How to Use Rapid Rooter Plugs, the “Right Way”

Any gardener worth their gloves has seen the various kinds of grow plugs floating around the market, which are sold under a number of names other than “grow plug”. In fact, General Hydroponics takes home the Blue Ribbon prize for Catchiest Name, due to their “Rapid Rooter” line of products. Despite grow plugs being around for decades, General Hydroponics demonstrates how a clever name for a quality product can breathe new life into old tools.

What is a “grow plug”?

“A cylinder of medium in which a plant is grown. The term is generally used to describe seedlings and rooted cuttings which have been removed from the container but with the medium held intact by the roots.”

– Grow plug definition according to the ANSI Nursery Stock Standards, published by the American Horticulture Industry Association.

So a plug is basically the clump of dirt packed around the root ball of any given plant, although most often refers to young plants that are being transferred from a starter location to a more long-term one. 

A grow plug like Rapid Rooters is technically a polymer-bound plug, meaning the growing medium is bound together by a polymer. This gluing of the medium keeps enough of it intact to provide the seed with what it needs to germinate and root-in.

How to germinate seeds in Rapid Rooters

Polymer-bound grow plugs became incredibly popular with commercial nurseries due to their efficiency, ease-of-use, and cleanliness. This leads to a more effective economy of motion in the commercial greenhouse, which translates directly to productivity gains.

It didn’t take long for homegrown hydroponic horticulturists to realize why the commercial sector relied so heavily on starter plugs, plug trays, and tray warmers for successful germination and cloning. Plug trays allow for dozens of seeds to be germinated, sprouted, and rooted-in all at once, and in one convenient location.

There are several different methods of germinating seeds, but as long as a healthy seed is provided with three main things, it will crack open and begin to grow. These three are:

  1. Darkness
  2. Moisture
  3. Warmth

Therefore, an ideal germination setup would include the Rapid Rooter starter plugs for darkness, placed in a plug tray for maintaining the medium at the proper moisture, with a warming mat to incubate the plugs and catalyze, or at least expedite, the germination process.

General Hydroponics Rapid Rooter Tray, 50 cell tray & plugs

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This General Hydroponics Rapid Rooter starter tray can be used to germinate up to 50 seeds at once, via the Rapid Rooter plant starters. The growing medium in each starter plug is a proprietary blend of organic material that is polymer-bound with plant-derived polymers.

These starter plugs are also fortified with General Hydroponic’s micronutrients, which are among the best-known and most commonly used in hydroponic gardening of all kinds. Rapid Rooters are engineered to maintain the optimal air-to-water ratio when properly moistened within the Starter Tray.

Includes: (1) 50 Cell tray and 50 starter plugs

Dimensions: 19-½” length by 9-½” width by 1-½” height

General Hydroponics Rapid Rooter Plant Starters, 50 Plugs, Black

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Seedling Trays – MIXC 5-Pack Seed Starter Tray – Propagator Kit with Humidity Vents 

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This vented propagator kit is perfect for cultivating entire trays of plants from seed to sprout. The vents allow for more precise control of humidity inside the propagation chamber, while the bottom pan serves as a drip pan. This propagation chamber will allow you to keep your grow plugs at the right moisture content by letting excess drip through the plug tray and into the drip pan. 

This 5-pack of vented propagation domes is a great deal for beginners just getting their equipment together, as well as savvy hydroponic gardeners that know you can never have too many of these trays around. With these boxes, you are transcending the uncertainty of throwing a few seeds in a hole and hoping for the best, and instead gardening with precision.

VIVOSUN 10″x20.75″ Seedling Heat Mat and Digital Thermostat Combo Set MET Standard

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Speaking of precision, this outstanding product from VivoSun seals the deal, for real. Used in combination with a vented propagation chamber and a high quality grow plug like Rapid Rooter, you can fine-tune the chamber’s humidity vents to find the “sweet spot” of retained temperature and humidity. 

People often get a plug tray and the included grow plugs, plant their seeds, and add water, assuming that heating pads are optional. After all, agrarian societies got by for a long time without such new-fangled niceties. The truth is, however, that the warmth provided from a heating pad acts as a catalyst to germination, meaning it either triggers it to begin or assists the process. 

The heating pad generates heat that is basically free energy for everything buzzing around at a microscopic level. Moisture evaporates and condenses more readily, providing circulation of micronutrients throughout the isolated environment, and the warmth compels the seed into sensing enough safety to open its shell and emerge.


What are rapid rooters made of?

Rapid Rooters are a polymer-bound grow plug manufactured by General Hydroponics, a major producer of hydroponic growing supplies and proprietary hydroponic nutrient blends. The Rapid Rooter grow plug, specifically, is made from a unique matrix of peat moss and plant-derived polymer binders. This medium and polymer combination has demonstrated an optimal air-to-water ratio within the plug’s matrix, most commonly resulting in explosive early root growth.

Do I need to soak rapid rooters?

While there are quite a few techniques floating around, the short answer is yes, you should soak your Rapid Rooter plugs in cool, distilled water before seeding. Some growers opt to soak their plugs in a weak nutrient solution before planting any seeds, although brand-name Rapid Rooter plugs come pre-fertilized and make this unnecessary.

There is similar disagreement on the length of time that the plugs should soak for, with 24 hours being the standard, arbitrary recommendation. That being said, pre-soaks lasting only 1-2 hours have been reported with positive results, so that may very well be the minimum. 

What’s important is that the water itself is cool or cold, which you can think of as simulating the last frost in the soil. Really what is happening is the cold water is permeating the grow medium without dissolving the polymer binding of the plug itself. In any case, you’ll want to let the plugs drip-dry to being moist throughout germination, so excessive soaking is only liable to wash away any existing micronutrients in the medium.

Do rapid rooters have nutrients?

Rapid Rooter grow plugs contain a peat moss substrate that is, according to the packaging, chemically and pH inert. This means that it has no nutrients or pre-fertilizers beyond the naturally occurring micronutrients available in any organic substrate.

Some growers work around this by using a weak nutrient solution for the initial soaking of the plugs. This effectively loads additional nutrients into the plug to insure their immediate availability to even the youngest roots that emerge. 

How wet should rapid rooters be?

When people report that their plug-germinated-seed failed to “pop,” or crack open and sprout, it is usually due to overwatering. After soaking, the plugs should be placed into a plug tray with drain holes that allow excess moisture to drip free. 

Placing the plug tray into a suitable propagation dome will help ensure that the excessive runoff will contribute to the humidity of the chamber, ensuring a more even distribution of moisture. 

If you don’t have a propagation dome, you can still use Rapid Rooter plugs to germinate seeds into healthy plants. There are all sorts of resourceful ideas out there, like poking holes in ice cube trays and using a bin, bowl, or tin to catch the runoff. Just provide the plug support on all sides and the ability to drain freely and it will work just fine.

You’ll want to water the Rapid Rooter plugs often enough to keep them moist, or above 75% saturation.

Do rapid rooters go bad?

Rapid Rooters are chemically and organically inert when packaged, but they are still a grow medium that is specially designed to improve early growth performance. That performance will translate to anything that inoculates the medium, meaning mildew, mold, and other forms of “rot” can take hold if the plugs are stored improperly. 

Proper storage essentially means keeping them in their packaging until you are ready to use them. Any unused portions should be handled as little as possible, and transferred to a sealable bag (like a Ziploc), adding a small amount of purified water if desired. Keep them in a cool, dark place like a drawer, tote, or cabinet, and they can easily last 3 years or more.

Can you rehydrate rapid rooters?

Rapid Rooters can be rehydrated – to a point. The polymer-bound substrate has an initial texture that is much like a sponge. While moist, the physical matter of the medium is flexible and resilient. Once it has dried out, however, it becomes much more brittle on a microscopic scale. The breakage is on such a small scale that it can directly impact the bonds between the polymer and the medium, meaning that even after rehydration it fails to achieve the same texture.

You can keep your Rapid Rooters nice and moist by storing them in an airtight container, like a Ziploc bag. If you push the air out of the bag you should be able to see a layer of liquid as well – if not, add a tablespoon of clean water.

Are rapid rooters organic?

Rapid Rooters are organic, in the sense that they are made entirely from natural components and carry forward no trace of chemical or genetic alteration in themselves, nor in the plants grown in them. Rapid Rooters are not certified as an organic product, but as a rooting sponge, there is no requirement or even expectation for such.

Rapid Rooters are, technically speaking, organically inert in every viable way. For example:

– The plugs are non-soluble in water

– The grow medium has a 0.0 pH (acidity/alkalinity)

– The substrate itself is peat moss and plant-derived polymer

Rapid Rooter starter plugs are ideal for organic gardens where the origin of grow medium and fertilizer is of concern. These plugs can be transplanted into both soil and soilless systems after rooting.


In conclusion, it seems that closer scrutiny only served to reinforce the good things we’ve already heard about Rapid Rooter plugs. These plugs have a reputation for seeing plants exhibit explosive root growth, especially in the early stages.

This can make all the difference in the world in a nursery or commercial greenhouse where the time from germination to harvest can directly impact profitability. Just as important is being able to identify the healthiest plants early on, as many gardeners germinate more than they need and cull the weaker plants from the garden.

Whatever your technique and whatever your garden, Rapid Rooters is the kind of product that can easily find a place and make itself useful. Let the kindergarten teachers stick to the paper towels and dixie cups, and introduce yourself to one of the most dependable shortcuts to a green thumb that money can buy.

We hope you found this look at Rapid Rooters grow plugs to be helpful and informative. We encourage everyone to stay healthy, stay safe, and stay growing! Thank you for reading – we look forward to seeing you again soon.

High Tech Gardening