How To Keep Grass From Growing In Your Greenhouse

Before you get stressed on how to keep grass from growing in your greenhouse, remember prevention, sanitation, and herbicides are the solution. These three simple factors before, during, and after the problem will keep your greenhouse grass-free, and your plants will be happy too. And let’s face it, a greenhouse with many blades of grass growing inside is unappealing to the eye. 

Before one venture in greenhouse gardening, they must know about the various elements that play a role in the greenhouse’s success. However, not every article out there talks about potential problems and how to manage them. If you start seeing grass or weeds in your garden, don’t panic because preventing and solving them is simple.

How To Keep Grass From Growing In Your Greenhouse

How To Keep Grass From Growing In Your Greenhouse Complete Guide



According to the University of Massachusetts Amherst, the first step for managing weeds in the greenhouse is by preventing them from happening. To do this, you must understand where they come from and avoid these instances beforehand. Unless you specifically cultivate grasses in the greenhouse, these weeds create an unsightly greenhouse, compete with your crops, and attract pests and diseases.


Mowing and herbicides

The easiest way to prevent grass in the greenhouse is by ensuring that your growing media and plant materials are free of weed seeds and seedlings. Additionally, when you start seeing grass around your greenhouse’s vicinity, you must immediately address them using herbicide or mowing. A common mistake of a gardener is ignoring weeds unless they already grow inside the greenhouse, but controlling them while they’re still small will save you the hassle later on. 

It will be harder for you to control the weeds if you let them flower and set seeds because they can germinate for many years. If you don’t see any weeds close to the greenhouse, then grass management should be easy for you. Check the areas between your greenhouses, irrigation pounds, or outside the vents as weeds tend to thrive in these places. 


Weed blocks and yearly solarizing

The Center for Agriculture, Food, and the Environment in UMASS also recommends physical barriers like weed blocks to prevent weeds in the greenhouse. It can be a landscape cloth topped with gravel to keep grasses from growing underneath. Lastly, yearly solarizing of an empty greenhouse can also help you address weeds early on. 

If you have time in the summer months, you can close the greenhouse vents to create a hot and dry environment that will deter weed growth. 



Frequently, the seeds and seedlings are already present in the things we use in the greenhouse, so sterilizing everything before bringing them indoors should be a mandatory practice. Did you know that sanitation and cleanliness inside a greenhouse plays a significant role in preventing and controlling grass in the greenhouse? A clean greenhouse floor and the potting area will prevent weed seeds from germinating, so always do a sweep indoors. 

Some ways and practices introduce weeds or even encourage their growth. For example, if you utilized previously-used pots without cleaning them thoroughly, this opens an opportunity for weeds to enter the greenhouse. The same goes for reusing growing media because you’re trying to save on costs, however, in the long run, your expenses will be higher from controlling and removing weeds and addressing diseases. 

Cleanliness and sanitation also come with checking your storage areas because they can also harbor weed seeds. Racks, bulk goods, pallets of mix, walkways, and benches are things and areas we overlook in the greenhouse, but weeds can infest them. Pallets of mix with damaged packagings can encourage weed seeds to grow inside as well. 




Herbicides as your last resort

Using herbicides in the greenhouse is more complicated than the previous methods mentioned. It’s worth mentioning that it’s crucial to understand and obey the instructions and restrictions in the herbicides, especially if you’re growing vegetables. There are even federal laws on the use of pesticides, as mentioned by the University of Minnesota Extension

With herbicides, it’s more advisable to use it in non-growing areas rather than inside the greenhouse. There are pre-emergence and post-emergence herbicides, and understanding their proper uses and precautions is a must because of the risk in damaging plants. For example, pre-emergence herbicides are best for controlling weed seeds, but they also pose a threat to your crops because they are volatile. 

Another reason why herbicides are not easy to use in a greenhouse with plants is because of the condensation that can occur. However, if it’s too hard to address heavy weed infestations, you might need to use post-emergence herbicides. This will be your last resort and only applicable if you removed all your crops and have read everything to protect yourself.



Prevention, sanitation, and herbicides are your answer to how to keep grass from growing in your greenhouse. However, precaution and diligence are necessary for using herbicides because they work best as your final resort in addressing weeds. To keep grass from your greenhouse, simple practices in prevention and sanitation are enough. 

Constant scouting of the area around the greenhouse, mowing, sanitation, and cleanliness will help you avoid grass infestation. These simple practices should be included in your daily duties in the garden because the sooner you address weeds, the easier it will be to stop them. 

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