Tag Archives: season extension for greenhouses

Season Extension: Ventilating & Heating

To make your greenhouse more of a year round functioning entity, there are two main areas in which you have to make the structure more efficient-Heating and Ventilation.

1. Heating is your biggest expense for the winter so retaining heat is a priority.

The easiest way to retain heat in your greenhouse is to install a double poly cover with air in between. A small squirrel cage blower attached to the inside layer of plastic aids in maintaining air between layers.

The more dead air space between these layers you can create, the closer you will be to achieving a 30% reduction in heat loss. Holes will result in air movement and therefore less efficiency. 3″-5″ consistent space is ideal. It is a given that you would have less then that around the edges and over the ridge.

Double plastic will have a considerably longer life span. It is important to realize that as plastic gets older, the light transmission will be reduced which will reduce production.

Infrared plastic (IR poly) does further reduce heat loss and increase light diffusion so it can also be a consideration when looking for ways to reduce heating costs.

2. Ventilation is also one of your biggest considerations for the warmer times of the year. Ventilation can be done through forced or mechanical methods or passive through vents or roll up sides.

Vents are extremely effective since they can be placed higher up where the heat needs to be expelled. Mechanical ventilation is more costly both up front and to operate but it is easier to control since it is attached to a thermostat. For mechanical ventilation to be effective, it needs to be sized and located properly.

Roll up sides are less costly and simpler to install but are restricted by the fact that you have to be there to open and to close.

Climate control is especially challenging in the spring and the fall since most days you will have the need for both ventilating and heating.

One area that you need to be especially aware of is stagnant air. Without proper air movement, circulation and exchanging, stagnant air can cause many different types of diseases. It is important to understand what your plants require

Stay tuned for the third and final installment of our series about Season Extension and Your Greenhouse coming soon!

Season Extension: Moving Your Structure

A significant part of season extension involves moving an intact structure.

This basically allows you to get two (or possibly three) plots of production from one investment.

The idea is to start a relatively cold tolerant crop very early in the season (the timing will be different in different locations).

  1. Once the crop is firmly established in location A, (and it has warmed up) you will move the structure to location B and start another crop.
  2. You will harvest the crop in location A and then after working the soil, plant another crop in location A which is intended for fall harvesting.
  3. After location B is harvested and before frost you will move the structure back to A.
  4. Instead of doing twice in location A you could also choose location C.

A structure can be equipped with wheels which will run over the soil. There is quite a bit of flexibility where you go and the terrain you navigate.

The structure can be equipped with rollers on a track. This will determine where you go and this is usually intended for moving a bigger structure with fewer people.

The most common method of moving is sliding the structure on the soil. The base rail can be wood or steel.

It is critically import to understand the logistics of moving on a structure before you start. It is not hard to move a structure but it is also not hard to do damage.

Having a plan for proper anchoring is very important for a moveable structure. Your structure is at a vulnerable state when you release the anchors. Once you start, the job must be completed quickly. You have to be aware that the anchors may not come out or go back in easily so you may need to give yourself some extra time.

One other area of consideration on a moveable structure is the ends. There must be some sort of a flap or vent along the bottom so that when a structure is being moved, the ends will not uproot plant material. Generally speaking to have this ability in the ends takes away from the structural integrity, so some extra anchoring may be required.

You can see more information and photos on our movable information page. Please don’t hesitate to call us with ANY questions you may have. This can be a very useful addition to your structure, but must be understood correctly.

Stay tuned for part two and three of our season extension series later this week!

Season Extension: Moving Your Structure

A significant part of season extension involves moving an intact structure.

This basically allows you to get two (or possibly three) plots of production from one investment.

The idea is to start a relatively cold tolerant crop very early in the season (the timing will be different in different locations).

  1. Once the crop is firmly established in location A, (and it has warmed up) you will move the structure to location B and start another crop.
  2. You will harvest the crop in location A and then after working the soil, plant another crop in location A which is intended for fall harvesting.
  3. After location B is harvested and before frost you will move the structure back to A.
  4. Instead of doing twice in location A you could also choose location C.

A structure can be equipped with wheels which will run over the soil. There is quite a bit of flexibility where you go and the terrain you navigate.

The structure can be equipped with rollers on a track. This will determine where you go and this is usually intended for moving a bigger structure with fewer people.

The most common method of moving is sliding the structure on the soil. The base rail can be wood or steel.

It is critically import to understand the logistics of moving on a structure before you start. It is not hard to move a structure but it is also not hard to do damage.

Having a plan for proper anchoring is very important for a moveable structure. Your structure is at a vulnerable state when you release the anchors. Once you start, the job must be completed quickly. You have to be aware that the anchors may not come out or go back in easily so you may need to give yourself some extra time.

One other area of consideration on a moveable structure is the ends. There must be some sort of a flap or vent along the bottom so that when a structure is being moved, the ends will not uproot plant material. Generally speaking to have this ability in the ends takes away from the structural integrity, so some extra anchoring may be required.

You can see more information and photos on our movable information page. Please don’t hesitate to call us with ANY questions you may have. This can be a very useful addition to your structure, but must be understood correctly.

Season Extension: Ventilating & Heating

To make your greenhouse more of a year round functioning entity, there are two main areas in which you have to make the structure more efficient-Heating and Ventilation.

1. Heating is your biggest expense for the winter so retaining heat is a priority.

The easiest way to retain heat in your greenhouse is to install a double poly cover with air in between. A small squirrel cage blower attached to the inside layer of plastic aids in maintaining air between layers.

The more dead air space between these layers you can create, the closer you will be to achieving a 30% reduction in heat loss. Holes will result in air movement and therefore less efficiency. 3″-5″ consistent space is ideal. It is a given that you would have less then that around the edges and over the ridge.

Double plastic will have a considerably longer life span. It is important to realize that as plastic gets older, the light transmission will be reduced which will reduce production.

Infrared plastic (IR poly) does further reduce heat loss and increase light diffusion so it can also be a consideration when looking for ways to reduce heating costs.

2. Ventilation is also one of your biggest considerations for the warmer times of the year. Ventilation can be done through forced or mechanical methods or passive through vents or roll up sides.

Vents are extremely effective since they can be placed higher up where the heat needs to be expelled. Mechanical ventilation is more costly both up front and to operate but it is easier to control since it is attached to a thermostat. For mechanical ventilation to be effective, it needs to be sized and located properly.

Roll up sides are less costly and simpler to install but are restricted by the fact that you have to be there to open and to close.

Climate control is especially challenging in the spring and the fall since most days you will have the need for both ventilating and heating.

One area that you need to be especially aware of is stagnant air. Without proper air movement, circulation and exchanging, stagnant air can cause many different types of diseases. It is important to understand what your plants require

Stay tuned for more on our series about Season Extension and Your Greenhouse including Norm’s talk at the Guelph Organic Conference, coming soon!