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Tomatoes For Tight Places: Determinate or Indeterminate?

Q. Hi Mike: We're trying to decide which tomato varieties to grow in the six small 'square foot' raised beds in our yard this year, and were wondering if there are any reasons to chose between determinate and indeterminate types…?

    ---Mary Ann in Mt. Airy, Philadelphia
A. Yes—and the use of the word 'small' to describe your "Square Foot Garden" style raised beds is probably the biggest…eh, smallest, reason.

'Indeterminate' tomatoes are the classic types; their long vines can easily reach 12 or 14 feet in a season, and act like vines—without the support of a big sturdy cage, they will sprawl on the ground and their fruits will be consumed by slugs and bugs as opposed to you. They need a lot of room between plants, and produce their tasty fruits sequentially throughout the season, bearing new fruit until frost shuts them down.

'Determinate' tomatoes are generally a better choice for small spaces and containers, as they are bred to stay compact and can get by with much less rigorous forms of support. Although they can produce a lot of love apples, their growth slows dramatically after the first big run of fruit appears, and they typically produce the vast majority of their fruit in that one big flush. That's why processors love them; you send the harvesters into the fields, pick all the tomatoes in just a few days and move on.

But most home growers want a sequential harvest instead of all-at-once. You can cheat a little bit by choosing six determinate varieties with different 'days to maturity': That's the average number of days it takes for the first ripe fruits to appear after you put six-week-old plants into the ground. All things being equal, a variety with a 'DTM' of 70 days should come in a week or two after a 60-day variety, and so on. Choose your plants by their DTMs and you might be able to mimic the endless summer of eating that an indeterminate plant would naturally bring.

But you're not going to get huge, beefsteak tomatoes like the legendary Brandywine or Mortgage Lifter from determinate plants; their fruits tend to be smaller—generally paste tamata up to medium-slicer-sized. The variety chart in my 2002 book, "You Bet Your Tomatoes" (just reissued in a brand new edition by Plain White Press this Spring!) lists three determinates that have good-sized fruits: Oregon Spring (first fruits ready about 60 days after transplant);Celebrity (70 days) and the classic Rutgers (75 days; and perhaps the original "Jersey tomato"). Toss in the excellent determinate paste tomatoes Bellstar (72 days) and Roma (75 days) and you're off to the small-space races.

All but Celebrity are also open-pollinated, meaning you can save the seeds from this year's crop and grow them out again next season. Many—perhaps most—determinate varieties are hybrids, whose seeds can't be saved from season to season. (My short list is unusual in having so many 'OPs'.)

Now to make things a bit more complex, Celebrity has been called a 'vigorous determinate.' You'd think that might mean it was a rangy plant that would still only produce one big flush, but luckily it's the opposite. The growers we interviewed for a 1994 'square-foot tomato' article back when I was the editor of ORGANIC GARDENING magazine said that Celebrity stays manageable in size, but produces until frost. It's also considered to be one of the most disease-resistant varieties out there, making it an especially good choice in a crowded garden.

Mr. Square Garden himself, the legendary Mel Bartholomew, was also quoted in that article and revealed that he greatly prefers the massive, tasty fruits of big, rangy, sprawly, out-of-control indeterminate plants. He explained that he remains true to his obsessive engineers precision by heavily pruning the plants and growing them straight up in his trademark tight spacing. But this greatly reduces the yield per plant, and Mel noted that he has the room to grow lots of plants to compensate for this. You might want to try some version of this technique with a big old heirloom beefsteak or two; just be aware that many people (i.e., me) don't recommend pruning except to remove diseased and discolored leaves. The more healthy leaves on a plant, the more complex the flavor of its tomatoes will be.

And that may be the ultimate trade-off here. As Amy Goldman, author of the new and highly-recommended book, "The Heirloom Tomato" (Bloomsbury; 2008) points out, determinate varieties don't generally have the flavor potential of indeterminates, simply because they have a much lower ratio of leaf structure to fruit. Lots of leaves = lots of solar collectors fueling the complex sugars and volatile aromatic compounds that give legendary (and large!) tomatoes like Brandywine, Black Krim, and Big Rainbow the taste that tomato lovers crave.

"I prefer indeterminates in general, because they produce more delicious fruits and do so over a longer season," she explains. "But when space is in short supply, there are options in the tasty world of heirlooms. Manitoba, for instance, is a standout; it's a true determinate, and the 10-ounce fruits have excellent flavor; as good for fresh eating as they are for canning. And although Orange Banana and Flamme are technically indeterminate varieties, they stayed well-behaved in my garden."

I asked Amy if that makes them 'restrained indeterminates'…

"Oh, please: 'Vigorous determinates'? 'Restrained indeterminates'? What's next—obsessive compulsive tomatoes?!"

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