Basic Principles of Breeding Heirloom Vegetables



Tips for raising vigorous seeds, whether your goal is to preserve a variety or to create a locally adapted strain.

Basic Principles of Breeding Heirloom Vegetables

Basic Principles of Breeding Heirloom Vegetables

The world of heirloom vegetables is a fascinating one, full of unique colors and traditional flavors.

While saving seeds from heirloom plants can be as simple as collecting whatever is available, best results will be obtained from attention to good breeding practices. Proper selection of breeding stock will ensure generations of vigorous seeds that produce delicious harvests.

What’s Your Goal?

There are two main purposes for breeding heirloom vegetables:

  • To preserve a rare or historic plant variety.
  • To raise plants adapted to your unique situation.

It is important to determine your purpose right at the beginning, because each objective requires a different focus when selecting the plants that will produce the next generation of seed. Preserving a variety requires a conservative approach, taking steps to avoid altering the gene pool in any way. Raising adapted vegetable genetics requires a progressive approach, actively shaping the gene pool to meet your needs.

Preserving a Variety

If variety conservation is your goal, then your breeding philosophy must be to avoid altering the historic gene pool in any way. This can be surprisingly challenging, as there are many ways to inadvertently shift the genetics. The tendency of this shift will be toward plants that are adapted to your specific gardening conditions in the specific year that the parent plants were grown. While this adaptation process has advantages, it also has disadvantages—you may need different genetics in a different year, or you may wish to share seeds with gardeners with different growing conditions. Either way, a broad gene pool with a great deal of variation is desired for conservation purposes.

To maintain a broad genetic base, you must start by choosing a variety already well adapted to your conditions. A variety not suited to your environment or gardening practices will likely have a high mortality rate. The surviving plants will only be those with adapted genetics, thus altering the gene pool.

You will need to grow many plants in each generation to ensure a broad genetic base and avoid inbreeding problems. You may only need five plants for a healthy generation of self-pollinating species such as peppers, while tricky species prone to inbreeding like corn may require you to grow over 100 plants. Each plant must be nurtured to maturity and allowed to produce a crop of seeds if at all possible.

Culling must be kept to a bare minimum. Only cull the following plants:

  • Those that are clearly diseased and thus will likely spread infection to other plants.
  • Those that are not true to type and thus not representative examples of the variety.

To avoid inadvertently giving preference to some plants, equal amounts of seed should be saved from each individual plant.

Raising Adapted Plant Genetics

Heirloom vegetable varieties can easily be selected for better performance in your garden with no need for hybridizing. All you have to do is create your own strain within the variety.

A good way to start when developing a locally adapted strain is by making a list of characteristics that you want to see in your plants (for best results, start with only two or three traits max). Such characteristics might include:

  • Drought tolerance.
  • Pest or disease resistance.
  • Resistance to bolting.
  • High yields.
  • Uniform fruits.
  • Excellent flavor.

When choosing the parent plants, cull those that do not display the characteristics that you desire. Deliberately expose your plants to climatic vagaries to allow nature to sort out the best low-maintenance plant genetics (just be sure to allow them to recover in time to produce a healthy seed crop). Mark the most adapted plants with pieces of ribbon so that you can identify them when it is time to collect the seed. Favor exceptional plants when saving seeds—well-adapted plants will typically produce the most seed anyway.

However, be careful not to narrow your vegetable gene pool too quickly, or the plants may start to lose vigor due to inbreeding. If you select too aggressively, you may accidentally make your plants less adapted to years with unusual climatic conditions. There are several easy ways to keep the gene pool broad and healthy without sacrificing your objectives:

  • Start with a variety that has a great deal of genetic variation to begin with.
  • Raise numerous parent plants in each generation.
  • Include a few seeds from the original strain in every planting.

A Few Final Hints

To keep your motivation levels high, start simple and give yourself some leeway to learn about plant selection and seed saving. Begin with only one or two varieties, and choose those from species that are easy to work with. Plants that mostly self-pollinate are ideal. Some good plants to practice with include:

Keep good records. Mark your rows and label your bags and envelopes of seeds. This is particularly important if you grow more than one variety of the same species.

Most importantly, only grow plants that you enjoy. If you don’t like eating beets, don’t grow beets. If indeterminate tomatoes and pole beans are just too much hassle for you, it won’t matter that they have superior flavor. Trade them in for determinate tomatoes and bush beans—there are still plenty of tasty varieties of those plants out there!

The Family Garden Journal