Roots that have grown from the scion.

During the last 24 hours, since I last inspected the grafted plants, about half of the first batch grew vigorous sets of adventitious roots from the scion.  When I opened the cover the trays looked like miniature mangrove swamps.  In most cases the grafts had taken and I was able to pinch or cut off the roots.  Some grafts had failed, so I remade those; I’m not very optimistic about those grafts, but it was worth a shot.

It’s a mystery to me why those scions put out roots. I can understand it if it was a bad graft — the scion was doing what it could to survive. But if the graft had taken, and was physically strong, then why develop roots? Not enough sustenance coming from the rootstock?

I grafted one tray from the third batch; two trays to go. I have the beginnings of a complete second group (which I planted when I thought I had to start over) so I have to decide whether to proceed with that or live with the reduced number of grafts that I now have.

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.

I hope it’s a good omen — the first batch of grafts all took, 100%, and are looking good. My plans to graft over the weekend didn’t work out, so I’m going to do an orgy of grafting on Monday and Tuesday.  Every rootstock that can find a mate with a similar-size stem will live. The rest: compost.

Once the survivors of this ethnic cleansing are safely in the healing chamber I will have enough space under lights and over heat to start the second batch. One group of rootstocks and scions is already started, so the rest must follow within a day or so for me to maintain the schedule.

Cutting the rootstock just below the cotyledons

Inserting the scion stem into the grafting clip.

The first few grafted plants: 'Beaufort' rootstocks, 'Pineapple' scions.

While I do not have anywhere near the number I need for distribution, I find that I have several scions and rootstock stems that are close enough in diameter to make grafting worthwhile.  There was only enough time today for me to make a few grafts, but I will do a bunch more tomorrow and Sunday.

After grafting, the roots were watered, and the plants were misted lightly to prevent the scions drying out. Clear plastic domes (also misted inside) were placed over the plants, and they are now in the healing chamber, in total darkness, where they will stay for three or four days while the grafts (I hope!) take.

I am grateful to Richard Blakey at Paramount Seeds for rush-shipping fresh Maxifort rootstock seed to me. This will allow me to get my second batch of rootstocks started, to be followed in a few days by the second batch of heirloom scions.

My hoophouse and seed germination room are filled to overflowing with about 2,000 tomato seedlings, all at slightly different stages of development. Sadly, most of the rootstocks will get trashed — only those for which I can find suitably-sized scions will survive. The heirloom seedlings will get grown out for sale at the farm and elsewhere.

Over the next few days I will move most seedlings into my small hoophouse to make room for the second batch. My larger hoophouse has heat mats, so when the plants make the move they will be subjected, for the first time in their young lives, to large day-to-night temperature swings. This might slow them down a bit, but that’s probably not a bad thing.

Thanks also to Deborah Aiza for the photographs, and the encouragement.

Beaufort rootstocks on April 18. Note the widely different sizes of the plants.

I really wish I had not decided to use Beaufort rootstocks.  From germination to second-true-leaf stage, development of this F1 hybrid is wildly uneven. Since successful grafting relies on a pretty close match of rootstock and scion stem diameters, this has forced me to essentially start over with fresh batches of rootstocks and scions.

Readers may recall that I have to produce three batches of grafted seedlings, which will be distributed to three farms for field planting. Each batch will be accompanied by an identical quantity of ungrafted heirloom seedlings so we can get a fair comparison between the grafted and ungrafted plants–growth, production, and disease resistance.

Today I made a really tough decision. I am abandoning the batches already started — hundreds of rootstocks and heirlooms — and starting over.  I am rush-ordering fresh seed, and going back to the rootstock I used last year, Maxifort. It was more vigorous than I would have liked, but at least it produced equal-sized seedlings.

This puts me a month behind where I wanted to be. I’m not a happy camper right now, but I really had no choice if the project was to proceed.

Batch 1 of the rootstocks

With three batches of rootstock seedlings well established and showing their first true leaves (above), the first batch of heirlooms for scions was seeded today, 10 days after the rootstocks were seeded. Every batch is three 72-plug trays.

The next batch of heirlooms, which will grow uninterruptedly without being grafted — the control plants — will be seeded seven days from now.  It will be interesting to see if the plants for grafting are ready on schedule.

It doesn’t look like much, but I am very happy to see it — a Beaufort F1 rootstock seed, planted just two days ago, germinates and emerges.  Batch 1, three 72-plug trays, was seeded on March 27. Batch 2 went in yesterday, and Batch 3 was planted today.

I have experimented with Beaufort and Maxifort seeds for almost three weeks now, comparing their growth rates and patterns with the three heirlooms I’m using. There is no doubt that the rootstocks grow more slowly, lagging behind the heirlooms for about 12 days then “fattening up” pretty fast.

I am at a point on the calendar now where I have to get things rolling or have my grafted transplants going into the field later than “regular” transplants. That would skew the experiment, so I can’t wait any longer.

I will seed the first three trays of rootstock tomorrow, followed by three trays on days 2 and 3.  I will then wait 10 days (instead of the seven I had planned) before starting to seed batches of heirlooms.

The Beaufort rootstock I am using is driving me crazy. Spotty germination, uneven growth.  When you pay 21.2 cents per seed I think germination in the 70 percent range is spotty.  And when the seedlings do emerge, they are all over the place — some take off as I would expect them to, while others struggle and look as though they are just hanging on.

Grafting tiny tomato seedlings requires that the stem diameter of the rootstock and scion plants match pretty closely.  I mean, we’re looking at a 1.5 mm stem diameter here, so a fraction of a mm throws everything off.

The last batch of Beaufort seed I sowed has yet to germinate. They need light to germinate, so I have them very lightly covered with superfine horticultural vermiculite — just enough cover to maintain a thin film of moisture.  I am waiting, but not patiently.

Two weeks old

There is no doubt that Beaufort, the rootstock tomato on the left, is slower. What worries me most is its uneven growth. Some have only just developed their first true leaves, while others are much further along.  If these were being prepared for grafting, a stem match would be impossible–there are six seedlings with six different stem diameters. The three heirloom varieties are much more consistent in size.

I’m going to plant 20 more Beaufort seeds, using a different growing medium, and see if I get a better result. If not, I will dump Beaufort and go back to Maxifort, which I used last year. It is very vigorous, maybe a bit too vigorous, which was why I decided on Beaufort this year.

It’s disappointing when expensive seed like this produces such spotty results. I got the seed from Paramount, but it was in the original sealed De Ruiter packaging. I’ll be sure to let both of them know about it!

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