This bud (removal) is for you: Does early flower removal aid plant establishment in fruiting plants like tomatoes?

In many publications and garden resources you see the suggestion to remove flower buds to improve establishment of new fruit and vegetable plants. This advice is shared for both woody and perennial plants like fruit trees and strawberries and for annuals like tomatoes and peppers. And whenever you see someone stating this as gospel, you see someone else stating that it is false or only anecdotal. So the question is – does research support the advice to remove early plant blossoms to improve vegetative plant growth and establishment? Let’s take a look at some recent, and not so recent, research to see what really happens and understand the process.

The Physiological Process

Prior to my extension career teaching people gardening, I fancied myself a budding (ha ha) plant science researcher. Many of my classes, therefore, were focused on plant physiology and genetics. Not necessarily handy in teaching people the basics of gardening, but pretty damn handy in explaining how plant processes work.

As most upper elementary and middle school students will tell you, plants make their own food in the form of the sugar glucose by using energy from the sun through photosynthesis. That glucose is used in the respiration process to release the energy for the plant to use, transformed into other sugars and compounds for functions around the plant, or turned into starch for long-term storage. Photosynthesis is not an unlimited process and genetics, environment, and other factors play a role in the rate of energy development. So it stands to reason that there are lots of things that have to happen with the finite resources made by the plant.

In plant physiology circles, photosynthesis is called the “source” of plant energy and those uses, such as root, leaf, stem, wood, flower, and fruit production and storage are called “sinks” (sometimes also “pools”). Researchers often discuss these pathways as “source-sink” interactions. Since there are only so many carbohydrates to go around, researchers have long known that when demand is high for growth of certain structures that development of other structures is slowed. If there is a period of rapid root growth, the demand for carbohydrates in the roots increases and the availability for other locations in the plant is decreased. As a result growth in the leaves, stems, or reproductive organs may slow until a supply is restored. But this phenomenon varies by plant species and even cultivar/type, as genetics does play a role in the rate of photosynthesis. Some plants have a higher level of photosynthesis to help offset the sudden upswing of need, and some don’t.

Source: Michael G Ryan, Ram Oren, Richard H Waring, Fruiting and sink competition, Tree Physiology, Volume 38, Issue 9, September 2018, Pages 1261–1266

Think of it like a household budget, but you have a job that only pays you in months that are warm and sunny. You have a set monthly income (the source) and then your housing, utilities, food, and other bills to pay (the sinks). Plus, hopefully you are saving some money for later somehow (another sink). If your bill sinks are greater than your income source, you might dip into your savings a bit, but you don’t want to take it all because you will need most of it in the months when you don’t get paid because it is cold and dreary, or your leaves have fallen off, or your herbaceous bits have died back. As a plant you don’t qualify for credit so the only way to make things work is to cut back in some areas (a sad reality for many on limited incomes). You have to reduce your utility usage, cut back on more expensive foods, find cheaper rent, etc. Similarly, a plant has to reduce the amount of energy used for, say, root growth if it has a rapid leaf growth.

And if you have a kid then the expenses go way up, right? That’s what happens when a plant is just minding its business, enjoying a free and frivolous lifestyle when all of a sudden reproduction comes along. First flower structure development, then fruit development. Plants that have a higher rate of photosynthesis have a higher budget to pull from, so the change may be minimal. But when photosynthesis rates are low, like in newly developing plants with few leaves, unfavorable environments, or genetic limits, the effect can be significant.

So, what about my plant?

The question we always get is, “is it necessary to remove the early blossoms on my ______ plant to help it get established?” For perennials like fruit trees, that would generally be the first few years. For annuals like tomatoes, it would be removing blossoms the first few weeks after planting (and removing any blossoms developed before transplanting).  The answer is…maybe. Or more like, there probably is an effect, but it depends on the plant and environment as to how impactful the effect is. This phenomenon has been observed in several species, including Douglas fir, peaches, olives, and more.

For example, research shows that letting blueberry bushes fruit the first two years after planting (not removing flowers or fruits) reduces the biomass (vegetative growth) AND the yield in year 3. The plants will likely catch up in later years, but if your goal is to get plants established early and have fuller harvests sooner, removing flowers in years 1 and 2 would be advisable.

The same can be said for strawberries. The abstract from this paper from 1953 (I couldn’t track down the full article prior to publication) says that “removal of blossom from newly set strawberry plants helps more in the establishment of a vigorous planting than almost any other cultural operation.” This paper doesn’t measure biomass, but did find that removing flowers on day-neutral strawberries (that produce throughout the growing season) until July 1 resulted in maximized yields in the later season and removal of flowers for the entirety of the first year resulted in maximized yields in year 2 (note: in commercial strawberry production, strawberries are usually grown as an annual or at most a biennial, so maximizing early yields is important).

Now, for the all important tomato (drumroll, please). This study from the 70s found that removal of early blooms on indeterminate tomato plants resulted in larger plants (higher vegetative growth) and that eventually the fruit yield nearly caught up with the controls. They found that when fruit development started, leaf growth was “markedly depressed” and root growth ceased (and there was even some root death). So while there was ultimately a small loss of yield, the result was a better established plant that would likely be able to better weather environmental and disease issues throughout the season.

And beyond establishment, flower and/or fruit thinning on plants with high floral numbers has been shown in many plants (apples, blueberries, peaches, and tomatoes, to name a few) to result in larger, higher quality fruits. The same pathways apply here – each and every fruit is a sink. The more sinks you have, the more “mouths” the plant has to feed. So flower removal is a viable production strategy for many different crops and something that home gardeners should think about if you want the biggest, and juiciest fruits on the block.


  • Chanana, Y. R., et al. “Effect of flowers and fruit thinning on maturity, yield and quality in peach (Prunus persica Batsch).” Indian Journal of Horticulture 55.4 (1998): 323-326.
  • Dejong, Theodore M., and Yaffa L. Grossman. “Quantifying sink and source limitations on dry matter partitioning to fruit growth in peach trees.” Physiologia Plantarum 95.3 (1995): 437-443.
  • Eis, S., E. H. Garman, and L. F. Ebell. “Relation between cone production and diameter increment of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco), grand fir (Abies grandis (Dougl.) Lindl.), and western white pine (Pinus monticola Dougl.).” Canadian Journal of Botany 43.12 (1965): 1553-1559.
  • Hesami, Abdolali, Saadat Sarikhani Khorami, and Seyedeh Samaneh Hosseini. “Effect of shoot pruning and flower thinning on quality and quantity of semi-determinate tomato (Lycopersicon esculentum Mill.).” Notulae Scientia Biologicae 4.1 (2012): 108-111.
  • Hurd, R. G., A. P. Gay, and A. C. Mountifield. “The effect of partial flower removal on the relation betwen root, shootand fruti growth in the indeterminate tomato.” Annals of Applied Biology 93.1 (1979): 77-89.
  • Kim, Jin-Gook, et al. “Effects of cluster and flower thinning on yield and fruit quality in highbush’Jersey’blueberry.” Journal of Bio-Environment Control 19.4 (2010): 392-396.
  • Link, H. “Significance of flower and fruit thinning on fruit quality.” Plant growth regulation 31 (2000): 17-26.
  • Michael G Ryan, Ram Oren, Richard H Waring, Fruiting and sink competition, Tree Physiology, Volume 38, Issue 9, September 2018, Pages 1261–1266,
  • Rosati, Adolfo, et al. “Fruit production and branching density affect shoot and whole-tree wood to leaf biomass ratio in olive.” Tree Physiology 38.9 (2018): 1278-1285.
  • Scott, D. H., and P. C. Marth. “Effect of blossom removal on growth of newly set strawberry plants.” (1953): 255-6.
  • Solomakhin, Alexey A., and Michael M. Blanke. “Mechanical flower thinning improves the fruit quality of apples.” Journal of the Science of Food and Agriculture 90.5 (2010): 735-741.
  • Williamson, Jeffrey G., and D. Scott NeSmith. “Evaluation of flower bud removal treatments on growth of young blueberry plants.” Hortscience 42.3 (2007): 571-573.

Ripe for the picking: Which fruits keep ripening after harvest?

“Will my peppers continue to ripen? How about my eggplants?”  It is common knowledge to most gardeners (and home cooks) that tomatoes will ripen on the kitchen counter, as will bananas and several other fruits.  You know that one day your bananas look perfectly ripe and the next they’re a brown mush But does this work for all fruits?   We often get questions about whether specific fruits will continue to ripen after picking.  And the answer is….. it depends.

How green were my peppers…

One of these fruits is not like the other

The answer as to whether a fruit will continue to ripen after harvest depends on which one of two groups it falls into.  These groups are climacteric and non-climacteric fruits.  In short, climacteric fruits are the ones that will continue ripening after harvest and non-climacteric fruits are ones that don’t ripen after harvest.

Image result for ethylene

This refers to the “climacteric phase” of fruit ripening where there is an increase in the gaseous plant hormone ethylene and an increase in respiration, which drives the ripening process. It is the climacteric fruits that will keep ripening once they’ve been harvested, thanks to ethylene.  The only stage of maturity for non-climacteric fruits after harvest is…..compost.

As long as you’re green, you’re growing.  As soon as you’re ripe, you start to rot. -Ray Kroc

Almost all fruits produce ethylene, but non-climacteric fruits produce them at much lower levels and do not rely upon it as the main driver of ripening.  I’ll go into a bit more detail in a bit, but first – which fruits are climacteric and which are non-climacteric?

Common Climacteric Fruits Common Non-Climacteric Fruits
Apple Brambles (raspberry, blackberry, etc).
Apricot Citrus (oranges, lemons, limes, etc.)
Avocado Eggplant
Banana Grape
Blueberry Melon (including Watermelon)
Cantaloupe / Muskmelon Pepper *
Cherry Pumpkin
Fig Squash (summer and winter)
Kiwi Strawberry
Mango Cherry
*Some evidence of climacteric ripening in hot peppers

Image result for avocado ripe meme

The ripening process

Ripening is genetically programmed – meaning that it is highly dependent on processes that are regulated by genes and it specific to each species.  Parts of the process are started and stopped due to the transcription and translation of genes, which are in turn controlled by signals such as chemical compounds, physiological stages of the plant, climate, and so on.  These ripening processes have a lot of end results – sugars accumulate in the fruit, pigments develop, some compounds that have pleasant flavors develop while others that are unpleasant are broken down, some of the pectins in the fruit break down to make it softer, and on and on.

Tomatoes – the classic climacteric fruit

Getting close…

Research shows that ethylene, the simple little gaseous hormone plays a crucial role in the ripening of climacteric fruits by altering the transcription and translation of genes responsible for ripening.  Ethylene is the dominant trigger for ripening in these plants.  Ethylene receptors in the cells are triggered by the presence of the gas which leads to cascade effect.  This is why ethylene can be introduced from other fruits to trigger ripening in fruits that aren’t ready to ripen.  If you’ve heard of the tip to put an apple in a bag full of some other fruit to get it to ripen, it actually works – as long as it is a climacteric fruit.

The same ripening processes happen in non-climacteric fruit as well, but they are not dependent on the presence of ethylene.  In fact, these pathways are also present in climacteric fruits – the ethylene-dependent processes are just the dominant (and faster) way that they ripen.

Controlling ripening

The dependence on ethylene for a vast majority of fruits to ripen has been used by farmers and the food industry for a long time to keep climacteric fruit more stable for shipping.  These fruits are harvested “green” before they ripen and shipped unripe since they are much firmer and much less likely to get damaged in transit.  These days, bananas, tomatoes, and other climacteric fruits are likely to be given a treatment that temporarily inhibits the ethylene response before harvest or shipping to extend their shelf life further.  Once they’re close to their final destinations they’ll either be allowed to ripen on their own or given a treatment of ethylene to speed back up the ripening process.

What we gain in shelf-life and reduced food waste we do lose in a bit of flavor.  Since the fruits are no longer attached to the plant when they ripen they don’t have the chance to transport more sugars and flavor compounds from the mother plant.  So “vine ripened” fruits do have a bit more sweetness and flavor than those that are picked green.  Having just gotten back from Rwanda, a country where bananas are a common staple food I can attest that the ones that ripen on the plant are much sweeter than those we get shipped in to the US – you know, the ones that will ripen next week sometime if you’re lucky.  There were even some in our group that don’t care for bananas here that loved the ones we had at breakfast every morning.

Grapes must stay on the vine to ripen

One possible direction for biotechnology is the engineering of plants to alter or eliminate the ethylene ripening response to reduce food waste and spoilage.  Since many genes that are responsible for ethylene production such as enzymes that catalyze the production of ethylene precursors, or proteins that serve as ethylene receptors have been identified, work is being done to develop delayed ripening by altering or knocking out these genes in a variety of crops.


Alexander, L., & Grierson, D. (2002). Ethylene biosynthesis and action in tomato: a model for climacteric fruit ripening. Journal of experimental botany53(377), 2039-2055.

Pech, J. C., Bouzayen, M., & Latché, A. (2008). Climacteric fruit ripening: ethylene-dependent and independent regulation of ripening pathways in melon fruit. Plant Science175(1-2), 114-120.

Lelièvre, J. M., Latchè, A., Jones, B., Bouzayen, M., & Pech, J. C. (1997). Ethylene and fruit ripening. Physiologia plantarum101(4), 727-739.