2011-12-01 / Editorial

The Island Garden

Rotate your crops for best yields


BY ROGER MARSHALL BY ROGER MARSHALL Do you have a drawing of your garden showing where you planted all your vegetables this year? If not, I suggest that you make one right now before you forget. By having a drawing of your garden, it will also help you plan where you want to grow vegetables next season and what seeds or plants that you might want to buy now that seed catalogs are arriving.

Why make a drawing? If you have a drawing showing where everything was planted, you can rotate your crops. No, that doesn’t mean you turn the cabbages around so that a different side faces the sun each day. It means that each year you grow different vegetables in the same garden bed to ensure that nutrients are not exhausted and diseases do not stay in the soil. Several university studies indicate that crop rotation leads to greatly increased yields, lower disease levels and better soil structure. It can also improve soil drainage and give you a far better looking vegetable garden.

Vegetables have different nutrient requirements and many vegetables harbor pathogens that can stay in the soil to attack next year’s crops. For example, if you grew corn last year, the corn might have absorbed a lot of the nitrogen in the immediate area around each plant. If you plan on growing corn in the same spot next year, you’ll probably be happy with your yields, but if you continue to grow corn in the same place, eventually there will be few nutrients left and your corn will be stunted with poor yields. If you grow heavy feeders such as corn and cabbage, you might want to grow peas or beans in that spot next year to help to fix nitrogen in the soil and replenish nutrients used by heavy feeders.

There are several methods of crop rotation. One suggestion is to divide your garden into three parts and plant corn, squash, pumpkins, tomatoes, peppers, eggplants and potatoes on one area, brassicas (cauliflower, cabbage, broccoli and lettuce) in another, and legumes (beans and peas) in another. Onions or members of the onion family can be planted in any of the areas.

Frankly, I prefer to divide the garden into four, with tomatoes, peppers and eggplants split into their own grouping. This puts the heavy feeders (corn and squash) on one patch, followed by legumes, followed by brassicas, and then by tomatoes and peppers. However, even this method has its drawbacks. It is said that tomato diseases can last in the soil for up to 20 years, which suggest that tomatoes need to have their own patch almost every year.

Because corn and squash are usually finished about two-thirds through the season, and garlic and onions are pulled around the middle of the summer, you can often grow a second crop in the same year. Unfortunately, this leads to complications when you are planning your crop rotations and you need to be careful where everything is located.

As an example, the garlic was harvested this year in June and turnips were planted in that area. When the turnips were harvested in October, winter rye was planted to help maintain the nutrient level over the winter and to prevent soil runoff. In spring the winter rye can be dug in to give the soil a nutrient boost. Dig it in about three to four weeks before you plant your brassicas for maximum nitrogen boost.

However, when you are growing so intensively, you should also maintain a compost pile and spread compost on your garden each spring. Even rotational cropping and winter rye cannot replace all the nutrients that plants take up and adding compost or manure helps improve soil structure, retains moisture, and raises nutrient levels. Over the winter you should also check your garden’s pH levels to see if you need to add lime, then manure, and compost in spring.

So start now – make a drawing of your garden showing where you grew various rows of plants, and then wait for the seed catalogs to arrive so that you can pick next year’s winners.

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