Crop Rotation for Vegetable Gardens: What to Plant After What
Rotation advice usually stops at “don’t plant tomatoes in the same spot two years running.” True, and not enough to act on. Two years running is not the threshold for tomatoes. Four is.
Garden.gg now tracks which plant family grew in each plot each year and warns you at planting time when you are about to repeat one too soon. The intervals are per family, because the reasons families need rotating are not the same.
Rotate families, not plants
The unit that matters is the botanical family, not the crop. Tomatoes, peppers, potatoes, and eggplant are all Solanaceae. They feed on the same nutrients and host the same soilborne diseases. Following tomatoes with peppers is barely a rotation at all.
This is the part people get wrong most often. A bed that grew tomatoes last year and peppers this year looks rotated on a garden plan and is not rotated in the soil.
The intervals Garden.gg uses
| Family | Common name | Interval | Why |
|---|---|---|---|
| Solanaceae | Nightshades | 4 years | Heavy feeders, soilborne disease pressure |
| Brassicaceae | Brassicas | 4 years | Clubroot and cabbage-family pest buildup |
| Alliaceae | Alliums | 3 years | Onion, garlic, leek |
| Apiaceae | Umbellifers | 3 years | Carrot, celery, parsley |
| Cucurbitaceae | Cucurbits | 3 years | Squash, cucumber, melon |
| Asteraceae | Composites | 2 years | Lettuce, sunflower, artichoke |
| Fabaceae | Legumes | 2 years | Nitrogen fixers, so a shorter interval is fine |
The spread from two years to four is the useful bit. Lettuce is forgiving. Brassicas are not, and clubroot is the reason: once it is in a bed it survives in the soil for years, and the way you avoid it is by not giving it a host.
Legumes get the shortest interval because they put nitrogen back rather than stripping it. That is also why the classic four-bed rotation puts legumes ahead of the heavy feeders.
What to plant after tomatoes
Tomatoes are Solanaceae, so the bed is off limits to tomatoes, peppers, potatoes, and eggplant for four years. That leaves plenty:
- Legumes (bush beans, peas) are the standard follow-on. They fix nitrogen that the tomatoes spent.
- Alliums (garlic, onions) are light feeders and fit neatly into the gap, especially garlic planted in autumn straight after the tomatoes come out.
- Brassicas work if that bed has not grown them within four years either. Check before you commit, because you can easily solve one rotation conflict by creating another.
- Leafy greens are the low-risk filler when you are out of good options.
The sequence most people land on is nightshades, then legumes, then brassicas, then roots or alliums, which gets each family back to its starting bed on roughly a four-year cycle.
The warning fires when you plant, not when you review
A rotation chart in a notebook only helps if you open the notebook. The point of putting this in the app is that the check happens at the moment you are about to make the mistake.
When you add a plant to a plot, Garden.gg looks at that plot’s family history and compares it against the interval for the family you are adding. If the same family grew there inside the window, you get a warning with the year it last grew and how long the interval is. The warning does not block you. Sometimes you have four beds and no good options, and you plant the tomatoes anyway with your eyes open.
The same check runs in the garden designer, so placement-time warnings appear while you are laying out a bed rather than after you have committed the plan.
Where the history comes from
The grid above is the case worth catching. Nightshades grew in that bed this year and three years ago, which is inside the four-year Solanaceae interval, even though the two seasons in between look like a tidy rotation.
There is no separate log to maintain, which was the design constraint. The rotation history is derived from planting records you already create: each plot plant carries a date and a plant, and each plant carries a botanical family. Group by year and you have the grid.
If you have been using Garden.gg for a season or two, your rotation history already exists. It was there the day the feature shipped.
This is also the feature that separates a garden planner from a garden drawing. A layout tool tells you where the beds are; rotation history tells you what those beds have already been asked to do. If you are still choosing between options, it is worth checking which of the free garden planners record history at all rather than just geometry.
That also means the quality of the warnings depends on the quality of your planting records. A bed where you logged three of eight crops will produce a history with holes, and a hole reads as “nothing grew here,” which is exactly the case where you want a warning and will not get one.
Small gardens and containers
Four-year rotation assumes at least four growing areas. Plenty of gardens do not have that.
If you garden in three beds, you cannot run a true four-year nightshade rotation, and no software will fix that. What you can do is know precisely when you are breaking the rule and compensate: replace more soil in that bed, be stricter about removing debris at the end of the season, and watch it harder for early blight.
Containers are the genuine escape hatch. Fresh mix each year is a perfect rotation, which is why growing tomatoes in pots year after year works when the same thing in a bed slowly stops working.
Worth knowing before you start
Rotation is a long game and the payoff is invisible. You never see the disease outbreak you prevented. What you do see, four or five years in, is that the beds you rotated kept producing while the one you kept planting tomatoes in got worse every season.
The history grid makes that visible earlier than the soil does. Open a plot, look at the family-by-year rows, and the beds you have been quietly abusing are obvious at a glance.
Crop rotation history and planting-time warnings are available on the web app, with the same warnings surfaced in the garden designer.
