Last summer was a tough one in the raised beds that form my vegetable garden. We were in Italy for three weeks during a stretch where temperatures reached nearly 40 degrees. Despite the meticulous watering schedule I left for our children, reinforced by online coaching, the scene was not a good one when we returned.
One plant, however, seemed to weather the storm. It was a grafted tomato called ‘Amish Paste’ that I had planted earlier in the spring. It soldiered on and was still producing medium-sized meaty fruit well into October.
Grafted tomatoes aren’t genetically modified, they’re just using a technique that has been in place for hundreds of years; grafting to rootstock to lend qualities like disease resistance, hardiness and quicker growth to plants. Think fruit trees, grapes, roses, peonies, shade trees; all grafted onto rootstock.
There are millions of grafted watermelon, cucumbers, peppers, eggplants and tomatoes grown worldwide but the practice has been late to arrive in North America. Grafted plants are attractive to commercial growers because the rootstock helps to produce crops that are more productive and resistant to diseases. Why wouldn’t a home gardener want that for their tomatoes?
My plant held up better to the heat than its cousins because grafted tomatoes have much larger root systems than a standard variety. They’re able to find moisture and nutrients deeper in the soil and their vigorous growth helps them to still produce when temperatures soar.
Heirloom tomatoes have found a home on this rootstock. The problem with heirlooms, those varieties that are open-pollinated and non-hybridized, is that while the fruit has many positives often the plant itself was prone to diseases and productivity was less than stellar. Grafting a ‘Brandywine’ onto rootstock lessens the incidence of disease while increasing the numbers of fruit. The gardener gets the best of both worlds.
Two things to remember when growing grafted tomatoes: plant them at the same depth as they are in the container and give them plenty of room. Regular tomatoes can be planted deeper up the stem because they will form roots from that stem. This is a technique often used with seedlings that have become leggy from lack of light indoors. You can’t do this with grafts because it will negate the benefits of the rootstock when new roots form on the stem.
My plant last year was about half again as large as the regular plants I grew. You’ll need to give grafted tomatoes plenty of space with a good support system, regardless of whether they are determinate (bush) or indeterminate (staking) varieties. However, if you’re limited for space you will need to plant less to get the same or more fruit.
Fine Gardening magazine did a comparison of grafted vs. non-grafted tomatoes. They found that for those gardeners who fussed over their tomato patch and did everything correctly the difference in yields was not that significant. However, those who neglected the plants on occasion and weren’t that diligent (small confession-me, sometimes) reaped the benefits because the grafted plants were much more forgiving. That’s my kind of tomato!

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