Plant Growth Regulators: Friend or Foe in the Garden?

Plant Growth Regulators: Friend or Foe in the Garden?

Even if you haven’t heard of Plant Growth Regulators (PGR’s) you’ve probably used them in your garden. Except they’re called by different names: boosters, rooting agents, stimulants, etc…

PGR’s are hormones that help manipulate certain aspects of a plant’s natural growth, whether it’s by stimulating the growth of roots or by making sure a plant doesn’t grow too tall.

So what exactly are PGR’s?

Plant Growth Regulators are phytohormones (fancy name for “plant hormone”) that can be given to a plant that will allow or inhibit a function of plant growth. What does all that fancy talk mean? Simply put, PGR’s are chemicals you can give your plants to have them grow- or not grow- a certain way.

Growers give them to plants when they want better, more vibrant growth and bigger, heavier harvests. Whether that’s through telling a plant to stretch its cells to grow larger or to allow cells to form dense fruit, when you give your plants PGR’s the goal is to manipulate how the plant grows.

The most common ways to apply them are either through a foliar spray or a spray/drench at the medium level. In the fruit and veggie arena, the use of PGR’s are for growing longer branches, creating and growing leaves, and rapidly growing fruit and vegetables. Common uses in ornamental growing include retarding plant height and senescence (fancy word for deterioration).

Now there are tons of different brands of PGR’s and even more combinations of each of their elements, so while we can’t possibly name them all and tell you which brands to use/not use, tomorrow we’ll go over the 5 most common PGR classes you’ll find.

Categories of PGR’s

Now it should be noted that PRG’s can be natural or synthetic, and occur naturally. For example, the PRG Triacontanol is known to make strong root structures and increase yields, and it’s found in beeswax. However, the majority of PRG’s used in gardens are derived from natural ingredients, or they’re synthesized.

The 5 classes of PGR’s are Auxin’s, Cytokinin’s, Gibberellin’s, Abscisic Acids, and Ethylenes. Each of these classes has a whole host of elements, chemical combinations, and subsequent products within them. Knowing which category a PGR falls in to will help you determine which- if any- PGR’s are good for your plants.

Auxin PGR’s are responsible for long branches in vegging plants, and in fruiting plants, they can help prevent premature fruit dropping. They can also help in flower bud development and strengthening themselves for environmental fluctuations.

Cytokinins are known to stimulate or stop plant growth. Depending on what you need, these PGR’s will either tell your plant to accelerate its growth or to slow it down.

Gibberellin’s play a role in expressing a plant’s sexual organs and functions. That means if you need to manipulate a plant’s sex or start the process of seed and pollen production, these are the PGR’s growers will use to get the job done.

Ethylene’s and Abscisic acids are used to slow down growth and slow down cell deterioration. They also inhibit branch growth, so these will tend to keep your plants nice and short.

Should you use PGR’s on your plants?

So are Plant Growth Regulator’s good or bad? Well, that’s a little bit of a tricky answer. Let’s face it: when it comes to PGR’s there’s little we can do to avoid them. If you purchase produce in a supermarket, chances are the majority of it has been treated with PGR’s. Lots of medicinal flowers- especially grown in big quantities- are treated with them to get bigger, heavier harvests, too. But in the pursuit of healthy produce and consumables, we believe the use of PGR’s should be taken very seriously, and frankly, the majority of them should be avoided on certain plants.

First, use an extremely minimal dose in relation to your plant count. PGR’s need to be heavily diluted because too much of a hormone will quickly ruin the plant.

Second, heavily research the hormone(s) you plan on using and their effects on your plant. For example, if you use a PGR that speeds up fruit growth, make sure it won’t grow the fruit too quickly or else the fruit will ripen unevenly.

Third, we suggest avoiding a foliar spray on crops you plan on consuming. Especially important for fruits and vegetables with thin or soft skins, you don’t want to consume something that has chemicals soaked into it, because there’s not much you can do to flush them out if they’ve already soaked in.

Last, and most importantly, we suggest avoiding using PGR’s if the goal is to fix mistakes in the growing process. From fruits to veggies to flowers, consumers can tell when something looks better than it actually is: big fruit that tastes terrible, vibrant plants that smell funny, or in extreme cases misuse of PGR’s can result in illness.

If you choose to use them, consult a professional who uses them first and make sure they’re sustainable in your garden. Otherwise, training and experimenting with growth, nutrition, genetics, and some patience will get you the crop you want.

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