Weeds in My Greenhouse? Say It Ain’t So!

By Shannon McKee
Published: March 29, 2019
Key Takeaways

When it comes to greenhouse growing, weeds are still something horticulturists must deal with and eradicate. Shannon McKee shows indoor growers how to stamp out weeds and keep them from returning.

Your greenhouse is the perfect environment for growing all types of lovely plants. Some of us use our greenhouses to extend our growing season so we can grow through the spring and fall, and in some setups, even get fresh crops in the winter. Others use their greenhouse to grow plants that are more exotic than what they can grow throughout the year. No matter how you use your greenhouse, it’s not just the perfect growing environment for the plants you want. It’s also a perfect growing environment for weeds. Some may have this misconception that growing in an enclosed environment means no pesky things like insects or weeds. The truth is you can have problems like weeds. Let’s go over how you can abolish them from your greenhouse once they’ve taken hold, and what steps you need to take to prevent them from getting a foothold again in the future.


Handling a Current Weed Issue

Your first impulse may be to purchase a weed killer and go whole-hog on killing off all of the weeds in your greenhouse. This attempt may be the quickest way to kill the weeds in your greenhouse, but it could also damage the crops you’re intentionally growing. The most optimal way to handle greenhouse weeds is the old-fashioned method of pulling them out completely using a weed puller. You’ll definitely want to make sure you pull them out roots and all as they can come back if you don’t get the entire root. This effort can be backbreaking work, but the result is worth it.

Herbicides — Natural and Chemical

If you do turn toward a natural or chemical solution, be sure to find one that fits your needs and carefully follow the directions. Some herbicides are specially formulated to be used inside a greenhouse, so it can be helpful to find one that’s labeled for this purpose. Spraying it all around your greenhouse will probably result in other plants being hit by the weed killer. There are some weed killers on the market that are intended to be used against specific plants where you apply a gel to the leaves of the plants you want to be eliminated, and this may be a better option for your greenhouse if you’re being overrun.


Stop the Seeds Before They Start

You want to try eliminating greenhouse weeds before they go to seed. If the weeds have gotten to this point, you’ll have to deal with weeds a lot longer than just handling the visible ones.

Preventing Weeds in the Future

There are several things that you can do to prevent weeds from taking hold down the road.

One of the key ways to prevent weeds in your greenhouse is to keep track of everything that comes into your greenhouse. You want to use clean media that’s not going to be contaminated with weed seeds. Taking soil from other areas of your garden or yard may mean you’re introducing seeds into your greenhouse.


It’s also important to control any weeds in the surrounding area of your greenhouse. Having tons of weeds outside will eventually cause their seeds to make their way into your perfect growing environment. Keep in mind that if you use herbicides outside of your greenhouse to handle this growth, be sure to protect the plants inside of your greenhouse by closing vents, windows, and other openings to prevent it drifting inside.

You may even find it helpful to use weed barrier cloth inside of your greenhouse. If you have a dirt floor, apply it to the floor in addition to your growing beds. A weed barrier may seem like overkill, but it can be helpful.


You’ll want to monitor any newly potted plants you bring into your greenhouse in the future. There’s the possibility they may be harboring weeds. As soon as you notice anything additional growing with your new plants, you’re going to want to take care of it.

Additionally, you’ll want to wash anything that had dirt in it if you’re planning on reusing at a later date. This washing will remove any weed seed residue in addition to other potential problems that were in the soil. Stop the comeback before it starts. Don’t stop at just washing your pots and other growing containers. You should also be cleaning and sanitizing your gardening tools, as well.

Vigilance is Key

No matter how you work to prevent weeds in the future, there’s always the possibility of them making their way back into your greenhouse. If you become lax in checking for weeds, they will take the opportunity to start thriving again. Haven’t you ever noticed that where there was a single weed one day, several more appear in no time? You want to catch weeds early on, so vigilance is key to keeping them out for good.

Weed control is something you can’t neglect in your greenhouse. You don’t want to end up having to deal with weeds when you could be doing what you love and just growing your favorite plants. Take care of the weeds you have, and work towards preventing them in the future.


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Written by Shannon McKee | Freelance Writer, Gardener

Profile Picture of Shannon McKee

Shannon McKee lives in Ohio and has been a freelance writer for several years now, including on her blog, Nicknamed by loved ones a garden hoarder over the past few years, she grows a wide variety of plants in her urban garden.

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