The new 2013 seed catalogs have been arriving and I noticed, for the first time, that some catalogs are offering grafted tomato plants this year. Well, it turns out they have been available to home gardeners in the US for several years now, while they have been extensively used in Europe and Japan, and in US greenhouse agriculture, for years. The concept of grafting is a very old horticultural practice. Roses and fruit trees (members of the Rose family) are routinely grafted onto rootstock because they do not run true from seed. And of course, we all know the European wine industry was saved when an entomologist in Missouri developed a method of grafting Vitis vinifera scions onto phylloxera-resistant American root stock.
What is new to me is the concept of grafting non-woody annuals like tomatoes, cucumbers, peppers and eggplants. What advantage can be obtained? Grafted tomato plants in the catalogs are priced $8-10 each, so what would make that price worth the benefits? Japan was one of the early adopters of grafted plants, a country where space is at a premium. Then Europe. In the US, greenhouse growers are the economic driver behind grafted plants and the economics are simple. Greenhouses are a large capital investment and have a finite capacity for plants. If the productivity of a given plant could be improved for whatever reasons (vigorousness, soil disease resistance, etc.), say 40-50%, that would be a huge payback for the additional cost of grafted plants. Even for field-grown tomatoes, a significant yield per acre is money in the bank.
Do grafted plants have any benefits for the average home gardener? I think that remains to be seen, but the potential is intriguing. A number of benefits are claimed for grafted plants. Among them are increased vigor, extended harvest and disease resistance. Suppose you take a vigorous, disease tolerant rootstock and graft it with a desirable heirloom tomato such as Brandywine. If the grafted plant can produce even 50% more fruit for the one spot I can devote to a Brandywine plant, it would be worth it to me.
Here are some of the claimed benefits of grafting:
Extended production of fruit. The combination of disease resistance with a vigorous rootstock means that plants will keep growing and producing fruit. For a greenhouse with a controlled environment, that is an obvious advantage. If it proves true in the home garden, that would also be a plus. My tomatoes tend to tire out in late summer. This year they only got about 4 feet up a 6 foot trellis. I am no disease expert but I suspect diseases may play a role in this. Usually I am hoping the couple of fruits still on the vine will mature before cold weather. I think that instead, wondering what to do with the bushels of green tomatoes still on the vine would be a pleasant problem to have.
\If you want to see how grafting is done (and why retail grafted plants are expensive), there is a great video produced by the University of Vermont here. And just a WARNING: While grafting is not GMO, it is a high-tech process used in agribusiness and Monsanto is heavily involved. The Dutch company De Ruiter, a Monsanto company, is the source of seed for the Maxifort, Multifort and Beaufort rootstock which are widely used. Seminis has its own rootstock, Cheong Gang. Johnny’s and others do offer rootstock seed not produced by Monsanto but retail growers don’t always volunteer what rootstock they are using. It looks like Log Cabin Plants sold by Territorial in 2011 used Emperador rootstock from Syngenta in the Netherlands, a non-Monsanto product. For 2013, they are using a rootstock branded “SuperNaturals” and it isn’t clear if this is Emperador re-branded or a new rootstock. If you are concerned about avoiding Monsanto products, you should probably ask what rootstock is used.
I am definitely intrigued by the concept of grafting tomatoes and will probably try a few plants in 2013. Right now I would have to mail order plants, since I haven’t seen grafted plants at any of the garden centers around here in New England (although Home Depot has trialed selling the Mighty ‘Mato grafted plants, but only online). In the US (outside of the greenhouse industry), most home garden activity seems to have started in the Pacific Northwest, with Log Cabin Plants and retailers like Territorial Seeds. Log Cabin in conjunction with Garden Life developed the Might ‘Mato brand and they seem to be the major grower/promoter for now. Retailers like Home Depot, Territorial, Jung, Totally Tomatoes (and allied Vermont Bean Seed), White Flower Farms, and others are reselling selected Mighty ‘Mato plants. The widest selection seems to be offered by Garden Life itself. Plants will also be available from some garden centers (primarily in western US but hopefully in the NE as well). Expect to pay an average of $8 per plant plus shipping (and usually a 3-plant minimum order). And you probably should order early if you are serious because production is limited.
So, do you have any plans to plant grafted tomatoes in 2013? Have you done so before/? I am thinking of trying a grafted Cherokee Purple, because I am such a fan of it and last year was disappointing. Garden Life also offer Paul Robeson, a Russian heirloom that is supposed to be great tasting and early. Then what about Juliet? It is already vigorous and productive, but if I could get 50-100% more fruit from one vine, I only need to plant one of them. I am not ready to try eggplant or pepper yet. I doubt an 8 US$ eggplant is going to be any less susceptible to flea beetle attacks than my 50 cent transplants.