Vegetable gardening is very popular these days, and even more so since the COVID outbreak.    Anyone new to this hobby is quick to hear some terms being thrown around when describing different types of vegetables. Knowing the meaning of these terms gives prospective gardeners some key information that helps them pick varieties of vegetables most suited to their needs. All living creatures, known to man, are classified according to species and genus. So for instance, all tomatoes are classified as Solanum lycospersicum.  

To start off, I already used the term “variety”. This term is used rather loosely in horticulture and is incorrectly interchanged with “cultivar”. Both refer to the differences in the species of plant you have chosen. Varieties refer to naturally occurring deviations from the original species. They typically come true to seed. Cultivars have been purposely cross-bred from two or more different species. Plants must be either vegetatively propagated or started from hybrid seed each year. These varieties or cultivars have names and are associated with specific characteristics.  For example when I say “Sweet Millions” tomatoes, a person familiar with this cultivar knows that they are cherry tomatoes, indeterminate, very flavorful, and highly productive. For the sake of this article, I will stick with tomato examples, but these terms could apply to many vegetable species and cultivars. 

Tomato ‘Sweet Millions’. Photo by dmp2018

Our tomato plants contain both male and female flower parts. Because of this, they are easily pollinated by wind or bees. This is problematic for greenhouse tomato growers, so they will hand pollinate the tomatoes with paint brushes or even special electronic devices that shake the flower to accomplish pollination. Fortunately for us outdoor gardeners, we do not need to do anything special for pollination to occur. 

Two different types of vegetable pollinator wands for use in the greenhouse setting. Photo by mrl2021.

Probably the best place to start is talking about “open pollination.” This is essentially how Mother Nature does things. There is a large population of organisms that have genes for individual traits, or characteristics. If we stick with our tomato example, think of: size, color, growth habit, disease resistance, plant height, etc. In my example, the population of tomatoes living in the wild in a certain area would have a lot of genetic diversity. As we all have experienced, the weather can vary from year to year. Genetic diversity in the population is nature’s way of ensuring that some organisms will survive and reproduce. Likewise, different parts of the country (or the world) will have different weather, climates, and microclimates.  Certain traits or characteristics are an advantage or a disadvantage depending on where you are living.  Over time, a population of tomatoes will see an increase in the genes that help it survive in the local environments. These would be considered different varieties of tomatoes.   

Some growers like to have open pollinated plants. They see which tomatoes produce the best and then save seeds from those plants to be planted the following year. In this way, the gardener is essentially developing a variety of tomato that is perfectly suited to living, growing, and even thriving in that particular area of the world. In addition, the gardener may also select for certain traits he or she prefers, like low acid, yellow tomatoes for example. Over time, the gardener may select and replant only the seeds of the plants that conform to certain pre-determined criteria.  Eventually the plants will breed true, or have the same set of characteristics, year to year.

This little cherry tomato was not planted by the gardener. It came from last year’s hybrid varieties. If desired, seeds could be saved and a new variety selected over time. Photo by mrl2020.

For the next term, I would like you to think of a young man that proposes to his girlfriend and while doing so presents her with his Grandma’s diamond ring. This piece of jewelry was passed down through the generations in his family. We call this ring an heirloom. Well there can be heirloom plants as well. These are varieties that have a specific set of characteristics and have a documented history. One of my favorite examples is the Brandywine tomato. This variety dates back to the late 1800s, and is noted for its exceptionally unique flavor, reddish pink coloration, and potato-shaped leaves. Heirloom varieties are open pollinated as well. What sets them apart from regular open-pollinated varieties is their documented history of being passed down through the generations, by name, with those specific characteristics. Many people fall in love with the idea of planting something so “valuable” that has been passed down through the generations.  Unfortunately, many of the heirlooms are not disease resistant and have a hard time growing in our modern world. Growing in containers with soilless media or in new planting areas are best suited to heirloom plantings. As long as there was no cross pollination (closely planted varieties of the same plant or active bees could do this), you should be able to save the seeds and get the same variety the following year.

Heirloom tomato, ‘Cuore di Bue’ Photo by dmp2019

This brings us to the next name to learn, and that is “hybrid”. A hybrid variety is formed by crossing two specific parent types. These parent varieties are usually kept secret. This produces a certain set of characteristics in the offspring. Examples include ‘Big Beef Hybrid’, ‘Better Boy Hybrid’, ‘Lemon Boy Hybrid’, etc. These can be particularly useful, and have specific qualities for which a gardener is looking. A gardener must pick carefully, as some of these hybrids are selected to transport well, delay ripening, or some other trait desirable for commercial production but not the fresh picked home-grown experience. The big advantage of hybrid tomatoes is the disease resistance they can have, although not all hybrids have the same disease resistance profile. I prefer to patronize companies that describe the disease resistant characteristics of the hybrid seeds I am purchasing. The downside to growing hybrids is that if you save the seeds and replant the following year, they will look nothing like the parent plants! They essentially would be like starting with an open pollinated version year one and it could take many, many years to get a tomato that breeds true (has a consistent set of characteristics from generation to generation).  Some people do not like to use hybrid seed as it forces you to buy new seed from the seed company each year. Others believe it is a small price to pay for disease resistance and known characteristics one can count on. Knowing the specific attributes of the plants before planting can be highly important for the home gardener and commercial grower alike.

Tomatoes that are ideal for transport to retail settings have different characteristics selected for compared to the home garden varieties. Photo by mrl2021

The next type of tomatoes has been used by commercial field and greenhouse growers for years.  Within the past ten years or so they made their way into the retail markets. These are “grafted” tomatoes. The grafting process goes back for many thousands of years for various reasons depending on the crop species. For tomatoes, simply put, we cut the above ground portion off and stick it onto the root stock of another variety. This can be done with our heirlooms. The top portion retains the qualities of taste, color, and style while the bottom root portion of a different variety, attribute’s resistance to many soil borne pathogens. The reason these have not really caught on too well in the retail market is the price. There is a lot of labor involved with this process, and for every one plant you sell you actually have to grow two plants (one for the top, and one for the roots). While a packet of thirty seeds or four plants may sell for three or four dollars, a single grafted plant of the same variety can sell anywhere from eight to thirteen dollars.  This is assuming you can find what you are looking for locally as none of those prices include shipping!

The final topic I wanted to cover was Genetically Modified Organisms, or GMOs.  These organisms have had their genetic material altered in a way that is not natural. Normally, we get new gene combinations through egg and sperm formation and the resultant reproductive event that follows. With genetic modification, genes can be altered, removed, or added in. Scientists can also cross genes from different species of plants or animals. Plant hybridizers have been crossing closely related, but nonetheless different, species for centuries. As such, the public is generally not as resistant to this “more natural” activity. For example, you can cross two different species of Echinacea coneflower in order to create a new color variety. Where the public gets worried, is when a gene from a distantly related organisms is inserted into the genome of another. For example, Glofish were made by inserting a gene from a coral into a fish.  There is no realistic way that would happen in nature. Due to the fears described above, there are currently no GMO tomatoes being sold on the market. This is not due to any known hazard to humans, but rather due to the public being wary of a technology that is new, by a process unknown to many, and not having enough time to see what will happen with these “experiments” long-term. There are, however, many other examples of vegetables that are GMO, like soybeans some corn, and canola for example.

So given all this information, what category of vegetable do you pick? Well, the simple answer is that it depends on what you want to do, and how good you are as a gardener. For anyone new to the endeavor and looking to plant tomatoes, I would recommend starting off with the disease resistant hybrids. These are generally the most forgiving. Once you have a good idea of how to grow the plants, maybe you would want to try an heirloom variety or two in addition to your regular stock. Open pollinated plants can be fun as well as you can save your seeds each year and select for certain traits, but you need patience and time. This gives you the power to essentially create something new and unique suited to your specific needs or desires. No matter what you decide, get out there and plant! As I always suggest, get a soil test first for best results!        

Matt Lisy