By Gail Cocker, Master Gardener, SCMG
Spring is on the horizon and you are keen to get out into your vegetable garden, seed packets and transplants in hand. Do you make a plan for your garden or are you action oriented and just start sowing? Do you bother to record what you planted where the year before or do you just ‘dive in’?
Rotating your crops from year to year can seem like a lot of record keeping and a boring organizational step for many gardeners who want to “get in the dirt”. However, with a little bit of planning you may find you produce a more bountiful and healthier harvest by following a crop rotation program.
What is Crop Rotation?
Simply put, crop rotation is the practice of not planting the same crops in the same spot year after year.
It is an organized approach to planning your garden so that you change the location of crops following a set pattern.
First and foremost, rotating your crops improves your soil’s fertility. Different plants use different soil nutrients at different rates. If you keep planting the same crop in the same spot year after year than the nutrients will get depleted faster than he soil can re-produce them. From year to year that particular crop health will lessen.
Beyond the need to mange your garden soil’s fertility, crop rotation helps reduce plant pests and diseases. If you plant the same vegetables in the same spot every year you can be sure that the insects will be back again next summer to much on their favorites. However, if you mix things up with a little crop rotation, garden pests won’t know where the party is being held next year.
Crop rotation can be an important practice for preventing some diseases caused by fungi and bacteria. Giving the soil a break for 3 years by planting the space with non-susceptible crops usually allows enough time for the infected plant material in the soil to completely decompose and the soil-borne pathogens typically die off. This is particularly significant for tomatoes and potatoes, (plants in the same family), which are often stricken by soil borne pathogens. Ideally you should wait 3-5 years before re-planting these crops in the same area.
Lastly, maintaining a good crop rotation can assist you with your long-term weed management as it prevents the establishment of weeds adapted to a certain cropping system.
How do you do it?
The number of crops you want to grow and the size of your garden dictates the best type of crop rotation plan for you.
The simplest model is a 3 year rotation based on the plant part harvested. The most elaborate model groups your crops by plant family and you wait at least 3 years before replanting a bed with a crop from the same botanical family , (there are 11, although 9 is usually sufficient, see note below*). Although complicated, rotating by family is the most effective way to reduce the impact of pests and diseases.
Simple 3 year Harvest rotation plan
- Group your crops by the part of the plant harvested; leaves/fruits (or flowers)/roots. In year one plant leafy vegetables such as lettuce in the bed followed the next year by tomatoes and in year 3 plant beets and carrots in that space. In year 4 you can start again with leafy crops.
- This type of rotation helps maintain balanced soil over time because each group of crops draws nutrients in different proportions from the soil.
- Remember though that although potatoes are a “root” by this model, they are in the same family as tomatoes and attract the same diseases, so consider potatoes as a “fruit” crop
Four year Rotation Plan: Fruit to Leaf to Legume to Root
- This rotation plan also considers the nutrient draw that crops make on the soil. Crops are rated as heavy feeders, moderate feeders or light feeders.
- In this model you begin with a heavy feeder, plant a moderate feeder the second year and a light feeder the year after. So in year 1 you plant squash or corn in the bed, in year 2 you plant rows of spinach and kale, followed in year 3 by beans and finally onions and leeks in the 4th
- By segregating the legume family, (peas and beans) as a separate category, you actually use these “nitrogen fixing plants” to recharge the soil by transforming nitrogen found in the air in soil into a form that plants can use.
- Fruits and Leaf are both considered heavy feeders while the root crops are thought of as light feeders.
- The back to back planting of heavy feeders will deplete your soil nutrient levels so it is wise to add back a thick layer of compost of leaf mould in autumn before planting your fruit crop the next year. Similarly, in the spring, before you plant out your brassicas or leafy vegetables add manure or compost 3 weeks before planting.
If you have the space, add in a cover crop
- Add a cover crop, or green manure crop, into your rotation to really give your soil a rest. Plant a cover crop , (buckwheat, field peas, red clover , vetch, or oats) in year 4 or 5 and then follow it with your year 1 crop. The green manure crop will recharge the soil nutrient supply and encourage the soil mico-organisms to flourish.
Creative Ways to Achieve Crop Rotation
Rotate to Containers
- Every 3rd year plant your tomatoes, or potatoes, in pots to free up garden space
- Plant herbs in containers
- Another option for limited space is to rotate a pest troubled crop out of the vegetable patch into a sunny flower garden
Skip a Year
- If pests have become a serious problem, sometimes the best idea is to simply not grow a crop for a year. If Without a host plant the population of squash bugs or flea beetles etc. will die out.
While the snow is still on the ground, why not spend some time mapping out your garden layout? Start by listing all the crops you’d like to grow in your garden this year. Now figure out approximately how much space you need to devote to each. Sort the crops into groups of fruit, leaf, root and if space permits, legume. Layout the space for each group. Make a note of what types of crops will follow in this space next year. Your garden will benefit and you will find an improved harvest in the future.
Squash: cucumbers, gourds, melons, pumpkins, squash, watermelon, zucchini
Nightshade or Tomato: eggplant, peppers, potatoes, tomatoes
Brassica (or Cabbage): cabbages, arugula, broccoli, Brussels sprouts, cauliflower, collards, kale, kohlrabi, mustard, radish, turnips, rutabagas
Legume: Beans, peas
Onion: garlic, leeks, onions, shallots
Lettuce: artichoke, endive, lettuce, kale, radicchio
Goosefoot/Beet: Beets, spinach, swiss chard
Carrots: carrots, celery, parsnips