Are Greenhouses Ok On Septic Fields? What You Must Know


A greenhouse is a fantastic way to grow plants all year round and in any weather conditions. A greenhouse can be built from different kinds of materials and can be almost any size or shape according to your needs and available space. But, would you erect a greenhouse over a septic field?

A greenhouse can be erected on a septic field to grow certain types of plants. The greenhouse should not have permanent foundations, which could easily damage the septic system. Do not plant directly into the ground over a septic field, as the plants could absorb contaminants released by the system.

There are many online views and reviews from people who have built a greenhouse over a septic field, with varying results. While some people are for the idea, others are completely against it! From my research and my own experience, I agree that you can erect a greenhouse on a septic field, and here’s why.

Is A Septic Field Safe For Growing Plants?

When you think of a septic field, you would assume that it will be a smelly mess. After all, a septic field is where the liquid effluent from a septic tank is distributed, so surely, it should be messy and stinky!

In most cases, septic fields are not messy and are not smelly if they are constructed correctly! A septic tank is buried underground a short distance away from your house. The runoff or liquid effluent from the septic tank is drained through a system of pipes buried underground and eventually is emptied into the ground far away from your home.

The pipes serve a very good purpose: preventing the septic tank from overflowing into your yard, which would cause the smelly mess unfairly associated with a septic system. The drainage pipes should be covered with about 2 inches (5cms) of gravel and a layer of topsoil about 18 to 24 inches (45 to 60cms) deep to prevent smells.

Typically, grass is planted over the topsoil, which helps to remove the excess moisture from the soil and helps control erosion. So, if you can grow grass over the septic field, can you grow anything else? Again the answer is yes, as long as the plants you are growing don’t have a very deep root system and are not invasive.

Can You Put A Greenhouse Over A Septic Field?

A greenhouse, by design, is a method to keep your plants growing year-round and safe from the elements. The beauty of any greenhouse is that it can accommodate any growing method that you choose.

If you don’t have very much space in your yard and the area covering your septic field is the only space that you have, then, by all means, place a greenhouse on top of it to grow your plants in it.

The only restriction should be on the size and type of greenhouse that you are erecting.

Here’s a video with some more info about growing vegetables over septic:

Which Type Of Greenhouse Can You Place On A Septic Field?

When choosing the correct greenhouse to erect over your septic field, the foundations and construction are the biggest concern.

A permanent structure is not a great idea as it generally requires foundations. If you are going to lay foundations, you could accidentally dig down into the septic field pipes, puncturing them and causing them to leak.

The effluent could seep into the soil, and If you are planning on planting directly into the ground or in raised beds, it could possibly contaminate your plants.

When planning your greenhouse, consider the types of materials you will use to build the structure and how heavy the structure will be. Lighter materials would be better for a greenhouse placed over a septic field.

Also, consider the weight of the plants that you will place inside the greenhouse directly over the septic field. Too much weight could cause the ground to sag and put extra strain on the septic field pipes.

These are the best greenhouse structures to erect over a septic field.

A Semi-Permanent Greenhouse Structure

Using this type of structure requires a foundation to keep the greenhouse in place, but it does not necessarily have to be a solid foundation.

A semi-permanent greenhouse structure can be tied down with pegs and rope or simply attached to fence posts. Some greenhouse growers lay down a row of bricks or wood over the ground, place the structure on top of them, and simply peg them down.

A semi-permanent greenhouse should be strong enough to protect the plants from the elements while being easy enough to dismantle and move elsewhere when required. This structure will not place too much strain on the septic field as long as lightweight materials are used.

A Temporary Greenhouse Structure

A mobile or temporary greenhouse structure is best for use during certain seasons of the year. This type of structure can be used wherever you might need it, making it a fantastic shelter from the elements for any plants.

A temporary greenhouse is the best structure for growing over a septic field. As it is mobile, It should be constructed from lighter materials and be considerably smaller than permanent or semi-permanent structures, placing less strain on the septic field.

While a temporary structure is only expected to be used for a season or two, it can be a great way to decide if you are ready to become a grower or if the greenhouse is in the correct position for growing what you need without the expense of a more permanent structure.

If you decide that the greenhouse should not be placed on the septic field, a temporary structure is far easier to dismantle or move than a more permanent structure.

Here’s a video showing proper care of a septic tank to help with either option you choose:

How Should You Grow Plants In A Greenhouse Over A Septic Field?

If you are planting your plants directly into the ground above a septic field, never eat anything you will grow. While a septic system should be 100% safe, you cannot be sure that no contaminants have spread through the soil. There could be some contamination from the liquid effluent released from the septic tank.

Vegetables, in particular, require a lot of water and will send their roots down into the ground in search of nutrients and water. They can easily find the wastewater and absorb it and any contaminants in the wastewater. These contaminants could be transferred to humans when you eat the vegetables.

Raised beds are not a great idea either in your greenhouse, as the weight of the additional soil of the beds could prohibit the effectiveness of the septic system by adding pressure to the pipes. Also, contaminants could easily be absorbed up through the soil and into the plants.

Planting the wrong plants in the incorrect areas could lead to costly septic system repairs, so always check which plants are the best for planting in your area. Most perennials and annuals are great plants to grow over any septic field system as they won’t clog or damage the pipes.

With a greenhouse, there are various ways that you can grow anything that you would have planted in the ground. Using different growing methods, you can grow all your fruits and vegetables and still have space for pretty plants!

Try these growing methods for growing strong, healthy plants in your greenhouse.

  • Raised boxes
  • Plant pots and containers
  • Hydroponics systems
  • Aquaponics or Aquafarms

Conclusion

While growing plants over a septic tank is not a great idea, growing over a septic field is considered ok with certain restrictions.

A greenhouse allows you to grow whatever produce you need, and, as long as you don’t plant directly into the ground over the septic field, you will produce fresh, healthy plants, no matter which growing method you use.

Robert Sampson

I'm Robert Sampson and I live in Colorado where I spend a lot of time in the backyard with my family either grilling, playing games and sports, or working on a project to make our backyard a better place to be.

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