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Grafted Tomatoes: Fad or Functional

Written by Stephanie on March 17th, 2012

Just as fruit trees are grafted to provide disease resistant rootstock while producing good tasting varieties of fruit, tomatoes are increasingly being grafted for the same reason.  Grafted tomatoes are common in Asian countries and Europe.  They are just starting to reach North America, however.

Tomatoes are susceptible to many diseases.  Most people know to buy tomatoes that are resistant to some of these, such a fusarium wilt.  However, some very good tasting heirloom tomatoes are not resistant to the common diseases most gardens harbor today.  In order to grow them, it is necessary to graft the heirloom scion, or top, onto a hardy rootstock, or bottom, that can withstand these problems.

Grafting tomatoes is not as difficult as grafting peaches or other fruit trees.  All you need is two tomato plants, a razor, and a grafting clip.  The grafting clip holds the graft together long enough for it to heal and can be bought cheaply from many tomato supply houses.

The two tomato plants should be a few days old and the same diameter as each other.  Cut the top off the rootstock with the razor.  Use a cut that is straight across and level.  Discard the top of this tomato plant.  Now, cut the top off of the scion in the same manner.  Carefully thread the cut end of the scion into the grafting clip.  Now thread the grafting clip onto the top of the rootstock until the two tomato plants are in firm contact with one another.

In order to heal, the tomatoes must be kept humid and in low light for about three days.  An easy way to do this is to put the pot in a clear plastic cup and put another clear plastic cup over the top.  You may need to use a stick to support the top of the scion so that it does not break above the graft.  This creates a mini greenhouse that will keep the plant humid enough to heal.

The low light is necessary because you want the tomato plant to concentrate on healing, not producing foliage.  Instead of direct sunlight, ten percent sunlight for three days will allow it to heal the best.  This can be accomplished by putting paper around the outside of the cups so only the top is open to light.

At the end of three days, the graft should be healed.  The plant is still a bit fragile, but can be transplanted into a larger container for further growth.  The grafting clip will gradually be outgrown and will drop off the plant when it is no longer needed.  These clips can then be sterilized in a solution of one part bleach and nine parts water for ten minutes, rinsed, and reused.

When planting the tomato in the ground, it should be planted with the grafting knot level with the ground.  This protects the knot and keeps the plant from producing suckers under the knot.


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