Any gardeners out there? We grow a modest garden each year, and regular readers of this blog know that each year, our garden plays a central role in our summer blogging activity. This year shall be no different. Our 2008 garden will consist of: tomatoes (2 cherry, 4 regular), beans (3 poles), peas (4-6 plants), zucchini (2 plants), lettuce (3 short rows), and some herbs. The plants have been in the ground for a few weeks now, and everything appears to be off to a good start. I’ll get some general photos in a couple weeks or so.

Now, on to the the main topic for today’s post: tomato pruning. For a few years now, we’ve been using a very simple pruning method that encourages the plants to focus on fruit production rather than supporting a jungle of foliage. The method has yielded fantastic results every time. I’ve written about this in the past, but it was well into the growing season and too late for any readers to take action on their own plants. So, this year, I’m going to show you what we do early enough so you can try the same with your plants. (Note: we grow indeterminate tomato plants; this method doesn’t really apply to determinate plants.)

There are two basic concepts to this approach:

1. Limit the number of stems by removing side shoots (aka “suckers”).
2. Limit the amount and location of foliage by removing leaf branches

In this post, I’m mainly going to discuss how these concepts apply to the first time you prune a tomato plant. And when should that be, you ask? Well, we perform the first pruning once the plant has a well-defined flower cluster.

Now, as you hopefully already know, flower clusters are where the fruit will eventually form. The more sugars available to the fruit, the larger they will be. So, with the first (i.e., lowest) flower cluster on the stem, you have a great opportunity to produce some beautiful, large fruit, like the ones pictured.

The first task is to remove as many leaf branches (and side shoots) below the first flower cluster as seems reasonable, with the eventual goal being to remove them all. (Use common sense. For example, if following the rule would mean you’d leave the plant with just a single, under-developed leaf branch, don’t do it. Remove some of the lowest leaf branches and then come back a week or so later and continue where you left off.) Here’s a before-and-after sequence from one of our plants:

You’ll notice that I left a couple branches below the first flowers; I’ll come back for those after the foliage above the flower cluster has grown a little more. However, the suckers growing from the crotches (or “axils”) between the main stem and leaf branches are coming off right away. A sucker will become a parallel stem to the main stem and will divert roughly half the sugars that rise up through the main stem. We don’t want to deny our first-level fruits those sugars, so off they come!

To the right is another before-and-after pair. Again, I’ve left a couple leaf branches immediately below the flower cluster… for now. Remember, leaves serve two main advantageous functions on a tomato plant: they “gather” sunlight for photosynthesis and they shade the developing fruit. Unfortunately, they are also susceptible to disease, especially when allowed to remain in contact with the ground. This is why we remove the lower leaf branches: they are usually in the shade, they don’t have any fruit to which they can offer shade, and they are more likely to be a starting point for disease.

Next, let’s take a closer look at those side shoot suckers. Whereas the low leaf branch removal happens early in the growing season, you’ll be removing suckers for much longer. But don’t worry — it’s very easy to do once you know what you’re looking for.

As I said above, a sucker will become a parallel stem if allowed to grow. A plant with many stems (especially emanating from low on the plant) will result in the sugars being rapidly depleted as they rise up. A plant with few stems will limit the number of fruit it produces. On our (indeterminate) cherry tomato plants, we usually allow just 3 stems (but let them grow to about 6-7 feet!), and on our regular plants, we usually allow them to have 4 stems. The relationship is simple: fewer stems means fewer, but larger, fruit; more stems means more, but smaller, fruit. So, tailor your plants to your preferences!

We typically try to stagger the sucker stems in between one or two flower/fruit clusters as you move up the main stem. So, for example, we might let one sucker grow above the first fruit cluster, and then allow a second sucker to grow after the next two clusters. We then might let one of the secondary suckers itself split one time above that stem’s first cluster. There are no hard and fast rules. You’re just trying to control the flow of sugar to “tune” the fruit produced by your plant. Naturally, each plant is a little different and you just sort of have to evaluate each one as it grows. I know it sounds involved, but it’s really quite simple once you know what you’re looking for, and the results are totally worth it.

We adopted most of our pruning strategies from this article, which does a really nice job describing why this works. It also has some nice diagrams. My hope is that the real-life examples shown in this post will complement the information in that article, and give you confidence to try the techniques on your own plants!

This entry was posted by Steve on Sunday, May 18th, 2008 at 7:04 pm and is filed under Photo, Yard/Garden. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.