by Adrian White
20 December, 2021 by
Lucija Johum

Greenhouse owners have a lot to get gung-ho about: switching to greenhouse growing brings many advantages to your business or hobby. Still, there’s a lot to get right at the very beginning to best experience these advantages: such as how to transition to covered structures smoothly, and to even make sure you’re selecting the right materials before you get building.

One of the biggest first steps is to also ensure that you’ve chosen the perfect location to put your greenhouse. Important to this process: prepping the actual land and site upon which you want to build to make it fit for building, and for your operation in general. Depending on the type of greenhouse you want to build and the site you’ve chosen, site prep might be easy – while in other situations, it can be quite the task.

Study the site and ask yourself about some of the following topics in this article, along with how you want to go about making them work for you and your soon-to-be-built growing structure. This includes how you’ll erect your building to be level, how it will drain, and many more subjects besides. These are good to wrap your head around – and long before you build!


Laying a foundation? Are you using anchors, ground posts, rebar, or needing to dig for any reason at all? Then you’ll want to check your backyard or property before you dig, especially if you’re close to an urban or municipal area.

More specifically: you’ll want to make sure that you don’t strike any underground cables, water lines, or sewage lines beforehand (not only can this be a mess – it can be life-threatening!). So before you pull out the shovel or backhoe, make an 811 or similar call for the area in your state where you are building. Areas of concern will be marked by appropriate waste and electrical companies over the next few days so you know where they are – and if they happen to be right by or within your greenhouse building site, then you may have to move your plans elsewhere.


Around the same time you contact 811 to check out what may be underground, also make sure to look into the site’s zoning before you build or prep your site. It usually doesn’t pose a problem, and your greenhouse can continue to be built uninterrupted – but zoning laws (and thus building codes and the right permits) may shape or change the way (or where) you build your greenhouse into something different from what you expected. If any zoning or codes apply to what you want to build, you’ll want to know, especially during the site prep phase.

Why is that? Here’s an example: you wouldn’t want to build a fully functional, expensive, and sophisticated greenhouse on your property, only to find out that the land is zoned against any agricultural use. Further, you’ll want to know if there are building codes related to zoning that designate the size of what you can build and where. Not knowing all this can be a huge headache down the line – requiring some greenhouse builders to make changes to or even take down their entire setups completely.

While chances are greater that you won’t run into these problems at all, you won’t want to risk the expensive consequences (and the ultimate frustration and cost) of not knowing them, if they happen to be there. For that reason, make an investigation into zoning and building codes a part of your site prep checklist. More likely than not you’ll be good to go – otherwise, you can adhere to the changes officials will require of you to deem your structure legal and safe, and continue your greenhouse project uninterrupted from there on out.


Contrary to any fanciful plans in mind, you can’t build a greenhouse on unlevel ground. Slopes and hills are out of the question for issues relating to drainage and proper sun exposure. However, if you DO want to make your structure work on that hillside, you can certainly make the spot level for construction – though it will take some extra work.

Keep in mind: if you’re building on a relatively flat lot, you won’t need to make it absolutely and perfectly flat; just generally flat will do. But for a hillside or slope, it may be time to pull out the trenching shovels (or even bulldozing equipment) to carve out the flat space you need. If shrubs and trees are another obstacle, you’ll have to enlist some root or stump removal to get the space fully cleared and usable.

Levelness comes into play at varying levels of importance depending on the greenhouse growing or planting technique you plan to use. For example, you’ll want to make things as level as possible if you are using growing benches or tables, hydroponic systems, or setting up a foundation-laid structure or retail commercial greenhouse for nursery plants that customers will enter. However, if you’re direct planting into tilled or worked beds under your structure, levelness certainly does not have to be perfect.


If you’re not planning on using any foundation but still desire an appearance of uniform flatness, consider a sturdy ground cover. This will be less expensive than investing in a concrete foundation and can be just as pleasing to the eye, if not surprisingly sturdy. Consider it a more affordable alternative in greenhouses where you are selling nursery plants, container gardening, or even a hydroponics system.

Under greenhouse structures where you want to keep things neat and tidy, ground cover is very important especially for keeping weeds down. You can wager a bet that, no matter how much you clear or level an area, there will be residual seeds that sprout and rear their pesky heads. On that note too, ground cover may be of benefit not just within the actual structure, but around some of its outsides as well to create easy access to the structure.

Also be conscious of the color of your ground cover, if it counts. A black ground cover will absorb and generate heat, which may be overwhelming to some varieties; while a white ground cover may be gentler for heat-sensitive plants. Most ground covers come in a black color, however, and don’t pose an issue.


Wanting to go all the way with a greenhouse foundation? Especially for the most professional, frequented greenhouses (especially by customers), having a concrete floor will give your setup a clean aesthetic, with a touch of class. Having a foundation and concrete floor may also be of most interest to you too if you plant on using growing benches or hydroponic flood table systems.

Some greenhouse builders have enough knowledge to pour a foundation, though if you want it done correctly and professionally (guaranteed), it helps to enlist a contractor who’s done it time and time again. And again: if foundation requires digging or staking, make sure to make your 811 call. Further, greenhouses with a foundation are also considered permanent structures, and could be subject to stricter building codes and zoning laws – make sure to check these first and get the permits you need before building (or pouring!).


Most growers will be wanting to irrigate their greenhouses. So when tackling site prep, you’ll have to keep in mind during this process of where you’re planning to have all that water go – and in a way that is beneficial not only to your operation, but to the surrounding environment, too. Without a drainage plan in place, your plants may be subject to all sorts of problems: excessive moisture can lead to disease, while runoff and flooding can have a negative impact on your soil mediums.

If direct planting into the earth under your structure, drainage strategies may have to be met with potential drain tiling, or positioning your site on an intentional slope so soils do not become waterlogged. If investing in a groundcover, consider overlaying your prep site with a layer of gravel, which helps prevent water pooling and eases natural drainage back into the water table.

If you’re considering a foundation and irrigating under the same greenhouse structure, then a more sophisticated drainage system will have to be set up: such as pipes or drain tiles that run out from underneath the building. A drain hole in concrete may have to be installed, too. Otherwise, buildup of water and moisture can lead to cracking foundation, soil loss, plant disease, pest population increases, and even more issues for your system.

Last but not least: when prepping your site and thinking about where drainage will go, consider the surrounding environment. You won’t want drainage (especially if you apply chemicals) to go into a nearby river, pond, or wetland; or even into a neighbor’s yard or adjacent area. Further, the way you handle greenhouse drainage can play into the zoning laws that apply to your structure – nearby conservations may legally demand that you have a way of dealing with runoff or drainage so it doesn’t pollute or negatively impact the environment.


As they say in any building situation: make sure your foundation is sturdy before you build anything on it. The first layer of your structure will affect everything else about it, even in the case of greenhouses: a proper site preparation is the best way to ensure a resilient overall structure. Even if you don’t lay a solid foundation of concrete in the end, the actual site where you are building must be smartly prepared and chosen – otherwise, you may experience unwanted obstacles later on.

Use foresight when prepping your site. Is it level enough? Where will water drain away into? Can I build a foundation here? What sort of needs do my plants or growing system have from a site, and do I need to make it perfectly level or install a ground cover?

There are tons of details before prepping your building site after choosing the perfect building location. Take all of them into consideration, and be prepared!

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Lucija Johum 20 December, 2021
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