Crop Rotation

Planning Crop Rotations for Your Organic System Plan (OSP)

A Practical Guide for Organic Growers in Hawai‘i and the Tropics

Why Crop Rotation Is Required in Organic Farming

The USDA National Organic Program (NOP) requires certified producers to implement crop

rotations that:

- Maintain or improve soil organic matter

- Provide for pest and weed management

- Manage nutrient cycling

- Prevent erosion

Your OSP must demonstrate how your rotation meets these goals over time.

6 Steps to Build Your Crop Rotation Plan

1. Map Your Fields or Beds

Start by creating a simple layout of your growing area. Label each plot or bed, note the size, and record any known pest or disease issues.

Tip: Keep this map as part of your OSP and update it yearly.

2. Identify Your Main Crops by Family

Plant Family                        Common Crops in Hawai‘i                  Key Notes

Solanaceae                         Tomato, pepper, eggplant                   Rotate to avoid bacterial wilt                                                                                                        & nematodes

Cucurbitaceae.                   Cucumber, squash, bittermelon.         Manage melon fly                                                                                                        and downy mildew

Fabaceae                           Long beans, cowpea, sunn hemp        Fix nitrogen; rotate after heavy                                                                                                         feeders

Poaceae                             Corn, sorghum, sugarcane                  High biomass; good for weed                                                                                                         suppression

Brassicaceae                     Mustard, bok choy, tatsoi                      Some varieties suppress soil                                                                                                         pathogens

Asteraceae                         Lettuce, sunflower                                Quick turnover; good fillers

Apiaceae                            Cilantro, fennel                                      Pollinator-friendly; short cycle

3. Include Cover Crops and Fallow Periods

Cover crops are critical in tropical systems where continuous cropping can drain the soil.

Good tropical cover crops:

- Sunn hemp – Fast growth, nematode suppression

- Cowpea – Drought-tolerant, edible, nitrogen-fixing

- Buckwheat – Quick cover; supports pollinators

- Mustard – Biofumigant if incorporated quickly after flowering

Include at least one cover crop per rotation cycle. It shows your commitment to soil health in your OSP.

4. Rotate Crop Families Over Time

A basic rotation avoids repeating the same family in the same plot for at least two cycles. More diverse and longer rotations are better.

Season          Bed 1                               Bed 2                                          Bed 3

Spring            Tomato (Solanaceae)       Lettuce (Asteraceae)                 Cowpea (Fabacea)                     

Summer         Sunn hemp (Cover)         Pepper (Solanaceae)             Bok choy(Brassicaceae)       

Fall                 Mustard (Cover)               Bittermelon(Cucurbitaceae)        Cilantro (Apiaceae)               

5. Document for Certification

Certifiers want to see:

- A rotation schedule that includes crops, covers, and planned fallows

- A field map or layout

- An explanation of how your plan manages fertility, pests, and weeds

- Notes showing you’re rotating by plant family, not just crop type

You don’t need perfect rotation—just a clear, thoughtful plan.

6. Keep It Practical and Realistic

Even small farms with short growing seasons or high turnover can create effective rotations. If you grow lettuce year-round, for example, rotate lettuce with tatsoi or other families, and add short cover crops (like buckwheat) between plantings.

Pro Tip: Think in blocks or strips, not just entire fields. Rotating beds within a single plot can still meet organic requirements.

Common Mistakes to Avoid

❌ Growing the same crop family over and over (e.g., tomato > pepper > eggplant)

❌ Skipping cover crops

❌ Not documenting changes in your rotation plan

❌ Confusing “succession planting” with “rotation”

Need Help?

Contact your certifier or reach out to the Sustainable and Organic Agriculture Program (SOAP) at the University of Hawai‘i. CTAHR extension agents can provide templates and field-specific recommendations.