Grafted Tomatoes: The Truth Grows in My Garden

San Marzano tomatoes
I'm growing San Marzano tomatoes in my garden this season.  San Marzano tomatoes are supposed to be the "gold standard" of paste-type tomatoes, with thick walls and very few seeds.

I did some research on them and found out that they have their own website, history, and following.  I discovered there are also imposters out there that claim to be San Marzano tomatoes, but they are mere shadows of what a true San Marzano tomato is like.

But my story is not about the history and cult-like following of San Marzano tomatoes.  My story is about grafted tomatoes.

It all started early in the spring, possibly late last winter.  (Imagine now a fading out of your screen as we return to seed catalog season).

I was browsing through seed catalogs and decided that I would grow San Marzano tomatoes because even though I've never made my own tomato paste or sauce, I thought perhaps I would this year.  I had probably just come inside after a round of snow shoveling so might have thought that some spaghetti made with homemade sauce would hit the spot.  Yes, I would make tomato sauce!

About that same time, up pops an email from the editor of Indiana Gardening asking me if I would write an article about grafted tomatoes.  I replied that I would and then she connected me with some people at Burpee who sent me some grafted tomatoes to grow in my garden.

I finished the article about the same time as I received the grafted tomatoes which arrived late in May in one gallon containers.  Two of the tomatoes were San Marzano. Good, I thought, now I can grow a seed raised and a grafted tomato of the same variety side be side. I'll find out the truth. I'll see if there is enough difference to justify the higher cost of grafted tomatoes.

Earlier today, I went out to the garden after an absence of nearly a week and this is what I found.

The San Marzano tomato plant that I grew from seed looked like this:

Seed grown San Marzano tomato plant

The San Marzano tomato plant that was grafted looked like this:

Grafted San Marzano tomato plant

Which tomato plant would you like to grow in your garden?

Clearly, we'd all like to grow the tomato plant that is not diseased, blighted and ready for the trash.

I don't know if it is a dirty, little secret, but  many of heirloom varieties of tomato plants are not disease resistant and often produce only a few tomatoes before they wither away from some kind of wilt/blight/horrible plant disease.  No one really likes to talk about it because growing heirloom tomato plants is cool. It's popular.  We are convinced the heirloom varieties taste a lot better than newer hybrids. Often they do taste better.  But they don't always grow better.

Unless, it seems, if they are grafted.  The truth of that is growing in my garden

So what is this tomato grafting business all about?  Simply put, a scion from a heirloom tomato plant (the top part of the seedling) is carefully grafted on to the root stock of a nearly wild tomato. The wild root stock has better, stronger roots and is more disease resistant and passes this disease resistance  on to the plant  itself.   It's the same principle as grafting an apple tree or rose but a little trickier because it is done with tomato seedlings.  In other words, leave it up to the professionals to graft tomatoes.

The difference between grafted and not grafted tomato plants in my garden, for this one variety, is striking. After seeing it, one wonders why a gardener would even bother with seed grown tomato plants.

Well, I'll still grow some tomatoes myself from seeds because grafted tomatoes are just being introduced into the retail markets in the United States in the last few years so not every heirloom variety is available as a grafted tomato.   But I am now more than willing to pay extra for grafted tomatoes for those heirloom varieties that I know tend to succumb to disease.

Did I also mention that grafted tomato plants produce more fruit than those grown from seeds? I am going to have to seriously consider actually making some tomato sauce or paste now. I've got all these San Marzano tomatoes...


  1. Holy moly, that is some difference!

  2. Carol...this is a very interesting post and I'm glad to get some first-hand info on this topic from someone I know and trust. Since my garden is shady, I can't grow fruiting crops, and have no way to try the grafted tomatoes. Thanks!

  3. This is very interesting. I have never grown grafted tomatoes. I need to think about this for the future!

  4. Very interesting post. I haven't been interested in grafted tomatoes before, but if they were to use the right heirloom varieties (Brandywine comes to mind, since I've never been able to get more than one tomato off a Brandywine vine) I'd probably give it a try....

  5. GardenLife offered 40 varieties of grafted heirloom plants this year. Other mail order companies like Jung's and Territorial Seed Company also had good selections. People reported harvesting 50-60 Brandywines per plant.

  6. San Marzano is a favorite tomato of mine also I have never tried a grafted tomato plant but I will next year like you and see how it does on some Giant tomatoes that I grow. nice article enjoyed very much...

  7. Yes very interesting. I wonder which varieties for root stock they use? I too would like to try brandywine.

  8. What an interesting post this is! I'll have to give these grafted tomatoes a try next growing season. Thanks for sharing, Carol.

  9. I rememember when I first saw grafted tomatoes in Seattle, but I thought they must be only for difficult climates, but this is very interesting. I'll have to give the idea more thought. I have to say I haven't really had any trouble with heirlooms grown from seed though.

  10. Nice to see yours did well. All mine from Burpee developed early blight and are now pulled. My hybrid organic grown from seed tomatoes from Johnny's seed are growing like a tree with bushels of tomatoes. I guess it is perhaps where you live. I was hoping for a miracle for growing heirlooms with the grafted tomatoes.

  11. Hi Carol,

    I'm glad you had good luck with grafted tomatoes. I tried them for the first time last year and found they're like "super plants!" This year I'm growing one with two different grape tomatoes 'Sun Gold' and 'Sweet Million' grafted to one root and another called 'Pineapple' from Territorial Seed. I'll never go back to other types as they're much harder to grow in my shady garden.


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