Put your own numbers in
The consumable field is the seed, compost and water for a kilo of produce. Change the yield to match your own plot.
Cost per meal
Set the purchase price to zero for the running cost alone.
Questions
Is growing your own vegetables cheaper than buying them?
For some crops, dramatically. Salad leaves cost roughly a seventh of the shop price. For potatoes and onions there is essentially no saving, because they are already among the cheapest things in a supermarket.
What are the cheapest vegetables to grow at home?
Cut and come again salad leaves and herbs, because they are harvested repeatedly from one sowing and the shop equivalent is expensive and perishable.
How much does it cost to grow a kilo of tomatoes?
About £2.52 a kilo counting seed, compost, feed and metered water, against roughly £3.50 for supermarket vine tomatoes. Water is most of the difference.
Are potatoes worth growing?
Not for the money. They work out around £1.64 a kilo to grow once seed potatoes, compost and metered water are counted, against roughly £1 a kilo in a shop.
Does a water butt save money on a vegetable patch?
On a metered supply, yes, and it is the quickest paying piece of equipment in the garden. Water is the largest running cost of growing anything through a dry summer.
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More garden and diy costs, or read how we work these out.
Prices used on this page
- Water and sewerage, £4.60 per cubic metre. Combined volumetric water and wastewater charge, metered. Mean of three large suppliers for 2026/27: Thames Water £4.02, United Utilities £4.75, Anglian Water £5.03 per cubic metre.. Published 2026/27 household charges, Thames Water, United Utilities and Anglian Water. Checked 22 August 2026.