In a previous blog post you could think of as seed saving 101, we discussed the difference between heirlooms and hybrids in regards to seed saving. Now we take a look at specific vegetables and which are most easily saved and what planning and considerations are needed for saving seeds. Most home gardeners want to ensure that the seeds that they save will produce plants similar to, if not the same as, those from which they collected the seed.
The Genetics of Seed Saving
In order for us to discuss seed saving of specific vegetables, we first need to learn a little terminology and plant genetics. While you might think it is not the most interesting of subjects, there’s lots to be learned and it will ultimately make us better seed savers. You don’t have to delve to the level of the authors plant-geekdom (and study Mendelian genetics in radishes as your high school senior project), but a little basic knowledge will help.
Self-pollinated plants are self-fertile, which make them prime candidates for saving seeds that are “true to variety,” which means that the resulting seeds will have most of the characteristics of the parent. Self-pollination is also referred to as natural inbreeding. In some cases, such as beans and tomatoes, pollination often occurs even before the flowers fully open and the flower’s shape discourages insect pollination.
Cross-pollination can also be referred to as natural outbreeding. Cross-pollinated plants require pollen from another individual plant for successful pollination. The most common modes of pollination are wind pollination and insect pollination. These plants are harder to save seed from, since they are less likely to produce “true to variety” offspring.
Some cross-pollinated plants are perfectly happy crossing with individuals of the same variety. However, some do exhibit inbreeding depression, which refers to reduced vigor and fitness in a population that arises from inbreeding. If a species with inbreeding suppression
Hybrid vigor refers to improved vigor and fitness of individuals that rise from the crossing, or hybridization, of two genetically diverse varieties.
So What Does All this Mean?
Basically, this means that some seeds are easier to save than others. In a nutshell, here are the take-away lessons:
Legumes (beans and peas) and solanaceous crops (tomatoes, peppers, and eggplants) are by far the easiest crops to save, since they
are self-pollinated. There is the potential for cross-pollinating if you have hungry pollinators (I’ve seen bumblebees rip open bean flowers). Peppers and eggplants also have the potential for cross-pollination, so if you want to maintain a specific variety they need to be separated by at least 500 feet or have flowers bagged. Lettuce is also relatively easy to save.
Most of the other common garden vegetables have a high hybrid vigor and are natural outbreeders, meaning that they cross- pollinate readily. Members of the Cucurbitaceae family (squash, pumpkins, melons, gourds), Apiaceae family (carrots, dill, fennel), Amaryllidaceae family (onions, chives, leeks), and some members of the Brassicaceae family like the cruciferous radish exhibit little inbreeding suppression, meaning that you can easily cross a variety with itself if you isolate it from other varieties. Corn (Poaceae) and cole crops like cabbage, broccoli, and kale (Brassica oleracea) have a higher level of inbreeding depression, meaning that crosses with members of the same variety result in seeds that are less vigorous.
How do you isolate plants?
Plants that easily cross can potentially cross with other varieties in the garden or the neighbors garden. Insect pollinated plants are typically pollinated by bees, which can have a travel range of two miles or more. Home gardeners would have trouble separating their varieties that far, so it would be easier to isolate individual flowers or plants. Covering a plant with fine mesh netting or bagging flowers are popular choices.
For cucurbits, flowers have only one gender, so this is easier. Before blossoms fully open, removing male flowers and using them to pollinate female flowers is the general practice. The female flower is then wrapped in a bag until the fruit begins to form. For other plants, using netting and hand pollinating may be the option.
Of interesting note is the case of some of the cucurbits and cole crops. All of the cole crops (broccoli, cabbage, Brussels sprouts, kale, cauliflower, etc.) are all the same species and will easily cross. There are instances of crosses of broccoli and kale, sprouts and flowering cabbage and others. Likewise, many members of the cucurbit family are the same species. It is not uncommon to get crosses of pumpkins and zucchini (a puccini, anyone?) and others.