When should we pick tomatoes?

September is one of the best times to be in Colorado. And one of the most confusing, if you're growing your own vegetables. Since tomatoes are far and away the single most popular veggie that we grow, let's take a look at when we should be picking them, and when should we leave them alone, to continue ripening on the vine.

It all comes down to our often fickle Colorado weather. According to the National Weather Service, the Denver area's average first frost-freeze is October 8th..... but an overnight freeze has been known to come as early as September 8th or as late as November 15th. All this means that as gardeners, we need to be light on our feet, keep our eyes on the forecast, and think strategically. We need to have a plan on how to get as many tomatoes as possible to ripen before Mother Nature shuts down our tomato season.

So for starters, when should we be picking our tomatoes? Some folks are convinced that only a 100% vine-ripened tomato, ready to eat the moment you pick it, qualifies for an A+ rating. I'm not one of those folks.
Birds and rabbits, (who knew rabbits ate tomatoes?), seem especially drawn to a shiney red tomato. So in a effort to out-smart the wildlife, I'm likely to pick a tomato when it is on its way to fully coloring up, but not necessarily there yet. I'll let it finish ripening at room temperature on the kitchen counter. I honestly don't notice any loss of flavor.

By the way, never refrigerate a lovely home-grown tomato unless you want to make it taste like a store-bought tomato. Refrigeration is just one reason grocery store tomatoes taste so flat.

If you don't have wildlife pilfering your tomato patch, ripening on the vine is fine. A fresh-picked tomato warm from the sun is truly one of life's little pleasures. But you should also keep in mind that the clock is ticking on what's left of our growing season.

By picking your tomatoes when they are well into "blushing," but not fully ripened, you're letting the plant concentrate more energy on the remaining tomatoes. With a little luck, you'll get more home-grown goodness in the long run.

Also keep in mind that as our overnight low temperatures begin to drop, 55 degrees and less, the ripening process is going to slow down. Removing tiny tomatoes that don't have a chance of reaching their mature size will help focus the plant's energy on the fruit that has more promise.

In my next blog, I'll offer some tips and tricks on harvesting some of the other veggies that may be growing in your garden. Hopefully, we're at least a few weeks away from making the "big sweep" of our vegetable gardens, picking everything that would be damaged by freezing temperatures. But this is Colorado, after all. I always picture Mother Nature grinning at gardeners here, just to see if we're paying attention.

The Trouble with Tomatoes

I knew my tomato crop wasn't doing too well. Out of my twenty-five plants (ya, I know.... about twenty too many....), some crashed by late July. Others kept on trying, but even more of them had given up the ghost by mid-August. But it wasn't until I taught a class for the Douglas County Master Gardeners that I realized how much everyone else seemed to be having problems, too.

I asked the group of fifty or so Master Gardeners how many of them were having a good tomato year. Not one hand went up. NOT ONE!! Now that's a bad tomato season. Let's take a look at what went wrong.

Problem #1: June. Yup, June. Pretty much the entire month of June worked against those of us with home-grown tomato obsessions. June was too wet and too cool for too long. My tomato plants, which were all in the ground before Memorial Day, pouted the entire month of June. Really. They just sat there. They didn't die, but they didn't grow.

Walls-o-Water would have helped protect the plants from the cool June temperatures, but I was lazy and didn't use them. Pre-warming the soil with Walls-o-Water before I planted would have helped, too. Tomatoes (and peppers and eggplant and potatoes....), don't like "cold feet." Warming the soil for several days with the Walls-o-Water is especially helpful in heavy, clay soil that tend to be slow to absorb the sun's warmth in spring.

Kris, Tagawa's Annuals Co-director, is a big fan of Walls-o-Water, and uses them in her foothills garden every spring. She tells me that as of late summer, she still has the Walls-o-Water on her plants. The plastic teepees have collapsed a bit, but her tomato plants are fine. Mine? Not so much.

The most common tomato concern customers are bringing to Tagawa's diagnostic staff at Dick's Corner is something we see every summer. "Blossom end rot" shows up every year, but it's going gangbusters this summer. It's related to our wet June weather, but didn't have to get out of hand the way it has.

Blossom end rot is characterized by a round, brown or beige leathery circle on the blossom end of the tomato.... the bottom of the fruit, opposite the stem. It's caused by a calcium deficiency just as the fruit is forming. Reaching for the fertilizer really isn't the answer. In fact, too much nitrogen can actually contribute to the problem. The best way to avoid blossom end rot is to keep the plant's roots more evenly moist.

We went from a cool, soggy June to a hot, dry July. Good drainage (well-amended soil and raised beds) would have helped with the soggy part of that equation. By the time July rolled around and the soil actually warmed up, mulching the base of the plants with something like straw would have retained more moisture. All of those techniques could have helped to avoid having the plants go from too wet to too dry. My tomatoes grow in raised beds, and I mulch with straw once the weather is reliably warm. And I try not to let the plants dry out. I didn't have a single case of blossom end rot. My tomatoes did have other issues, which I'll explain in a moment.

Blossom end rot isn't contagious. It won't spread from one plant to another. But much of the fruit that was forming at about the same time during the growing season could be effected. Watch for the first signs of blossom end rot while the tomatoes are small. Remove any fruit that shows the tell-tale symptoms, and let the plant's energy go instead toward making healtheir tomatoes.

Make sure you know how moist the soil around your tomato plants (and all plants, for that matter) really is. Poke your finger down a couple of inches, or use a water meter. Either way, when the top two to three inches of soil has dried out, water thoroughly, but don't over-water. Apply enough water to soak down to the bottom of the plant's rootball. And take it easy with the nitrogen, the first number on the fertilizer package. Nitrogen will promote lots of leafy growth. All that foliage could "steal" some of the calcium that the fruit needs more.

So what went wrong with my own plants, if they managed to escape the blossom end rot that's plaguing so many others? Why did the lower leaves turn yellow so quickly? Why did entire sections of certain plants just call it a day? Quite honestly, I think I set them up for failure. I planted earlier than I normally do, (and felt pretty proud of myself at the time....) I didn't pre-warm the soil. I didn't use Walls-o-Water or any other protection to help buffer the plants from cool temperatures that are always possible in June. And despite my best efforts over the years, including gardening in raised beds, clay soil is still clay soil. In short: I didn't anticipate potential problems from Mother Nature. Silly me.

Okay. Lesson learned. My 2010 tomato crop is already taking shape in my mind. Next year will be different!