Sorting Out Seed Types and Terminology
With so many seed types out there, it’s sometimes hard to distinguish which type of seed you’re actually buying. Our grow expert, Grubbycup, takes a closer look at seed types and how they differ.
There are many terms used to describe different types of seeds, here are some of the most popular you’ll come across.
Annual plants complete their life cycle within a year. Many annuals are garden vegetables as they are planted, grown, and harvested within a single season. Seeds from these annuals are easy to collect, although it may require the sacrifice of allowing a few plants to progress past their normal harvest peak to ensure maturity and viability. Saving seeds from garden annuals with mature seeds at normal harvest, such as peppers, tomatoes, melons, and squash, is particularly popular. Sometimes the same plants are grown as annuals in colder climates, and as perennials in milder climates.
Coated seeds have an artificial covering that adds a beneficial factor to the seed’s exterior coat. Polymers are often used to bind the additives to the seed. Some coated seeds have a fertilizer component that sloughs off as the seed sprouts. This supplies the new sproutwith additional nutrition during initial root development. Small seeds tend to benefit more from nutrient coating than large seeds as they have smaller roots at sprouting. Another type of coating is used with clover and other legume seeds that includes a rhizobia inoculant to ensure nitrogen-fixing bacteria is present near the sprouted plant. Other coatings include colors for visibility and ease of identification or to minimize seed dust.
Genetically Modified Organisms (GMO)
Genetically modified organisms have had sections of their DNA replaced with DNA from an otherwise incompatible life form. Examples include plants with genes from bacteria, viruses, insects, or animals inserted into their genetic code. This is done to introduce traits not available through standard breeding practices, and to create patentable life that can be owned by the proprietary corporation. For example, Roundup Ready crops are those that have been genetically modified with a gene from bacteria called Agrobacteria allowing for resistance to glyphosate (Roundup). One concern is the use of GMOs can introduce new genetic pressures in associated plants, as in the case of glyphosate-resistant superweeds which have developed in response. Another concern is the proliferation of GMO crops creates genetic bottlenecks and comes with many of the same drawbacks as clone-only monoculture plants such as the Gros Michel bananas, where a previously undiscovered pathogen susceptibility to Panama disease resulted in catastrophic blight.
Hybrid (F1, filial 1)
The crossing of two distinct inbred lines produce seeds that are similar to each other. For example: If a pea plant that is true breeding (homozygous) for purple flowers (dominant trait) is crossed with a true-breeding pea plant for white flowers (recessive trait), then the first generation (F1-Hybrid, heterozygous) will display purple flowers. However, if members of the F1 generation are crossed together (the F2 generation), they will produce some plants with purple flowers and some with white flowers (approximately 75 per cent purple and 25 per cent white). Since the results will be mixed, it is commonly advised not to save seeds from hybrids if regularity in the offspring is desired (if regularity is not an issue, seeds from hybrids can be grown out and the variety of resulting plants observed).
A line is said to be improved when an otherwise open-pollinated variety is further selected from and desirous traits are emphasized. If a seed line has been noticeably enhanced by further inbreeding, it is described as improved. Clover bred to be shorter for use in lawns is an example of an improved clover. Another example would be when the process of seed saving over several years enhances a variety’s suitability for a given environment.
Open-pollinated seeds are from a true-breeding population for enough traits, so the offspring will resemble both the parents and each other. Part of the value of growing heirloom varieties in home gardens is crops that weren’t selected primarily for their commercial properties, such as shipping suitability or shelf life, can be explored and enjoyed. Some of the best tasting tomatoes are unsuitable for storage and shipping but can be grown in a backyard garden where they can be eaten shortly after picking. Open-pollinated plants are considered to be the best seeds for seed saving from one season to the next.
Certified organic seeds have been collected from plants grown under the USDA's National Organic Program. There are specific guidelines as to how the seeds may be collected, stored, and handled before packaging. Seeds that are GMO are not eligible for organic certification.
Pelleted seeds are mixed with an inert material for ease in handling. This is commonly done with small seeds to facilitate planting. The resulting larger size is easier for planting machinery and is less prone to wind drift.
Perennial plants take more than one season to complete their life cycle. Some flowers don’t produce blooms until the second year after they’ve been planted, and some fruit trees can take several years before fruit production starts.
Some seeds (including many Northern woody perennials) need to go through a process of stratification before germination. In nature, these seeds are exposed to cold wet conditions during winter which softens the seat coat and allows for germination in the spring when conditions improve. While commercially bought seeds generally have this emulated by having spent time in a moist refrigerated area before packaging and sale, home gardeners may have to take special measures by either leaving seeds exposed to outdoor conditions or simulating winter with a refrigerator before using certain garden seeds.
Treated seeds have been exposed to an antifungal agent, pesticide, preservative, or other treatment to aid in sprout survival.
Understanding common terms associated with seeds can be helpful in planning gardens and deciphering seed packet descriptions. In general, if the seeds aren’t marked with a particular attribute, then it either doesn’t apply or is considered standard (i.e. coated seeds are marked coated, but uncoated seeds usually bear no mention of the topic, and seeds needing stratification usually are assumed to be stratified-marked or not). These terms are useful to gardeners who save seeds for planting the following year.