Grafted Heirloom Tomato Plants

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Heirloom vegetables have gained huge popularity in the past several years for a variety of reasons. Some gardeners want to raise a bit of history, to produce a fruit or vegetable their forebears would recognize should they suddenly – and spookily –materialize at the dinner table. Others want to help protect global seed stock diversity, insurance against catastrophic loss in our food supply caused by a single dominant breed. Still others love the heirlooms’ variety in color and shape — for example, fluted Costoluto Genovese tomatoes  when sliced across the grain look like juicy red doilies. Pineapple tomatoes are a gorgeous (and delicious!) golden yellow streaked with rose, and Rainbows look like a sunset.

But while all these reasons are important (and at least one is vital), most people are drawn to heirloom vegetables, tomatoes especially, for the flavor. Unlike most of the red tennis balls in the supermarket, which are bred for travelin’ rather than eatin’, heirlooms yield that true tomato taste.

The only problem with heirlooms — something that many growers and home gardeners learned during the cold-water-in-the-face of late tomato blight two years ago — is that they are generally more susceptible to diseases than hybrids. Especially in a whole field of them. It’s the reason our vegetable gardening parents and grandparents gravitated to hybrids in the first place.

Enter grafting.

Grafting, attaching the sturdy disease-resistant rootstock of one plant to the growing, fruiting top of another (the scion) has been a successful horticultural practice for millenniums. Done primarily with fruit trees, which produce for years or even decades,  until recently grafting was rarely performed on annual plants. Too fiddly, too labor-intensive, time-consuming, and therefore too expensive for something so short-lived as vegetables.Yet the renewed interest in heirlooms by chefs and home cooks have combined with the huge upsurge in small-scale home vegetable gardening to create a market demand for a better heirloom plant. As a result, botanists and horticulturists have begun grafting the tops of heirloom tomato plants onto hybrid tomato rootstock.

“They’ve been grafting for commercial growers for a few years now,” says Josh Kirschenbaum, public development director at Territorial Seed Co. in Oregon. “But this is the first year anyone’s selling grafted plants for the home gardener.”

The method used is usually Japanese top-grafting, or tube-grafting. It involves growing an heirloom tomato plant (which becomes the scion or fruiting part), slicing the small plant off its root, slicing the bottom of the heirloom’s stem into a tiny wedge, then splicing it into the decapitated stem of a hybrid root. It’s delicate work. (There’s step-by-step video link below.). You keep the two pieces together at the joint using a specially designed clip, which falls off after the healing process, or a collar, which can be home-fashioned from vinyl tubing. The post-graft care is nothing to sneeze at either. And you’ve got to match the variety of rootstock with that of the scion.

“For one thing, you have to graft a hybrid cherry tomato root stock onto a cherry tomato plant, for example, and a slicing tomato stock onto an heirloom slicing tomato,” Kirschenbaum explains.

While it’s new to American home gardeners, according to Maine Organic Farmer Gardener, “the technique is so popular in other countries that Asian and Japanese companies have developed lines just for rootstock.”

Kirschenbaum says the side by side difference in growth and health between non-grafted and grafted heirloom plants is ‘extremely noticeable.’

“The root stock was huge and that extra vigor may help,” he says.

This year for the first time, some mail order catalogues offered grafted heirlooms to the home gardener – Territorial Seed Company in Oregon sold 8 grafted varieties, several with two different heirloom tomato varieties grafted onto a single rootstock. Burpee offered six, included Mortgage Lifter, Black Krim and Big Rainbow. All are sold out. According to the order department at Cook’s Garden Seeds, they still have grafted plants of Brandywine, Pink Brandywine, Big Rainbow, San Marzano, Mortgage Lifter and Black Krim — $14 (+ shipping and handling) per three plants, oddly, the same price as the non-grafted. Unfortunately, there is no information on the website (www.cooksgarden.com) to let you know that these are grafted, while other heirloom tomato plants offered are not. It’s all that new. (The Spy is SO cutting edge!).

For those of you who, like me, don’t have grafted varieties as some protection against the slings and arrows of outrageous fortune that our beloved heirlooms are subjected to, companion planting and interspersing hybrids with heirlooms helps to stave off major disasters. Usually. Depending. But that’s gardening. Maybe next year a graft or two.

http://www4.ncsu.edu/~clrivard/TubeGraftingTechnique.pdf

http://www.mofga.org/Publications/MaineOrganicFarmerGardener/Summer2008/GraftingTomatoes/tabid/950/Default.aspx

http://www.growingformarket.com/articles/Grafting-Tomatoes

Video on grafting

http://www.youtube.com/watch?v=tHnOYcI6B44

 

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