Can greenhouse be too big?

I think there are many factors to consider in that decision:

• How much time are you able to dedicate to plant care?
• How automated will the control systems be?
• Can you afford the utilities?
• A larger structure will be more stable in its conditions.
• Your control systems dictate the environment far more than do the plants.
• A larger structure may allow you to have "climate zones".
• Growing plants spaced apart is better than bunching them up.
• Equipment (heaters, fans, RO systems, tanks, pumps, etc.) take up space, and need to be easily accessible for maintenance and repair.

I had between 750 and 1000 plants in a 300 square foot greenhouse. It contained a fogger on a humidistat, fans that ran 24/7, thermostatically-controlled ventilation, and thermostatically controlled heating. There was an RO system, a 150 gallon storage tank, and pressure pump connected to the fogger, and to irrigation (hand and automated) after an injection pump added fertilizer. Over the years, I was able to "fine tune" my potting/mounting such that I could water everything at once, amd that allowed me to automate that, using remote control or timers to manage an overhead "rain" system. Had I wanted to, I could have left the entire thing on "automatic" for weeks.

I spent about $4000/year on propane for heat, in southeast Pennsylvania.

I'd have given my eye teeth for more space, though....

 

The rain system was nothing but a network of 3/4" pvc pipe into which I inserted spray nozzles, and it was turned on or off via a solenoid valve controlled either manually by a remote system I built, using wireless technology akin to garage door openers, or automatically with a lawn irrigation timer if I was going to be away.

I don't know where you live, but as someone who has been selling RO systems for 20 years, I don't recommend that they be outdoors, as temperature can have a huge impact on their efficiency, not to mention UV degradation.

I'm not sure what your concern is about "large and empty." The closer you come to a geodesic dome in shape, i.e., a square foundation versus an elongated one, the more energy efficient it will be. Besides, greenhouses, in my experience, don't stay that way!

I don't know if you can do so, but if you can sink the floor of the GH into the ground, it'll add thermal stability, and energy efficiency. If I could, I'd go 4' deep. I saw one once that was 8' deep, with only the roof being glazed, and it was an awesome environment.

As to temperature zones in a greenhouse, I think you'd be surprised how effective a few plastic sheets can be at stratifying stuff. Assuming a central aisle, floor-to-ceiling sheets creating a "wall" of about about half- to 2/3 of the total width can create a significant temperature difference between the end with the heater and that without.

The vast majority of my plants were paphs in 4.5" or 6" pots, but I had stuff in thumb pots, on twigs, etc.

 

The only drawback I can see is that, depending on where you are situated, it would cost more to heat up your greenhouse.

 

Even with the considerations of cost, time, etc., nearly every serious "Greenhouse Orchidist" I've met has said they wish they had built a bigger greenhouse! Empty space as Ray indicated is not an issue for long and we have running jokes in our local society on where we ask publicly "how long did it take to fill your greenhouse"? I am on my third greenhouse. The first two were in that 200 - 300 sq. ft. range and the current and maybe last is 1800 sq. ft. I have a wall in the middle and half is heated for intermediate/cool orchids and the other half (for seasonal crops) is heated to just stay above freezing. And I've started to encroach on the the other side with Orchids that like cold dry winters .

In my bigger greenhouse...when it was empty, I did have issues with little Pleurothallids so even built a little enclosure with a fogger to give them the humidity they needed. Now with a full greenhouse and improved controls over the years, I can grow and bloom many cool growing minis that require high humidity right in the open. I am thinning out my larger plants to be able to grow more minis. I do find the climate stability of within the larger space is a plus and also finding the unique microclimates to accommodate different types of orchids as well. My biggest concern with my current greenhouse is not whether I can maintain it now, but what about 10 years from now?

 

Hi Daniel... Have you started your greenhouse yet? One thing I wish I had more room for is hanging carousels! Marnie has many of theses in her greenhouse (full length) and they are the best way to grow mounted plants... (Plus I have some friends who hang net pots on there carousels, great for Dracula's!) It seems like you're growing lots of miniatures and if they are mounted this is the way to go... I'm growing more and more mounted plants and they are much happier than grown in pots! Living in Santa Barbara you have fantastic growing conditions and many great growers live in your area!

Having a tall, large greenhouse you will have better control of the high and low temperatures too! I have never heard anyone ever say they built there greenhouse too large!!!

Dexter

 

I have a hobby greenhouse 20 by 12 with a 9 ft peak I have some 200 plus orchids All types of genera I know after about 8yrs of using this greenhouse I probably gone a little smaller Since the beginning I've had extra growing space which I quickly filled up depleting my bank act in the process I studied in horticulture and worked in the greenhouse business prior to owning my own hobby greenhouse In terms of heating it is easier to heat and hold temperatures in a larger structure than it is a smaller structure due to the plants themselves help to store the heat as well as the air space and ground area and temperatures and humidity levels do not fluctuate as widely in larger greenhouses
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