Chapter 13
Pruning Your Plants
It is likely that the final word on how to prune you tomato plants is not yet in. Pruning remains controversial. How you prune your tomato plants is very important, and is one of the major differences between growing
"If you see a megabloom and are able to pollinate it properly, you may be on the way to growing a big tomato. If the variety of tomato you are growing is able to produce a 2 pound tomato on a normal blossom, a blossom made up of two fused blossoms may give you a 3 to 4 pounder, three fused blossoms a 4 to 5 pounder, four fused blossoms a 6 to 7 pounder and five fused blossoms a 7 to 8 pounder. The world record tomato, 7 pounds 12 ounces, is rumored to have been the result of five blossoms fused into one. Now you know why all the big ones are tomatoes for total yield and growing tomatoes for size. Limiting and directing the growth of the plant and the number of tomatoes on the plant are essential to growing a big tomato. Without extensive pruning the likelihood of growing a big tomato lessens considerably. Proper pruning takes time and diligence. (For extreme pruning techniques read the chapter about Dan MacCoy.)
First, you should allow only one or, at most, two stems to grow on your plant. One will be the main stem and the other, a secondary vine. Both vines will ultimately be terminated just above the level of your biggest tomato, the only remaining tomato on your plant. It is likely that your plant will end up being around three and no more than five feet tall, probably, closer to three. The reason for allowing a second vine to grow is twofold. First, the additional foliage will protect the tomatoes from the direct rays of the sun, and secondly, and more importantly, the two vines will provide more blossoms for you to choose from than would one alone. Not everyone agrees with this and some growers recommend only one vine.
As the plant grows, side vines will appear at each leaf junction with the main stem. These are secondary vines and are often referred to as suckers. As noted, one main vine and one secondary vine are allowed to grow. The rest of the secondary vines that develop below the ultimate level of the tomatoes on your plant are terminated after allowing them to produce one leaf. These leaves provide foliage that will cover and protect the tomatoes and stem from sun damage. The only leaves removed from the plant below the tomatoes are those that appear to be discolored, sick, or dying due to age.
Indeterminate varieties of tomatoes develop flower clusters at every third internode (area between leaves) along the stem. Most varieties of large tomatoes typically have four to five flowers per cluster. Allow the two or three largest blossoms in each cluster to grow. Prune off the smaller blossoms in each cluster. At this point, the plant should be about 3 to 4 feet tall. The biggest tomatoes usually form between 24 to 36 inches above the ground, but not always. Keep an eye open for that special MB blossom. Allow the other tomatoes to set so that you will have some eating tomatoes if not a giant. Another option is to allow blossoms to form higher on the plant as you seek out the megabloom. I favor letting the vines grow until you see what you are looking for and if you don't see it, remove the plant. After the flowers have been pollinated and begin to develop tomatoes, you will ultimately allow only one tomato, most likely the tomato resulting from the MB, to grow on each plant.
If you started your seeds on April 1st, and began pollinating on June 15th, you will begin to prune off tomatoes around August 1st. You should be down to a single tomato at one month before your targeted harvesting date. You should remove one tomato every few days until you are left with that one tomato. If you remove all the tomatoes from a plant at the same time, you may cause cracking of the remaining fruit due to rapid growth. It is best to prune off the tomatoes that are the farthest from the stem first, since the biggest tomatoes tend to grow closest to the stem as opposed to farther out on the cluster. It is likely that the tomato which grew from a large blossom will be the survivor of this pruning process.
If this is a plant that has the potential to grow a big tomato, after the tomatoes have set, pinch off all new blossoms on the entire plant. Keep all other new vines and suckers pinched, and allow no more flower clusters. Top your plant and remove all new growth beginning about one month before the tomato harvesting date. This allows all energy to go into developing the fruit during the last month of growth.
Important Dates for Plants Started Between April 1st and April 15th
- April 1st to 15th: Germinate Seeds
- June 1st: Transplant to garden.
- Prior to June 15th: Remove all blossoms unless you see an exceptional one. Deadhead all suckers. As June 15th nears, allow blossoms to begin to form.
- June 15th to 30th: Permit all blossoms to grow, but in each cluster remove the smallest of the blossoms. Keep the large ones closest to the stem. Keep an eye open for a megabloom (MB).
- After July 1st: Pinch off all new blossoms if you have some big ones going. Allow several suckers to grow above tomatoes.
- August 1st: Prune off the smallest tomatoes, one at a time per cluster, until you are down to one tomato on the plant. Do not allow the plant to exceed 4 or, at the most 5 feet in height. Terminate all new growth.
- September 1st to 15th: Harvest tomato.
Late in the season, the lowest leaves on the tomato plant, the oldest leaves, will begin to show their age by curling up, drying out, and dying. Remove them, as they will predispose the plant to the development of fungal infections. This is especially true if the leaves touch the ground.
Grower Comments on Pruning
Due to the lack of consensus among growers about how best to prune plants and tomatoes, the following discussion will include more grower's comments than on any other topic.
"I would remove the suckers, because the main stem stays straighter and thicker. Long ago, I read they should be removed when they reach 2 to 3 inches. Keep in mind that the longer they are on the plant the more they take away from the rest of the plant. Leave the flowers, but when the next cluster opens, then make a choice about which ones you want to keep. If you just want to grow a plant normally, then leave everything. I'm assuming you want big, and big means sacrifice."
"I like to start out growing two stems, then cut off one of them half way up. I get lots of leaves that way, and more food for the plant. I have also grown plants with only one stem and they were still quite full of foliage. You could go either way. I let only a couple suckers form leaves near a nice tomato so it can shade it. Keep pruning to two stems until you see something worthwhile. Then top one off the plant. I look for large blossoms in general. They always give me something good – at least 2 pounds. These blossoms always show up sooner or later on a plant. If not, then let it go for eating tomatoes. I remove all bottom leaves that are touching the soil.
"I also remove any bottom leaves that are diseased or discolored. Leaves are the food factories. Keep as many as you can. Ultimately, I leave about 18" on the bottom without leaves as some of the older leaves die and are pruned off. I prune all the suckers except one, and once I have a nice canopy on top, I remove the growing tip. I try different things all the time, but basically this is what I do.
"When I have a special tomato going, I top off the plant at 6 to 7 feet. With nothing but leaves, all they can do is feed the plant. If there is nothing special going on, I let them go for a late crop. All my winning tomatoes were no higher than my chest. I'm 5', 2-1/2" tall. However, my 5 pound tomato was on the very top. So go figure.
"It is very hard to cut off the last couple of tomatoes. I try to calculate the difference. By cutting them off, how much bigger will the last one get? It's a guess. Yes, the ugly ones seem to be the ones to grow bigger because they were double blossoms to begin with. I have had several 4 pound-plus tomatoes that were perfectly round but scarred on the blossom end. So, the big ones aren't always the double or fused blossoms. It's really up to Mother Nature." Minnie Z.
"I am doing everything this year in a ratio of one to three. If the plant is 6 feet tall, the fruit are set at 2 feet, and two-thirds of the plant is above the fruit. This plant would be transplanted 2 feet deep. I am finding that the best total height for a plant for me is between 4.5 and 5 feet, with about 18 inches being buried." Eddie Z.
"I allow no growth but the main for the first 3 feet of the plant. After that, I allow about five main stems and prune everything else off. You can allow just one if you like, but I like to allow a few more. After you get fruit set (usually in clusters of three), pick off all but one in each cluster. Just to let you know how powerful the Big Zacs are, I allowed one cluster of three to mature and all three went 3 pounds or larger, – over 10 pounds of fruit on one cluster of tomatoes." Paul H.
"When it comes to pruning, I allow the plant to split into two vines at about 18" from the ground. All foliage below this level is removed, and the two vines are terminated at about five feet. All sucker vines are removed as they appear, and the lower flower clusters are removed so that the tomatoes will not be hanging close to the ground. Once there are about six flower clusters on the plant, any new ones are removed. By pruning this way, the tomatoes will be located at the 3 to 4 foot level of the plant." Chris L.
"I allow only one main vine to form for the big ones. I may not have as many blossoms to choose from, but I've experimented with one and two main vines before. I have found that the blossoms on one main stem are larger and the stems are thicker and longer. I also prune all foliage below 12" to 15" from the ground in July to prevent the spread of disease, and I prune off any diseased foliage. I prune all suckers from the plant. I allow the top to grow, but may consider pruning it at 6' to 7'. I keep only one vine all the way up to the top. I prune out anything that starts to form a new vine. I feel pruning the suckers gives me more consistent large tomatoes." Don C.
"My plants have to be big and robust if I decide to do anything with them. If they are, then I don't prune any blossoms on the bottom unless they are puny. I leave the two or three biggest ones in each cluster, and all suckers go. Eventually, I prune to just one big one in each cluster. About this time I stop the growth on top, and have pruned all but the three largest on the plant. A lot of this is just intuition and experience. If one fruit in particular takes off, then I pull all the others. Once I top the plant, I don't allow any more blossoms." Minnie Z.
"I am trying to put a tomato on the scale on the first Saturday of October, so I probably set my fruit later than most. On the 16th of July, I go through all of the plants. I pick off any blooms that are set or dying. I pick off any blooms that are not open and showing yellow. Of the rest, I pick through the clusters and remove all but one flower per cluster. I select the flower that has the best stem leading to the flower and has a flower that is larger than average. I do not select flowers that have a 'kink' before the abscission. If all of the flowers on a cluster are equally or poorly served by the stem(s), I remove the entire cluster. I will leave as many good flowers as I find, no set rule. A few weeks later, a couple of the flowers will not have taken, helping me to reduce my number per plant. Once the fruit grow to golf ball size, I prune off any that are out-of-the-ordinary (i.e. too bumpy, 'bellybuttoned,' too much scar tissue for their age, etc.). By the 15th of August, I do not want more than 5 or 6 tomatoes per plant. By the 1st of September I should be down to two or three – by the 15th of September, no more than two per plant, and sometimes only one." Ron W.
"I allow two stalks on my plants, and allow both stalks to develop fully. I don't let any flowers form on the first 3' of the plant. The others are allowed to form, then I pinch off all but 2 to 3 blooms before they open. Over the course of the month of July, I prune off the growth on the first 1-1/2 feet of the trunk of the plant to help with airflow and prevent disease. I try to get the tomato set somewhere in the 4 to 5 foot area on the plant, and then allow about 2 to 3 more feet above the tomato. My plants are always topped off at about 7 feet." Paul H.
"Most of my big tomatoes have been low on the plant, because I only get the big multifused blossoms early in the season. I try to set fruit on about four big blossoms at different heights. I use an electric bee or a cheap battery powered toothbrush with the brush removed to vibrate the flowers and help with the pollination. When the fruit sets, I remove the rest of the flowers on that truss. After four fruits are set, I remove the rest of the flowers and other fruits that develop during the season." Ron K.
"We remove the lowest tomato blossoms which are the first ones to appear on the plant. The tomatoes are allowed to set when they are at an ideal height of about three feet. If the plants are behind schedule, then fruit will be allowed to set sooner since we are growing them for a specific weigh-off date. All tomatoes that are left on the plant have to be in a good position to grow without any interference from the plant and are in the 2 to 4 foot area of the plant. When they are about 1" in diameter, the fruit with the best position and shape are kept, all others are removed. Eventually, only one tomato will be left on the plant. This final tomato will be chosen when it is about 4 to 6 inches in diameter, if it is showing good growth, has a good shape that will allow it to fill out, and has lots of room to grow. No new tomatoes are allowed to set once the plant has been pruned down to two or three fruit." Chris L.
"All laterals (side shoots) should be removed as soon as they appear, and the main stem of the plant should be secured every 6 inches as it grows. As each truss develops small tomatoes, these should be thinned out, leaving the strongest one to grow on each truss." Bernard L.
Giant tomato growers have some differing opinions about how best to prune, having more disagreement than on any other topic.
Why Prune?
Pruning is essential if you want to grow big tomatoes. One of the secrets of growing big tomatoes is managing the amount of foliage versus the number of tomatoes on a single plant. The goal of pruning is to establish a balance between the amount of foliage (vines and leaves) and the tomatoes on your plant. Pruning, the removal of unwanted suckers and tomatoes will result in one really big tomato. A balance between the amount of foliage and the amount of fruit is a necessity.
Think of a tomato plant as a solar-powered sugar factory. The leaves of the plant use the sun as an energy source to produce sugar by a process known as photosynthesis. Sugar is needed by the plant for additional growth. During the first month or so of a plant's life, all of the sugar produced by the leaves of the plant is directed toward the development of new leaves and the single growing tip. During this first month the plant grows very rapidly, doubling in size every two weeks.
Once the plant's initial leaves fill with sugar, new leaves begin to form on the main vine which continues to grow. Then, other vines, secondary vines, commonly referred to as suckers, start to appear. And, the main vine begins to develop flowers which will later become tomatoes. These suckers, if left alone, will grow just like the main stem and will produce more leaves and flowers and ultimately fruit.
This is when the trouble begins. These new vines, the suckers, divert nutrients from the rest of the plant including any existing tomatoes thereby limiting their growth and size. Suckers also tend to shade the more productive leaves. This is not good for the giant tomato grower. Keep in mind that the tomatoes themselves are unable to produce sugar on their own and so rely totally on the leaves and plant circulation for this vital nutrient.
When trying to grow a giant tomato the goal should be to have a plant that efficiently produces sugar the majority of which is directed into your one big tomato. Thus, the need to prune.
