Fall tomatoes

Here's some of the tomato facts of life.

There's a section in Mark Twain's novel Roughing it where he talks about the beauty of the Mississippi before becoming a river boat captain and how the river changed once he became one.

Before knowing much about the river he could look at it and think "my, how beautiful the water ripples as it flows down stream.' After he was 'experienced' he could look at the same view and instead of seeing it as beautiful might see it as treacherous or difficult as in 'there's a submerged tree that could rip the bottom of my boat out.'

That's sort of like tomatoes and growing vegetables.

Looking at a beautiful tomato loses something when you know the facts of life are lined up against that tomato being local and in season. Or even knowing that a September tomato is probably a different variety growing on a different plant than an August tomato.

So when I see a beautiful tomato in September in Washington DC there are some facts that make me stop and give pause.

Sure you can grow a tomato around here this time of year but usually you have to do a lot of finessing to get it to ripen up and look beautiful.


Here's some of the facts of life.

Tomatoes usually need more warmth for best growth and quality fruit than we usually get around here in September . (look at Knox's vegetable handbook for temperature range).

For Best growth and quality a tomato on average needs an optimum temperature around 70-75 with the minimum temperature of 60 and the maximum at 80. In other words temperatures down in the 50's aren't very good if you are going to get a good tomato crop.

The problem is that our September temperatures generally fall at the low range. In other words, most varieties of tomatoes slow down or even stop growing in our September weather. (one of the reason that so many home gardeners couldn't get their tomatoes to ripen up this year is that we had a cool August with the temperature dropping into the 50's about a dozen times).


Another factor is the amount of daylight. As you’ve probably noticed the days are getting shorter. Much shorter. Tomatoes like nice long days. In September they just aren't getting it anymore. Which doesn't stop them from growing, it just slows them down.

Also, one way of classifying tomatoes is whether they are determinite or indeterminite. Meaning some of them grow to a certain size, put out fruit and then die and others, indeterminate, grow, put out fruit, grow some more and put out some more fruit.

This means that determinate plants that produced back in early August are mostly dead now. To get determinate tomatoes that produce in September you had to plant them to do so. They were planted later than those that produced in August.

And if you are growing a indeterminate plant it might continue to produce this late, but only if its range of ideal temperatures is broad enough.


There are tomatoes that like fall temperatures. We have an indeterminate heirloom tomato that is doing well now. It's the same tomato that did well back in June before the temperatures got really hot. That little Siberian is a nice tomato but it certainly isn't a big beautiful tomato like the ones that came ripe in August.

So, in short to get tomatoes to grow and produce in the fall you have to pick a variety that doesn't mind cool weather and you have to plant this tomato specifically to ripen in the fall.

In other words, those tomatoes you ate in July and August were different tomatoes than the ones you eat in September. September is a different season with a different tomato than those tomatoes you ate back during the hot summer days.

So like that log under the water in the river, that tomato in your share in September is a different creature than the one that was grown to ripen during those long, easy hot summer days of bountiful summer vegetables.