Crop Rotation Planner

Introduction:

Crop rotation places related crops in different beds across seasons so the same plant family is not fed by the same patch of soil every year. In a vegetable garden, that usually means tracking nightshades, brassicas, legumes, cucurbits, alliums, roots, leafy crops, and other families by bed rather than only remembering the crop name.

Plant families matter because related crops often attract similar soil-borne diseases, insects, nematodes, and nutrient demands. Tomatoes, peppers, potatoes, and eggplants are different crops, but they are all nightshades. Repeating them in one bed can keep a susceptible host available for problems that survive in soil or residue.

Rotation is especially useful in small raised-bed gardens where every space is reused. A written bed history makes the next planting decision more concrete: which bed had a recent same-family crop, which bed had a heavy feeder, and which bed had legumes that may make a better follow-on space for demanding crops.

Rotation does not make a bed safe from disease. Some problems last longer than a short schedule, and some pests use multiple hosts. Treat rotation as a planning guardrail that works best with sanitation, resistant varieties, mulch or drip watering, and notes from local extension guidance.

How to Use This Tool:

Start from the bed history you actually trust, then let the planner compare each next-season crop against those recent families and bed loads.

1. Enter Bed history with one bed per line. Use a colon after the bed name and separate seasons with a pipe, newest season first, such as Bed A: 2025 tomato, pepper | 2024 bean. The summary should update the bed count and the visual bed sequence.
2. Enter Next crops with one planned crop per line. Separate lines keep the Assignment Plan, Family Ledger, and exported records readable.
3. Set the Rotation interval from 2 to 6 seasons. Three seasons is a common starting point for home gardens; use a longer interval when a family has had blight, clubroot, wilt, nematodes, or repeated pest pressure.
4. Set Bed capacity to the number of crop lines each bed can reasonably hold. Use 1 for a single-family bed and a higher value for mixed beds, succession blocks, or compact raised-bed plans.
5. Choose Disease pressure and Planning goal. Higher disease pressure increases same-family penalties, while the goal changes the balance among disease caution, feeder balance, and compact bed use.
6. Open Advanced when you need a longer future projection or want the sequence to stay strict to the crop list instead of inserting cover-crop breaks.
7. Read Planner notes before trusting the plan. Unknown crop families, target lists that exceed capacity, and two-season intervals all need review before planting.
8. Use Assignment Plan for the recommended bed, Family Ledger for crop-family checks, Bed Guidance for per-bed follow-up, Season Sequence for future seasons, Family Conflict Heatmap for all crop-to-bed risks, Family Mix Timeline for projected family balance, and JSON when you need a structured copy of the run.

Interpreting Results:

The Assignment Plan is the first planting draft, but the Family Conflict Heatmap is the better check when you want to see alternatives. A crop can be assigned to the lowest-risk available bed while another bed still shows a high conflict for that same crop.

Do not treat a Low label as proof that the bed is safe from disease. Verify every Mixed / unknown family in the Family Ledger, and compare the heatmap against your own notes about diseased residue, flooded beds, contaminated tools, or nearby weeds that may host the same problem.

The planner assigns crops in the order listed under Next crops. If the first crop consumes the best bed, a later crop may receive a capacity warning or a weaker placement. Reordering the crop list can be a useful way to test which crop is hardest to place. The future sequence is a planning projection, so treat cover-crop rows and later-season assignments as prompts for review rather than fixed planting instructions.

Technical Details:

A rotation score starts with plant-family history. Each target crop is matched to a recognized family, feeder role, and disease-sensitivity note where the crop name is known. Each bed history line is split into seasons, with the newest season carrying the strongest effect and older seasons fading until they fall outside the selected rotation interval.

The score is not a plant pathology model. It is a deterministic planning score that gives weight to the main rotation concerns a gardener can act on before planting: repeating the same family, repeating the exact crop, following heavy feeders with more heavy feeders, using legumes before demanding crops, and crowding more crop lines into a bed than the configured capacity allows.

The Season Sequence starts with the next-season assignment, then scores later seasons against the projected bed history created by earlier planned seasons. When cover-crop breaks are allowed, the projection can insert a break row if every listed crop would be a high-risk repeat for that bed. The Family Mix Timeline chart counts the crop families by projected season so repeated dominance is visible before you export the plan.

Formula Core:

For each crop-to-bed pair, the base score is clamped to a 0 to 100 range and rounded to a whole number for display.

Here N is the selected rotation interval, i is the season index with 0 as the newest season, r is the recency weight, F is same-family pressure, C is exact-crop pressure, H is recent heavy-feeder pressure, D is the disease-sensitive family add-on, L is the legume credit for a heavy feeder, and S is the displayed score.

Disease pressure changes the family and exact-crop weights. Low pressure reduces family and exact-crop pressure, moderate pressure leaves them unchanged, and high pressure increases them. The planning goal also changes the balance: disease caution raises the family weight, fertility planning raises the heavy-feeder weight, and compact planning reduces the penalty for putting more crop lines into one bed.

Assignment uses the base score plus bed-load adjustments. Each crop is placed into the lowest-scoring candidate bed available at that point in the list. Existing load adds a compactness penalty, a bed that is already at capacity receives a larger spillover penalty, and a small mixed-family penalty discourages unnecessary mixing when another bed is close. This makes the output practical for raised beds, but it is not a global optimization across every possible crop order.

A simple mechanism walkthrough shows how the pieces combine. With a 3 season interval, a tomato planned for a bed that had tomato in the newest season receives full same-family pressure, exact-crop pressure, and the disease-sensitive add-on, so the score can cross into High. The same tomato planned after a recent legume bed has no same-family hit and may receive a legume credit, so the score can remain Low even though compost and cleanup may still be useful.

Limitations and Privacy:

The result is a garden planning estimate. It does not diagnose disease, identify pathogens, test soil, or know which weeds and crop debris stayed in the bed. Local extension advice, soil tests, resistant varieties, sanitation, and careful watering still matter when disease pressure is real.

• The crop-family list is intentionally limited. If Planner notes reports an unknown family, check the crop name and verify the family before using the risk label.
• A 3 to 4 season break is a common home-garden target, but some long-lived soil problems may need longer breaks or non-rotation controls.
• Capacity warnings are practical bed-space warnings, not crop-spacing advice. Confirm real spacing, trellis needs, airflow, and harvest access before planting.
• The bed and crop text is evaluated in the browser for the planning run. Treat copied JSON, downloads, and any shared browser address as your own records, and remove private site notes before sharing them.

Worked Examples:

FAQ:

Glossary:

Plant family

A botanical relationship group used to spot crops that may share pests, diseases, and nutrient patterns.

Rotation interval

The number of recent seasons checked before repeating the same family in a bed.

Disease pressure

The selected caution level that increases or reduces penalties for repeated family and crop history.

Heavy feeder

A crop group that tends to draw heavily on soil fertility and can create a watch note after another heavy-feeder season.

Nitrogen fixer

A legume role that can make a bed a better follow-on candidate for a heavy feeder.

Bed capacity

The configured number of planned crop lines each bed can reasonably hold.

Season Sequence

The result table that projects each bed through the selected future horizon after the next-season assignment.

Family Mix Timeline

The chart view that counts planned crop families by projected season so overused families are easier to spot.

Family Conflict Heatmap

The result view that compares every next crop against every bed before the final assignment is chosen.

References:

• Preventing plant diseases in the garden, University of Minnesota Extension, reviewed 2021.
• Raised bed gardens, University of Minnesota Extension, reviewed 2026.
• Rotating crops for a more resilient garden, Illinois Extension, February 28, 2025.
• Disease Prevention in Home Vegetable Gardens, University of Missouri Extension, reviewed March 2026.
• Organic Vegetable Gardening Techniques, University of Missouri Extension.