Cultivating Better (Tomato) Taste, Part 2

State fruit - Tomato

Image via Wikipedia

In Part 1 of this series, I discussed my decision to grow my own tomatoes, my selection of a Topsy Turvy “upside down” planter, and the problems with advice on the internet about growing tomatoes. In this post, I address various aspects of choosing a tomato variety, establishing appropriate growing conditions, and getting the tomato plant into the planter.

This is not a step by step tutorial. Each brand of planter comes with its own instructions for planting and cultivation, so I won’t duplicate those instructions here. I’ll emphasize some of the key points they make and add my own comments.

DISCLAIMER: My experience, and the insights I present here, apply only to “upside down” container gardening in a mostly arid Western U.S. location, with very high daytime temperatures and relatively cool nights. Also, I’ve tried only hybrid (not heirloom) tomatoes of fairly normal type and size; no cherry tomatoes or beefsteaks.

Choosing a Tomato Variety

There’s a dizzying range of tomato varieties to choose from. One limiting factor is that only a subset of varieties will be available as seedlings at your local home center, garden center or nursery. You can probably find a wider range of choices by buying tomato seeds, but you’ll have to grow them into seedlings that you can transplant into your planter. I have no experience with that approach, so you’re on your own if you want to try it. Buying a healthy seedling is easier.

Heirloom tomatoes picture

Heirloom tomatoes - photo by Antoaneta via PhotoRee (

Typically, your retailer will carry a sampling of plants with some combination of characteristics such as size (cherry/beefsteak), color (red/yellow), usage (paste/salad/sandwich), time to maturity, climate tolerance, and heirloom vs. hybrid. The difference between heirloom and hybrid cultivars is complex to define precisely, and I won’t delve into the subject here, except to say that heirlooms are historically older, having been passed down from generation to generation of gardeners, and are more varied in color and shape than hybrids. Hybrid tomatoes were developed in the last 50 years or so, and are the result of deliberate cross-breeding to achieve a combination of desired traits. Here’s some additional information:

Disease resistance is another significant issue for the novice. Hybrid tomatoes are frequently bred to resist various diseases, so I focus on hybrid varieties. A tomato plant is usually labeled with a set of initials indicating the specific diseases that it combats. For example,“VFFNTA” means the plant is resistant to verticillium wilt (V), fusarium wilt races 1 and 2 (FF), nematodes (N), tobacco mosaic virus (T), and alternaria stem canker (A). Here’s additional information about diseases (and some other stuff):

Tomato varieties are also categorized by their growth habit, which should be appropriate for your growing conditions and the way you expect to use your tomato harvest:

  • Indeterminate tomatoes can grow up to 6-10 feet tall (or more), and must be supported by stakes or cages, and pruned to keep their sprawl under control. They produce fruit continuously throughout the growing season. Indeterminate tomatoes have large root systems, and are not recommended for container gardening.
  • Determinate tomatoes have a limited maximum size, usually about 3-4 feet tall, have a predetermined number of stems, leaves and flowers, and tend to be compact and bushy. They require little if any growth management. However, a true determinate variety will produce one harvest, all at once (in a couple of weeks), then stop producing. They are fine for containers, and because of the timing, most suitable for canning or sauces. A determinate plant grows to a limited size, and dies after its complement of tomatoes ripens.
  • Semi-determinate (or vigorous determinate) tomatoes are a good compromise if you’re using a container, and you want a steadier stream of fruit without having to replant during the season. They grow up to 5 feet tall; they require some support (unless you’re growing them upside down, in which case they just hang down from the planter); and they produce multiple batches of fruit throughout the season.
Tomato seedling picture

Tomato seedling - photo by Random Factor via PhotoRee (

Unfortunately, semi-determinate types are often labeled as determinate, so it’s hard to identify them without asking your retailer. Many reference sources and retailers don’t even mention the semi-determinate category. I was originally unaware of this type, and bought a plant labeled “determinate” at the Home Depot (Bonnie Select, which I chose for its excellent disease resistance). After the first harvest, I was surprised to find that it was continuing to produce blossoms and fruit! It turns out that Bonnie Select (a proprietary cultivar) is semi-determinate, as are the better known Celebrity, Mountain Pride and Sugary varieties. Those are the only ones that I’m certain about as of this writing.

Establishing the Growing Conditions

With the Topsy Turvy planter, the soil and root system of the tomato plant need to be warmed during the day. If you hang the planter under a roof, make sure that the soil container gets plenty of direct sunlight. Exception: in hot climates such as mine (California’s central valley), daytime temperatures of 95°F (35°C) or more can do the job, even when the container is in shade much of the time.

Although the plant requires lots of sunlight and the roots grow best in warm soil, there are limits. Conventional wisdom has it that tomatoes thrive with as much direct sunlight as you can possibly provide (6-8 hours or more daily). However, it’s not really the fruit that needs sunlight, it’s the leaves. The fruit is better off being protected from the sun by the plant’s leaves. Otherwise, the fruit can develop green shoulders or sunscald.

Sunscald on tomatoes picture

Sunscald on tomatoes - photo by Strata Chalup via Photoree (

The daytime temperature in the shade should be between 75°F (24°C) and 90°F (32°C). Higher temperatures are acceptable, as long as you keep the plant watered. If high temperatures regularly exceed this range for a few days or more, try to shade the plant during the hottest part of the day to prevent sunscald or green shoulders. I now have mine hanging under my patio roof so it gets maximum morning sun, but it’s protected from some of the direct sunlight in the afternoon. It endured triple digit conditions a dozen times with no ill effects.

For your tomato plant to flower and fruit successfully, nighttime temperatures need to be between 55°F (13°C) and 70°F (21°C). Occasional short periods (less than a week) outside this range is fine, as long as it doesn’t get cold enough for frost.

NOTE: As I write this, the sun is lower in the sky, and direct sunlight is available in a smaller area for fewer hours of the day. The daytime temperatures are reaching only the mid-sixties (Fahrenheit) and nighttime temperatures are dipping into the forties. And yet my tomato plant has a dozen green fruits still growing, with half as many new fruits just developing. It looks good, but time will tell if I can bring this last harvest to completion.

UPDATE: A few of the largest fruits grew a bit larger, but none of them started to ripen. I harvested about a dozen, and after a week or two in a bowl on the counter, several have actually mostly ripened! The green ones I baked with breadcrumbs. Not bad.

As the upside down tomato plant starts to grow, it initially grows downward, away from the roots. But soon its stems start to search for sunlight by turning upward, which can produce some interesting twists and turns. At this point the plant is still lightweight enough that with strong stems, it should have no problem supporting this upward growth trend. Some branches may extend up quite a ways alongside the container. Then when it starts to bear fruit, as the tomatoes increase in size, their weight pulls the stems down again, producing yet more interesting twists and turns. In my experience none of this growth pattern should present any problems; just don’t try to correct any of the twists and turns or you might break a stem.

Planting the Tomato

Set up a very sturdy support from which to hang your planter. When freshly watered, a mature determinate plant can weigh upwards of 50 pounds. A decent breeze can blow over a stand that doesn’t have a wide enough stance. Ideally, you could screw a heavy duty hardware hook horizontally into the side of an overhead beam, like a patio or pergola ceiling joist. You get the idea.

When choosing soil for your planter, don’t make the mistake I made. I grabbed a bag of soil next to the tomato seedlings at the store, and discovered later that it was garden soil, not potting soil. Garden soil is too heavy and doesn’t drain well, which will waterlog and suffocate the roots. Get potting soil.

Blossom end rot picture

Blossom end rot - photo by Eloise Mason via PhotoRee (

One common problem is blossom end rot (BER). This is when a tomato can’t get enough calcium as it develops, resulting in a sunken, leathery black spot on the bottom which grows steadily larger. It’s not a disease and it’s not contagious, but it sure ain’t good eating. To help the tomatoes get enough calcium to minimiz BER, my local nursery recommends mixing some gypsum (calcium sulfate) into the soil. I haven’t tried it myself yet, but I saw enough BER this year that I’ll try it next year. My best estimate is to use 2-4 tablespoons of gypsum in the Topsy Turvy’s 18 quarts of potting soil. In addition, too much nitrogen in the soil can exacerbate a plant’s difficulty in accessing calcium, so I’ll use a fertilizer with a lower-nitrogen formula.

When planting your tomato seedling, submerge the main stem deeply in the soil. You can cover up to 2/3 of the main stem, including leaves! Just leave the top portion (with its leaves) clear. All of the stem under the soil will sprout strong roots from the little hairs that cover it.

After you add soil to the planter to three inches above the roots, sprinkle in three tablespoons of time-release tomato fertilizer, then finish adding soil. One application is supposed to last 3 months, but with a container, a lot of watering can dissolve the fertilizer more quickly. So mix more of the time-release fertilizer into the soil after 6 weeks, and again every four weeks after that. Don’t over-fertilize, however. Too much fertilizer can lead to other problems (blossom end rot can be exacerbated when the fertilizer provides too much nitrogen).

If nighttime temperatures go below 50°F (10°C), flowering and fruiting can be delayed, so planting too early may not bring the harvest any sooner. It also might encourage blossom end rot if the soil is not very warm. But definitely avoid planting if there’s any danger of frost. (If you can find a way to cover the plant and keep it from freezing, go for it.

In Part 3 of this series I’ll discuss watering, cultivation, problem solving and harvesting.


Posted on 9 November, 2010, in Food and Drink and tagged , , , , , , , , , , , . Bookmark the permalink. Leave a comment.

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