by Gena Moore, CFSA Organic Research Coordinator | Apr. 7, 2016 –

Grafted tomatoes vs. non-grafted

Left: Grafted tomato plants. Right: Non-grafted tomatoes in a field severely infested with bacterial wilt.
Photo by Josh Freeman.


Tongue Approach Grafting Technique

Heirloom tomatoes are unique, eye-catching, delicious, and difficult to grow. Because these plants have not been selectively bred for disease resistance, they can be susceptible to pathogens and have low success rate in the field.

One way to combat these issues – and stimulate plant productiveness – is through grafting.

Grafting is when you join two separate objects together, in this case, a rootstock and a scion. By grafting an heirloom scion (the top part) to a disease-resistant rootstock (the bottom part) you can create an heirloom tomato plant that will be more productive and healthy. This grafted plant will still produce those unique, eye-catching, delicious fruits; and more of them!

Tools and Supplies

There are a few things you need in order to graft tomatoes:

  • Rootstock (the lower portion of the grafted plant): select a hardy, disease-resistant variety.
  • Scion (the upper portion of the grafted plant): heirloom or other desired variety.
  • Grafting clips – plastic, spring loaded clips work great for the tongue approach.
  • A single edge razor – one from the drugstore is fine!
  • A spray bottle filled with clean water.
  • 3-4” pots and extra potting soil.
  • Disinfectant, like a diluted bleach solution.
  • Healing chamber – a small confined area with high humidity and complete darkness. You can buy domes that fit over standard size flats or get creative and make your own healing chamber.

Expert Tip

The tongue approach grafting technique is great for beginners. You will have a higher success rate as compared to some other techniques and it can be applied to many other crops. Once you master the tongue approach, try moving on to top grafting.

Step 1: Set up Work Area

Grafting tomatoes - step 1

Ready your work area by cleaning the work surface, organizing your materials, and designating specific areas for the rootstock and scion.

For example, always keep your rootstock on the left and scion on the right.

Step 2: Prepare Your Plants

Photo by Gena Moore, CFSA

Remove the rootstock from the flat and cut the top off, roughly 4 inches above the soil line, and remove any remaining leaves/cotyledons.

Remove the scion and defoliate, leaving only the growing point and few leaves at the top. This reduces transpiration and allows the plant to revert most of its energy to healing the graft.

Step 3: Make the Graft    

Photo by Gena Moore, CFSA

Cut the stems at a 45° angle:

  • Rootstock: downward
  • Scion: upward

Make the cuts at the same height above the soil line and 80% through the stem. Once the cuts are made, slide the plants together and place a clip around the graft area.

Step 4: The Healing Process 

Photo by Gena Moore, CFSA

Place the two grafted plants in your pot, add extra potting soil as needed. Water the soil well and mist the plant with your spray bottle. If you’re doing multiple grafts, mist the plants frequently.

Finally, place all your grafted plants in the healing chamber for three days, slowly introduce light and wean the scion from its roots.

Post-Graft Care

The grafted plants should stay in the healing chamber, in complete darkness, for three days.

  • Day 4: Place the plants somewhere with indirect light.
  • Day 5: Cut halfway through the scion’s stem slightly below the graft area ad increase light.
  • Day 6: Cut the rest of the scion’s stem and remove the lower stem from the pot. Place as normal in the greenhouse or another transplant area.

After your plants have completely healed and established a good root system, they are ready to be planted in your greenhouse, high tunnel, or field. Do not plant the graft union below the soil line. Be sure to check below the graft area for any stems or roots that should be removed.

Trellis and prune as normal and enjoy a bountiful harvest of heirloom tomatoes.

Useful References

Visit our website for more info on tomato growing.