You will want to read this before you decide what to install as your hoop house floor! Learn about different ways to increase drainage and mitigate flooding issues with your greenhouse floor choices. There are a wide variety of options when it comes to flooring in a hoop house and each has its own pluses and minuses.
There are also a few things to consider that will apply no matter what type of flooring you choose. Grading, weed management and runoff mitigation should be considered before you build. Working space in front of doors inside and out should also be part of your floor planning. It will keep you from having to trudge through puddles on your way to care for your plants in the hoop house.
Keep in mind if you will be using an NRCS High Tunnel Grant that they require you to grow in ground or in raised beds no higher than 12 inches. Flooring materials for pathways may need to be approved by your local agent in order to be in compliance with regulations.
Grading for Hoop House Structures
As we discussed in our article on preparing your site for the build, we highly recommend grading the build site for your hoop house before you build. Anytime you have a slope that is more than 5° over 100 feet of length it will interfere with your build process. This is also an excellent time to plan on preparing any trenches you will need to mitigate flooding issues or standing water.
Preventing Weeds From Encroaching in Your Hoop House
Regardless of which type of greenhouse flooring options you will be using, we highly recommend installing landscape fabric along the perimeter of your structure. You will lay the fabric and secure with fabric pins and then put your ground posts in directly through it. This will control weeds, keeping them away from your edges and give you a few feet of space inside and out to avoid damaging the plastic when you weed whack or mow around the hoop house.
A handheld propane torch works very well for creating holes for the ground posts to go through. By burning the landscape fabric instead of cutting it, you get a nicely sized round hole with edges that will not fray. Make sure you are wearing thick flame resistant gloves for this step and that you have a hose with a sprayer attachment handy to put out stray flames. Check out this video for a step by step tutorial on this process. Also check out the Ultimate Guide to Ground Covers on the Farm for more information about landscape fabric.
Flooring Options for Hoop Houses
There are a few materials that are commonly used for flooring in hoop houses or high tunnels. The best choice for you will depend on your growing methods and the crops you are planning for. If you will be using some type of rock it is best to lay landscape fabric underneath to prevent weed growth.
Compacted/Crushed rock - Good surface for hydroponics, grow bags, and tabletop growing. Easy to rake and drains well. Read more about the benefits of grow bags here.
Pea Gravel - Drains well and provides a relatively comfortable working surface for hoop houses using hydroponic systems or propagation tables. Weeds can take root after a few seasons.
Soil - May need significant time before building to mitigate weeds with silage tarp and amend. Highly recommended that you get a soil test and amend before you build.
Raised Beds - Great for increasing drainage and keeping growing zones distinct from pathways. Landscape fabric and mulch can be used between beds for ease of work.
Concrete - A viable option for propagation tunnels and hydroponic systems. Can be costly and some water pooling may occur. It is also hard on your body to be on this type of floor all day.
Wood Floors - Not recommended as the wood will eventually be damaged by moisture and weeds can grow up between the floorboards.
Landscape fabric - Can be used on its own as a flooring material but it can get squishy when wet. It can also be tricky to rake out after pruning or harvesting.
Mulching in a Hoop House
If you will be using existing soil, grow bags, or raised beds to grow in, mulching your pathways will help tremendously to keep weeds down and give you a relatively dry surface to walk on and is easy to install. Mulching is allowed by NRCS grants as it helps to build soil and sequester carbon. Mulch type greenhouse flooring will need to be reapplied periodically as it breaks down.
Particularly if you will be growing in raised beds it is helpful to lay landscape fabric under your mulch to mitigate weeds. Use this method if you will be keeping the rows in the same place season after season. If you will be rotating beds or haven’t decided on your final plan for the interior you can lay fabric on the paths later. We still recommend putting fabric around the exterior before you build.
Mitigating Flooding Issues Around a Hoop House Style Greenhouse
The placement of your hoop house and the surrounding landscape will factor into what types of mitigation you will need. Starting with an even greenhouse floor surface within the house will help to keep puddling from occurring in your work space. Because hoop houses are generally high traffic areas it is good to start with the floors on the interior higher than the surrounding landscape. Adding mulch, gravel or raised beds will all assist in this process.
If your house is on a hill or in a low area of the farm you may need to plan for trenches or french drains to help with run off. French drains around the exterior of your hoop house will help prevent flooding inside the house as well as diverting runoff from the structure during rain storms. If your property has natural slopes that directs water towards your build site, you may want to consider installing some type of diversion dam to prevent water from flowing in.
Consider All Your Options and Needs Before you Choose Your Flooring Material
How you plan to grow in your hoop house as well as grant requirements and existing water issues on your farm will all inform the best choice of flooring for your hoop house. It is also important to consider working comfort and ease when making the decision. It may be that a combination of materials works best for you.
For example; you may find that having a three foot wide section of crushed rock just inside the endwalls with raised beds throughout the remaining space provides you with an easy place to store tools and move equipment around. This is particularly helpful with vining crops if you are using the Lower and Lean method. Check with your NRCS agent before you use anything other greenhouse flooring other than soil and mulch inside your structure.
Alternatively if your house will mainly be used for propagation on tables, you may find that landscape fabric and rock are better for drainage. For more permanent greenhouse style growing in containers or tables, installing concrete may be worth it to ensure your feet are always up and out of possible puddles.
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