I can’t be sure it is going to work, but it is certainly worth trying. The problem was that the rootstock cultivar I am using, Beaufort F1, produced inconsistent seedlings. Grafting requires rootstock and scion stems to be very close in diameter, and the Beauforts are all over the place. Some are fat, some are skinny. The heirloom varieties (Brandywine, Green Zebra, and Pineapple) are comparatively consistent.

What I have found is that there are enough “matches” to produce batches of grafted tomato seedlings. These batches are smaller — 40 plants per tray — than the plan called for, which was 72 per tray.  But I decided that producing a smaller quantity of grafted plants at the right time — that is, transplants of about the same age as other tomato plants in the farms’ fields — was more useful than the right quantity at the wrong time.

What made this possible is the tiny amount of taper in the seedlings’ stems. The base of a rootstock seedling’s stem might be 2.5 or even 3.0 mm, too fat to graft.  Higher up, however, 2 or 3 cm above the cotyledon leaves, the stem is smaller, in the 2.0 to 1.75 mm range. I was able to find enough scion stem matches of this size to make grafting possible.

As the photo shows, I now have six trays of grafts that all seem to be doing well. I’m a few days away from knowing how many grafts have “taken,” but if I keep the humidity high while the plants are in the healing chamber’s total darkness, it looks like a good bet.

I will graft the remaining three trays tomorrow or Monday. The ungrafted plants of the same three heirloom varieties are doing well in my hoophouse and should end up about the same size as the grafted plants when they are all ready to go to the three farms who are cooperating in this experiment.

Saved by the taper . . . I hope.