What the heck is single-stemming?
Single-Stemming requires you to pinch off the suckers (those extra tomato stems that grow in the notch between the stem and branch of the plant) so that the tomato grows mainly on one stem with only main branches. This allows the plant to focus on setting fruit instead of growing more greenery. When the tomato reaches the top of the trellis you top it off so that the plant focuses the rest of its energy on the remaining fruit below.
We have tried to do this in previous years but it is much more difficult to get to all of the plant when it is caged and after a week or two we usually forget. Then overnight the plant sprawls everywhere and we give up. Not this year. After we saw the youtube video below we were convinced that if we did this religiously it would yield us more tomatoes.
Even though we don't square foot garden (after our very bad experience year 1 of community gardening), this convinced us that in addition to the single-stemming we should also try trellising again. We made really inexpensive trellises year 1 from conduit we bent to shape at Home Depot. But unlike years past, we bought trellis netting this year instead of using single strands of jute, nylon cord, and other trellis materials we have used before (which have all buckled under the weight of the plant before the end of the season).
How did it all work out?
Following this method we were able to fit many more tomatoes in our tomato bed. The trellis netting held the plants up exceptionally well as long as we stayed on top of weaving the new branches through the squares in the net. The single stemming kept the plant looking lean and orderly and still allowed it to set tons of flowers that turned into many, many tomatoes.
Also, we had better air flow that I believe prevented the spread of disease. Our garden neighbor usually crams 20 tomato plants in his 4x8 beds and invariably they are disease ridden by early June. This doesn't bother him because he has so many plants that enough survive to meet his needs, but to us, with our handful of plants, this is very worrisome. This year it was particularly bad, and I feared that it would quickly spread to my heirlooms (which have no specially bred disease resistance) that were only a few feet away.
But lo and behold, it is the end of the summer and whatever was affecting our neighbor's didn't bother ours. We did eventually end up with a little blight but even that took a long time to spread to all our plants, and I believe the air flow made the difference.
The final verdict:
Single-stemming plus deep watering (post coming soon) is the way to go. This is definitely how we plant to grow all our tomatoes in future seasons. The results make it worth the extra work.