When you shop from catalogs, it's easy to just click and buy. But when it comes to seed catalogs, there's a lot more to the process of picking out what vegetables you want to grow next year. That's why I require a yellow highlighter, Post-its and a tablet for sketches and notes. You must literally think like a designer. The reason is simple: crop rotation.
Developed by George Washington Carver to improve worn-out soils of poor Southern farmers, this system of redesigning your garden every year is essential to success. It's doubly important when growing in raised beds with high-density production, which can magnify problems that faced Carver's farmers. Crop rotation requires you to choose a vegetable for a particular space based on what grew there the year before.
This practice is essential for home gardeners who wish to reduce the chance of diseases that can decimate the food garden. It is based on the concept that plants susceptible to disease are more likely to suffer if grown in the same place year after year. Each year, new pathogens grow, and in consecutive years of infecting the same crop, their populations increase to a size that can seriously threaten plants. Change your garden each year, and the virus may never appear.
Rotation also affects nutrient availability. Where a crop requires large amounts of certain elements from the soil, that patch is becoming less fertile every year. But when different crops grow there each season, they tend to compensate for the losses naturally. In fact, if you get creative, you can actually benefit from the residue of a former crop to make your new one that much better.
For example, peas and beans can absorb atmospheric nitrogen and transfer it into the soil via special root nodules. The remnants of the plant left behind after harvest also contain the bonus of nitrogen stored in their tissues. When these are tilled into your soil, it becomes enriched with residual nitrogen. Because this is the nutrient responsible for stem and leaf growth, it's a perfect spot for leaf crops such as lettuce or kale to grow large and vigorous.
As you shop for seed, design your new garden by rotating vegetables by family. The simplest method of rotation is to just change families for each spot in the garden every year. Where you grew fennel, plant radishes. Where you grew cucumbers, grow arugula etc.
Basic vegetable families for crop rotation
Cabbage family: Arugula, broccoli, Brussels sprouts, cauliflower, kale, radishes and turnips.
Squash family: Zucchini, watermelon and cucumbers.
Nightshade family: Tomato, pepper, eggplant and potato.
Carrot family: Celery, parsley, parsnips and fennel.
Onion family: Onion, garlic, leeks and shallots.
One informal group are beets, chard and spinach. Consider lettuces one big family, as well.
The Right Seeds
Selecting seed isn't just about looking at pictures of great veggie plants and fruit. You must read the descriptions and comments for each one to be sure it will do well in your climate. The photos can be deceiving because a large, black eggplant fruit may show at the same size as a very small-fruited variety. This is why you must strive to read the entire catalog description. Sometimes it holds a key to your climatic limitations such as heat-tolerant lettuce. It may also tell northern gardeners what varieties hurry up and mature in very short growing seasons.
The details of new varieties and their place in your ever-rotating garden makes this far more time-consuming. If you're new to gardening, select just one general catalog such as Territorial Seed Co. or Abundant Life Seeds, both of which are based in Oregon.
But if you're an old hand like me, the process becomes mind-boggling as I seek the right plant for the right place with the right companions and predecessors, just as Carver would have done it long ago.