Grafted Tomatoes

San Marzanos as of 24 August

Mighty ‘Mato sent me three grafted tomato plants to trial this summer – a grafted Homestead 24, a grafted Heatwave II and a grafted Costoluto Genovese. Grafted plants of any kind are basically one plant’s upper portion spliced into a root stock from a different type.  The objectives are several, but two that many gardeners struggling with tomato production this year will appreciate are improved disease resistance, (the primary objective of grafting), and increased productivity, (often a secondary benefit).  

“The root stock is about 4-5 times the size of regular tomato root stock,” says John Bagnasco, President of GardenLife in California. “Because of that, it wants to push a lot of vigor into the top part of the plant.”

Grafting has been with us for millenniums – fruit trees and roses are the things we usually think of in connection with grafting – but several years ago, vegetable and seed companies began to graft vegetable plants. I’ve been curious about them, so was really tickled to get three plants from GardenLife to trial.

“We like to do testing all over the country,”  says Bagnasco. “The three we sent you were supposed to be heat tolerant, and the Heatwave and Costuluto were also Humidity tolerant.”
Unfortunately, that wasn’t my experience with these plants.

“This year we sold a million grafts – and we have had mixed results around the country,” says Bagnasco, “but 80% of the people who contact us are ecstatic. The Mid-West especially has had problems, and another problem is that people are still burying the graft [when they plant], and when you do that, it ruins the tomato.”

The instructions are clear about making sure the graft is well above the soil surface, so I was careful (and have planted grafted fruit trees before). I put the Costoluto and the Heatwave – on the south side of the garden in a spot that was all but fallow last year. I had planted beans there early last year, but once they were done, had covered the spot with straw. I was hoping the ground would be a good spot for them, but not so much. Those two plants have suffered terribly from early blight, fungus, splitting, rot and critter attacks even though I’ve feed them with organic food (Bagnasco says water-soluable fertilizer does not do well “Organic is the way to grow them”), tended them, clipped off the early blight. I didn’t prune them, something Bagnasco says produces a healthier plant with better production.  Both plants set a lot of fruit, but offered little that was good enough to eat. I’m about to yank them out when I get a minute or two in the next few days.

Grafted Costoluto Genovese on left, Heatwave II on right
The third grafted plant, the Homestead tomato, I stuck in the middle of a short line of Supersauce, and San Marzano, and it’s doing better, (though many of my tomato plants are suffering from blight or something right now). Lemon peppers were in that bed last year, but I put in tomatoes anyhow. I break the ‘rules’ by planting Solanacea family members in the same spots year after year, because I have so many tomato and pepper plants and only so much space. Sometimes it works, sometimes you can tell it was a bad idea. It seems to have as much to do with weather and sunshine and air as it does with what’s in the soil. I try to interplant almost everything in the garden with other things – herbs pollinator favorites, a bean plant or two maybe, some lettuce, radish, whatever, to keep things lively in hopes of creating a balanced ecology in the garden. Sorta works.
Grafted tom’s right background,  Supersauce on left

This grafted Homestead bracketed with Supersauce and San Marzano had a tough time earlier, but has squared itself away pretty much and is giving us a nice amount of slicing tomatoes. So is it the plants? The soil? Air flow? (which should be the same for all three plants). The variety? I don’t know, though I do think the soil is partly to blame.The tomato plants on the left in the photo at left were started at the same time as all the others, but were planted a full month later, which may explain their current health (though I can see trouble starting down at the bottom).

 The photos on the Mighty ‘Mato site of their grafted plants are impressive, and taken, Bagnasco says, in their trial garden in Oregon, not exactly your best tomato-producing region. And I’m very aware of the wide range of tomato experiences people have been having this year, even people as close in geographic proximity as Sabine Harvey’s garden and mine (same county 12 miles apart). Has anyone else tried grafted vegetable plants? If so, what’s been your experience, please?

Bagnasco says they graft a wide range of fruit and vegetable plants, and says that grafted watermelon is a particularly impressive producer as compared the non-grafted. I hoping to get a chance to try to grow one next year. In the course of the conversation, he mentioned some new varieties of tomatoes being developed from a species that was brought back from Galapagos that sound fascinating (delicious — it’s all about the eating for me). Apparently 60 Minutes thinks they sound fascinating too; they’re going to feature them with other new phytonutrient plants in a segment this fall.  Never dull.

5 Comments on “Grafted Tomatoes

  1. I don't think you should evaluate grafted plants until you get a chance to grow a grafted and ungrafted plant of the same variety side by side. i did that this year (grafted the plants myself). so far brandywine and speckled roman grafted plants are still going strong, with just a little blight, but the ungrafted plants kicked the bucket long ago. i had a lot of fruits ripen earlier when it was warm, but not much recently after the cool weather.


  2. Good advice, Julie, and thanks much for sharing your experience. I've grown Costoluto Genovese for a number of years with great results, but a side by side same-year test is really what's called for. I'd love to hear if anyone else has had any experience with grafted veg plants.


  3. I am just glad to see that some one else has some sorry looking tomato plants at this point as well!!

    As for grafted plant, I don't know… Since I grow so many tomato plants, I think it would probably be cost prohibitive.


  4. Hi! Biochemist turned stay-at-home mom and gardener here. I decided I needed to plant grafted and ungrafted tomatoes next to each other, and compare results. I planted Brandywine, grafted Brandywine, and yellow Brandywine in the same bed (which last year housed Brussels sprouts). It has been cold and rainy this spring and summer in WI, and just now got over 90 degrees this week. I've had ripe tomatoes from these plants for a week or two, and so far the yellow Brandywine is blowing the other two out of the water. The grafted Brandywine gave me the first tomato, but the ungrafted Brandywine plant is larger and has set more fruit.

    The grafted Brandywine got hit with a touch of frost this spring where the other two didn't, and hasn't seemed to bounce back from it.

    I didn't use fertilizer, but every fall I add 2-4 inches of compost to each bed.

    Fruit trees are my speciality, so I was very careful not to bury the graft. The other two plants, I pulled off bottom leaves and buried them as deep as I could, with just 4-6 inches left above ground.

    The grafted plant has not been worth it's $10 price tag.


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