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Growing Tomatoes – Should You Remove Bottom Leaves?

A local gardening group was touring a greenhouse operation that grew tomatoes. The tour guide told the visitors that they removed the lower leaves from the plants because “they robbed nutrients from the upper part of the plant that was producing fruit”. In short, removing lower leaves resulted in a better harvest. It is unclear if that means larger tomatoes or more tomatoes.

Some home gardeners remove lower leaves believing that they will get a better harvest. Others don’t bother and claim they get a good harvest without the extra effort. Who is right?

Growing Tomatoes Should You Remove Bottom Leaves

Growing Tomatoes – Should You Remove Bottom Leaves?

Growing Tomatoes – Should You Remove Bottom Leaves?

After doing some significant research I can honestly conclude that the issue is as clear as mud – but an answer is emerging – read on.  

Robbing Nutrients

The original claim is that the lower leaves rob nutrients from the plant. The first question to ask is, “what does the term nutrients refer to?”. Are they the basic nutrients used by the plant such as NPK? These are the nutrients that a plant uses to produce sugars through the process of photosynthesis. Or does the word nutrients refer to the sugars produced during photosynthesis?

If the lower leaves are using NPK, then it means the leaves are photosynthesizing and therefore producing sugars. Rather than being a drain on the plant this would seem to be helping the plant.

As leaves die they return most unused NPK back to the plant. Lower leaves will therefore not be robbing the plant of these kinds of nutrients.

It is more likely that the tour guide used the wrong term; instead of ‘nutrients’ they meant to say ‘sugars’. If the lower leaves are no longer carrying out photosynthesis effectively they can become a sugar drain on the plant. In this case the upper leaves would have to make enough sugars for both fruit production and for maintaining the lower leaves.

Greenhouse Production of Tomatoes

Let’s first have a look at the growth of tomatoes in greenhouses. Greenhouses grow mostly indeterminate varieties which keep growing taller and taller. As they grow they continue to produce new fruit clusters.  

In greenhouse production (at least in Ontario, Canada) it is common to allow each plant to hold 15-18 leaves which supports 5-6 fruit clusters. This gives a 3:1 ratio of leaves to fruit cluster.  A single plant can be grown for 9 months and can reach 50 ft in length. Imagine the ‘module’ of 15-18 leaves slowly moving up from the root system as the plant grows.

Lower leaves are removed to maintain the 15-18 leaf module for two reasons.

The first reason has to do with disease. As plants grow taller, the lower levels of the greenhouse become more humid, increasing the possibility of disease. By removing the bottom leaves the greenhouse operation keeps the floor area cleaner and reduces the risk of disease.

The second reason has to do with available light. As the plant grows, the upper leaves start to shade the lower leaves. With less available light, the lower leaves can reach a point where they draw more sugars from the plant, than they can produce themselves, having a negative impact on fruit production. Greenhouses maximize their growing space and plant as close together as they can. To prevent any impact on production due to a loss of light, they remove lower leaves.

The above information was obtained from Dr. Barry Micallef, University of Guelph, who specializes in plant nutrition and greenhouse operations. Other references indicate different ratios of leaves to fruit clusters. For example, the Alberta government recommends a 1:1 leaf to tomato cluster ratio and a study in Brazil found that a ratio of 3:2 produced the best yields.The ratio does depend on the variety being grown and may also depend on other cultural conditions.

The University of Arizona report on growing tomatoes says the following. Keep in mind that Arizona is hotter, and sunnier than most of North America.

“Some growers prefer to shade tomatoes, while others do not. Theoretically, shading will reduce photosynthesis, and therefore total yield, however, this has not always been shown in controlled studies. In fact, in some studies, total yield was improved using 30% shadecloth. Shading can improve fruit quality, since direct sunlight on fruit can cause yellow or green shoulders, cracking, and russeting. Alternatively, older leaves can be left in place to shade the individual fruit trusses. In areas of high summer temperatures and humidity, shading may be necessary to keep temperatures within a reasonable range.”

Removal of lower leaves does seem to be the common practice in greenhouse production.

Growing Tomatoes in the Home Garden

Home gardeners grow both determinate and indeterminate varieties of tomatoes, and these may need to be treated differently.

Determinate tomatoes are genetically programed to only grow to a certain size and they rarely get large enough to have a module of 18 leaves and 5-6 fruit clusters before they stop growing. The lower leaves of these types of tomatoes never need to be removed to maximize yield.

The size of indeterminate plants will depend on where they are grown. A long growing season will produce taller plants. In northern climates we struggle just to get the plants producing fruit before the first frost. The plants never get very tall here and therefore it is not necessary to remove lower leaves to maximize yield. In warm climates where you can grow tomatoes outside for much of the year, it might be beneficial to remove lower leaves once you have 18 leaves but this depends on how close together you plant. If your plants are grown with adequate space between them, light will reach the lower leaves and they don’t have to be removed.

When lower leaves start getting yellow it is a sign that they are shutting down and they should be removed before they become a sugar drain on the rest of the plant. As long as they are green they are photosynthesizing and producing sugars for fruit production.

Tomato Disease Control?

In the last few paragraphs I talked only about fruit production. What about disease control? The common advice for gardeners is that they should remove lower leaves so that soil borne diseases are not splashed up onto plant leaves. This certainly seems to make sense – but is it true?

A number of diseases are not spread by splashing water. Fusarium wilt and verticillium wilt are both fungal infections that take place at the root level, not on the plant itself. Late blight can only live on living tissue and so does not overwinter under ground. However a few diseases can be spread from soil to a plant with splashing water, early blight and anthracnose being examples.

Cleaning up remaining plant material in the fall is the best way to prevent diseases next year. Adding a good mulch is also effective since it prevents diseases from being transmitted from soil to the leaves. In fall you should also remove the mulch along with old plant material – you can’t really separate the two.

Another way to prevent diseases from the soil is to remove the lower couple of leaves. Splashing water from the soil will not rise up too far, so removing a couple of leaves can be effective to prevent some diseases. If these leaves are removed too soon, it will delay the production of the first fruit cluster because the plant needs a certain amount of excess sugar built up before it starts to fruit.

The best approach is to mulch under the tomato plant. Leave the lower leaves on the plant. If you tend to have disease problems you can remove a leaf or two after the first fruit is set. If you don’t have disease problems, leave the leaves on for a while longer.

My experience is that the wilts  and early blight infect the plants, but don’t interfere significantly with the harvest. Keep in mind I am in a northern climate, zone 5, and I don’t grow heirlooms – yet. Late blight just kills the plants so quickly that removing leaves once you see the disease will make no difference. I rarely remove the lower leaves.

Growing Tomatoes – Should You Remove Bottom Leaves?

For the purpose of fruit production there seems to be no benefit in removing the lower leaves in the home garden so long as the lower leaves are still green and getting enough light. Once they yellow remove them. If disease is a problem for you, there is a benefit to removing the lower leaves to combat diseases that are splashed up from the soil.

References:

The following are excellent references for growing tomatoes:

1) Diseases and disorders of Tomatoes: http://edis.ifas.ufl.edu/hs200

2) Growing Tomatoes and Pruning Tomatoes: http://umaine.edu/cumberland/files/2012/10/Pruning-Tomatoes.pdf

3) Photo Source: Dan Klimke

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Robert Pavlis
Editor of GardenMyths.com
I live in southern Ontario, Canada, zone 5 and have been gardening a long time. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

I hope you find Garden Myths an educational site that helps you understand your garden better.

29 Responses to 'Growing Tomatoes – Should You Remove Bottom Leaves?'

  1. Jason says:

    Ive always removed the lower branches off all my plants up to the first bunch of tomatoes. And ALL suckers. Always yield good harvest. Northeast Ohio. I have no opinion about leaving all branches on, since ive never done that. I do this to allow more sunlight into the plants. Im somewhat limited in space.

  2. John Devos says:

    I have 2 tomatoe plants in pots how is the best way to grow them ?

  3. Tom Mooney says:

    Thank you for the article and the responses to comments. I’ve learned a lot from both.
    I have a long growing season which promotes tall and very dense plants. My unscientific observation is many of the blooms are in the interior of the plant and less easily accessible to pollinators. Does it follow that removing leaves would help pollinate blooms in the interior of these plants?

  4. Sue chapman says:

    This is my first of growing tomatoes, I turned a flower garden into a vegetable garden, mostly concentrating on tomatoes. I am growing indeterminate tomatoes. They are already over 3 feet tall. I want bigger fruit production. Any advice?

  5. Erin says:

    I always keep the sucker leaves that come in around the top but the lower ones I snip off .. They most likely will never produce any fruit and will just make more shade! Less air flow more disease and pest problems! And yes I do snip off the bottom leaves.. But not too many.. More leaves= more sugars = sweeter fruit😋… I also bury them deep or sideways covering more stem and a few extra branches for more root production , larger stems leaves the plant much stronger !!

  6. Ben Anderson says:

    A friend of mine works in greenhouse production of tomatoes and they remove a leaf from behind the tomato truss, the idea that this will strengthen the truss and produce better fruit. Is any of that true?

  7. Marisol says:

    I saw pictures of tomatoes growing in plots in Israel and the plants had little or no leaves but had lots of fruit. How is this possible?

  8. mohsin bajwa says:

    what happend if cut off all the leaves of tomatoes plants ?

    • In some plants, the plant will die. All plants have stored food in their stems and roots – that is why you can take hardwood cuttings with no leaves and grow a new plant. Tomatoes have lots of dormant buds as well as large root systems and I would expect that the plant will just keep growing.

  9. Tatianna says:

    This was very helpful. Thank you.

  10. Gary Sweeney says:

    Why cant you and ppl like you just give a straight answer on anything ?
    Gary

  11. Denie says:

    I have about 20plants I have removed a. Significant amount of leaves on half .I will let you no what happens. I’m in South East Oklahoma.

  12. Deborah Pratt says:

    thank you for a very informative well balanced article – but one more question – do tomatoes ripen with LIGHT or with HEAT? (or both??) Specifically, do they ripen better, on or off the plant, in direct sunlight – or would they do better in a warm, shady spot eg a clean drawer where they can be regularly inspected? Mine are in a tray on the kitchen table at present, since a wind storm knocked them all flat and some broke while we were picking them up. Memo: use stronger stakes next year. regards, Deb (Woodbridge, Suffolk, UK)

    • They ripen faster with warmth, and slower if kept cool. Wrap each one individually in newspaper and put them in a box or paper bag. A liquor box with dividers works well. This keeps the light out, and keep in the ethylene gas produced. You can also add an apple or two to increase the ethylene gas which helps ripen fruit. That is the common advice – hope none of it is a myth??

  13. Bonnie says:

    Last year, I did a very small scale experiment with six tomatoes (I told you it was very small). On three, I removed the bottom two or three leaves once the plants were about three feet high. On the other three, I did not. Otherwise, watering, fertilizing, light was the same. i did get some fungal spots on one of the three tomatoes that I had not cut off the bottom leaves. This certainly doesn’t prove anything, but since it takes all of five seconds to remove any leaves touching the soil, I’ll probably continue to do it.

    I do wonder about pruning suckers on tomatoes. I don’t care if my tomatoes are bigger or not, I still get more than I can use. Is it really worth the bother,unless you’re looking for size?

    • I have not researched the removal of suckers well enough yet, but I do know people who do it, and others who don’t and both get lots of fruit. I need to blog about this some day. I suspect it has more to do with how you stake the tomatoes, and how closely you plant. Plant farther apart, and there is room and light to leave the suckers. Plant close together and it becomes a problem.

  14. Ken says:

    Hi Robert,

    By saying 18 leaves, do you really mean leaving only 18 single leaves or 18 branches?

  15. Shawn says:

    Hi Robert,
    Thanks for the great perspective. I agree with you. I do remove lower leaves for better water coverage using my stake drip sprayers and also when the leaves are not robust and healthy and showing stress..

    Shawn in Northern California.

  16. Carol Clark says:

    Hi Robert,
    On CBC’s Radio Noon, Ed Lawrence commented on harvesting tomatoes last week. As you said, removing the leaves exposes the fruit to light and hastens ripening. He suggested placing the leaves which have been removed on the ground at the base of the plant where they will release ethylene which should hasten ripening even faster.

    • Robert Pavlis says:

      I don’t think that is a very good idea:

      a) the amount of ethylene produced would be very small, and wind would quickly remove it from the area. I doubt it would have any real effect on the upper fruit.
      b) the lower leaves are the ones that are normally attacked first by diseases. Now you lay the diseased leaves below the plant. That does not seem to make sense to me.

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