Grafted tomatoes show advantages, particularly for high tunnel production. A Purdue extension publication, Techniques for Tomato Grafting, and the video provide a step-by-step guideline for small growers to explore this technique.
I am often asked. When should I start to plant the seeds to produce grafted plants? The chart below shows a general timeline and materials needed to produce small amounts of grafted tomatoes. Generally, the younger the plants are grafted, the faster it recovers. Plant growth delay during graft healing should be less than seven days if plants recover smoothly. The delay does typically not make a noticeable difference in the size of seedlings compared to standard tomato transplants after the grafted plants are grown in a greenhouse for more than two weeks before transplant. Grafted plants could grow faster than normal transplants after fully recovering, assuming cell size does not limit their growth. That said, there is no need to start seeds much earlier than you would normally.
Figure 1. A general timeline and materials needed for producing grafted tomatoes on small scale.
Graft tomatoes with some of the most vigorous rootstocks may cause plants to grow too bushy because of their vigor. The more significant vegetative growth (grow leaves and shoots) could delay flowering and fruit set. Sometimes, grafted plants might delay harvest for about a week compared to typical tomato plants, although yields of the grafted tomato plants quickly catch up.
Several other factors, such as rootstock selection, tomato variety, fertility management, pruning, and trellis technique, can affect the balance between vegetative and reproductive growth.
It is important to note that grafting will not control foliar diseases. Because grafted plants tend to grow more vigorously than normal plants, they are more likely to create a microclimate suitable for the development of foliar diseases such as leaf mold. When fungicides are not used, it is more critical to use cultural practices to suppress disease development. Giving plants plenty of space, timely pruning and trellising, and maintaining good airflow is vital when growing grafted plants.
If you have questions about tomato grafting and growing grafted plants, please do not hesitate to contact me at guan40@purdue.edu