Potato Products and Sizes
Potato tubers are available in years when I grow a variety in the field, assuming that the quality of the crop is high enough for sale. Varieties that I find the most useful for breeding and that are also popular are available every year. More varieties are available every other year and I note in the product description whether the variety is grown in even or odd years. Some varieties are rarely grown in the field and are primarily offered as in vitro plantlets instead.
Potato tubers are usually available in two sizes, small and med/large. When only one size is available, the tubers will mostly be small. Small tubers are those that fall through a one inch grid when sorted. Think about the size of marbles on average. Medium/large tubers are the ones that don’t fall through a one inch grid, so they may range from just over an inch to about three inches. I typically try to avoid shipping tubers larger than about three inches because the shipping cost goes up significantly when packages go over a pound. Small tubers will produce one plant each. Medium/large tubers can be cut, yielding a higher number of plants. So, a small tuber packet will give you five plants, while a medium/large packet should give you 10-15 plants.
Potato tubers are field grown, so they have the greatest disease exposure of the three product types. I scrutinize plants for disease symptoms, but you should never expect tubers to be completely disease free. There is always a strong probability of exposure to ubiquitous diseases like early blight, black scurf, scab, and other soil pathogens. I test for viral diseases, but I can’t test every plant in the field, so there is a low but non-zero probability that some viral diseases get through. I grow potato tubers in a similar fashion to what is done in certification programs. I begin with clean cultures from the lab, grow small tubers in pots, and then use those to seed the field crop, thereby constantly interrupting the lifecycle of pathogens. I think that my seed potatoes are similar in quality to certified seed potatoes, given the comparatively high level of attention and testing that they receive, but they are not certified, so there is no independent verification of my belief.
In Vitro Plantlets
|In Vitro Plantlet Instructions|
Plantlets are small plants from tissue culture. They are delivered in plastic tubes or bags, rooted in agar gel. There is an eight week lead time, rounded out to the next Monday for shipping, which how long it takes to establish the cultures and grow them to fill out the tubes. Eight weeks is the normal expectation, but cultures sometimes take longer to establish, and sometimes I have plantlets already in progress that can be shipped sooner. Every variety behaves a little bit differently in culture, so popular varieties are usually more predictable than obscure varieties. I can produce and ship plantlets at any time of year, although they are vulnerable to freezing like any live plant. The freezing risk with priority mail is low as long as you get the package as soon as it is delivered. Plantlets are shipped separately from other items you order (and usually separate from one another as well) and must be shipped in a rigid package, which is part of the expense.
The major advantage of plantlets is that they are established in the lab from a disease free source and are therefore as clean a product as I can produce. They also allow me to continuously offer varieties even when I am not growing them in the field. Disadvantages include the expense and the fact that it takes extra work and care on your part to transplant them to pots and get them established before planting them out. If you have a choice between plantlets and tubers and you plan to grow and save your own seed tubers for many years, I recommend starting from plantlets.
True potato seeds were collected from the parent variety. They may be self-pollinated, cross-pollinated, or a mix of both. Potato seeds never grow true. Each seedling is unique, although each will have many traits in common with the parent. With most varieties, there is a picture in the product gallery that shows an example of tubers grown from the seeds.