Green houses/ hoop houses are becoming more and more common. You can even qualify for grants to help purchase a hoop house from the government. You have to check with your local NRCS contact EQUIP program and your local extension. I am going to focus on why we chose to build one. Why we chose to build it the way we did and some of the issues we have discovered. In the first year.
To begin with we looked at where we live (south eastern Iowa) so we can have pretty cold and windy conditions. On average we are around a 4 with gusts in the 6/7 range. This would preclude us from being interested in anything that was not anchored well. This would also cause us to consider not having a large vertical face.
As you can see below we have a .25 mile lane and lots of open spaces around our little oasis. The openness allows for a great unobstructed growing day. However the lack of wind protection is a concern not only for the green house but for growing and living spaces in general. Being surrounded by mono culture crop land we thought may actually increase pest pressure in a PORT affect. Whereby our space can provide habitat for pests that is not available in the surrounding area which could affect our plants both in and outside of the green house.
Do you need a green house to grow veggies and other produce in our area? The answer is a resounding NO! But, you can grow more longer and higher yields with a protected environment. Elliot Coleman has shown that with appropriate planning you can grow 4 seasons in Maine. Which is further north then we are. As a matter of fact you should take a moment and look at your latitude. We are at 41.3 degrees which is at the same level as Spain, turkey, Greece, Italy (Sardinia) to name a couple. Wiki 41st Parallel Which all have a history of long growing seasons. So without adding lights we can count on being able to produce year round. The concern becomes temperature. We can expect significant more cold then Sardinia for example. However that can be negated with both heated and unheated green houses without additional lighting.
Knowing that we are cold enough to have concerns for year round growing and knowing that we need to be concerned about the materials and shape of any growing structure we utilize. So what are the options for green houses?
The first is a very commonly found at your big box stores. It is made of thin plastic or metal. The panels are thin and prone to breaking. It is not anchored to the ground. Nor will it hold up to any sort of long term usage you will have minor damage after the first year of regular use in our environment.
The second is a basic hoop house. It most likely has dirt floors and this version does not look to have roll up sides or direct ventilation. Dirt floors are useful for growing a larger variety of produce. Concrete floors allow you to manage weeds and pests easier. It allows for a cleaner work area and with the addition of tables may make for a more ergonomic growing. The main downside to concrete floors is increased costs and increased reliance on artificial media to grow in. NRCS does not allow (as far as I have found) concrete floors in our area you must grow in or on the bare ground. The roof is rounded which helps with shedding rain water but could be problematic in a heavy snow event.
The third is a commercial hoop house. This has roll up sides that allow for more ventilation. A Cathedral roof allows for more snow shedding then a more rounded shape. The floors may or may not be dirt and the structure can be heated or not. This size would allow 4 seasons of production on a market scale.
The forth is a fully commercial greenhouse and as you can see is actually multiple smaller structures joined together. It is most certainly heated and is more certainly concrete floors. The cost of the structure would require it to be built and utilized year round producing high value products that can be grown in various media and technologies think Hydroponic tomato or lettuce.
The fifth is a geodesic dome. Most commercial and hobbyist stay away from it for a variety of reasons. The most obvious is the wasted space. There is a lot of vertical space that cannot be used unless you are growing something like trees. The roundness also prohibits you from “stacking” the structures as you can see in number 4. They are efficient in energy usage and resource allocation.
The sixth is a walpini which is what I consider the artisan greenhouse. These are site specific as if you are not careful you can shade your growing area out for most of the year if you are to far north. They have a high thermal mass being most buried and therefore are extremely energy efficient. They are not for the hobbyist as they are labor intensive to construct.
I added the last two so you can see that there are many options to choose from when you picking what you need. So we know that we need something that can be anchored. We want to grow in ground of the cost savings and the ease of technologies for dirt working. We also want it to be structurally robust so no film we want clearn panels. So we decided to take a modify a design similar to the 1st one.
The next blog will show you what we did and describe why we did some of the things we did. Till then…