BROMELIAD Rest Period???

[Dihcro]

Just curious if pineapples (they are a type of brom) need rest periods? Like a break from lighting... Let me explain. I'm working on a project to build a greenhouse for pineapples, but I live in a climate with a big temperature swing from summer to winter. I'm designing the heating system for the greenhouse. It's a very simple, polyethylene-cover greenhouse. I was given the idea to hang a few light bulbs from the top of the greenhouse at night to keep the air temperature warm. I have soil heating planned out already, so that's good to go. Just want to raise the temperature of the air in the winter. No heating is needed in the summer.

I can't find any "experty" info online about pineapples, and since they are a type of bromeliad, I just assumed they would have kind of the same lighting situation and stuff.

It's only going to be a few light bulbs in the middle of a pitch-black night. Would changing the color of the light bulb change the amount of light being absorbed by the plant, whilst still creating the same amount of heat?

[Ray]

The answer to the color temperature is "yes", with green being relatively unused by the plant, but I really doubt that "a few light bulbs" are going to provide sufficient heat, and soil heating is inefficient for heating the greenhouse, and are especially ineffective for plants that don't have very extensive root systems in the first place.

If you'll provide the following info, I'll work up an estimate on the size of heater you'll need:

Total surface area of the greenhouse covering.
What, specifically, will it be covered with?
What are your all-time expected winter lows?
How warm do you want to keep it?

[Dihcro]

Originally Posted by Ray

The answer to the color temperature is "yes", with green being relatively unused by the plant, but I really doubt that "a few light bulbs" are going to provide sufficient heat, and soil heating is inefficient for heating the greenhouse, and are especially ineffective for plants that don't have very extensive root systems in the first place.

If you'll provide the following info, I'll work up an estimate on the size of heater you'll need:

Total surface area of the greenhouse covering.
What, specifically, will it be covered with?
What are your all-time expected winter lows?
How warm do you want to keep it?

This is the greenhouse I'm getting... Small Greenhouse Kit - 6 Ft. x 8 Ft.

1. The greenhouse has a surface area of roughly 172 cubic feet.

2. It is covered with UV-coated polycarbonate panels. It's completely sealed.

3. It can sometimes get down to around 30F in the winter AT NIGHT and maybe 40F AT NIGHT on average in the winter. In the day it's usually about 50F-70F on the coldest days.

4. Since I am keeping pineapples, I would like to keep it around 60F AT NIGHT. The sunlight should heat it up a bit in the day, probably to like 70F or something.

The heating cable is to keep the soil warm so that the roots can function properly. I am aware that it won't heat the greenhouse air. What other *cheap* methods of heating the air are there?

[katrina]

Pineapples can not take temps as low as you're describing. Ideal lows = 65-75 degrees...definitely not below 60. Even if the soil temps are warmer than your described lows...the tops will suffer cold damage.

The other thing to consider...if there is no sun on a day...the temps will not heat to what you're describing. A cold day + no sun = cold greenhouse if the temps are cold outside.

Sounds like you're going to either need to get a real g/h heater than can maintain the ideal temps...or figure out something that doesn't mind the cold temps you're describing.

BTW - all plants require dark time. It's not necessarily a rest time...rather it's the time when they use the energy the leaves have stored during the day by converting those materials to the necessary components needed for growth and eventual flowering. You might consider it the time they "eat". Leaves store energy from the sun during the day...they use the energy at night. You can google it and read a lot more if you'd like.

[Leafmite]

I have a few planted pineapple tops. In the summer I put them outside and in the winter, I just stick them near any window. Since they don't get great light and the house is cooler, their growth slows and I give them less water. I'm not certain how many you wish to grow, but it might just be easier and cheaper to grow them inside, under lights. Heating a greenhouse is expensive and if the heater fails, all the plants are lost. Many in our orchid society prefer lights to a greenhouse and grow their entire collection under lights. Pineapples are sensitive to cold but they can tolerate short periods of colder weather (as long as it doesn't get below freezing at night and is warm during the day), like any tropical plant. Good luck!
Leafmite

[Leafmite]

Oh, I didn't see that your temps are pretty warm in winter. I live in Ohio so I was thinking snow and ice. I put mine out in the spring when it is above forty at night with most of my other tropical house plants. Hope that helps.
Leafmite

[KenFL]

Hi Dihcro,
In Miami I can grow them outside.

[Dihcro]

I did a pretty good amount of research last night and I talked to some people today. From my research, I found a couple of different ways of naturally heating a greenhouse. I can place some thermal objects, such as black buckets of water/rocks or some naturally insulating ground cover. I also read about how you can cover the greenhouse with aluminized curtains, which can help prevent up to 70% of heat loss during the cold nights. Then my favorite way to heat the greenhouse... Bunnies! Sadly, I don't want to buy rabbits, so that idea is out. I'll be looking around for some aluminized curtains to cover the greenhouse and I'll work on a plan to add thermal objects into the greenhouse.

I mentioned that I talked to some people as well. I went to a hardware store today and was talking to one worker about the greenhouse they had for sale. It was fabric, so not what I wanted, but the dude (who lives pretty close to my house) said every plant in his backyard is tropical, and he hasn't lost a single on yet. He has banana trees, birds or paradise, orchids, pineapples, etc. Anything you can think of that is tropical. All he said he does is put a layer of mulch over the ground and it acts like insulation. He covers the plants when it gets cold outside. That's it. His banana trees bear big fruit and they're perfectly healthy.

I'm going to run the greenhouse without electrical heat. I will use natural heating, such as filling buckets with boiling water and sitting them in the greenhouse on those cold nights, and I can also heat some rocks in my fire pit and put them on the ground inside the greenhouse to warm it up.

The pineapples plants I'm getting are from the tops of $3 grocery store pineapples. It's not like I'm losing $20 every time a plant dies. I can experiment over this winter, I'll see what works and what doesn't. If absolutely necessary, I can invest some sort of electric heating, but until then, I'll test out natural heating.

Originally Posted by Leafmite

Oh, I didn't see that your temps are pretty warm in winter. I live in Ohio so I was thinking snow and ice. I put mine out in the spring when it is above forty at night with most of my other tropical house plants. Hope that helps.
Leafmite

Right now it's in the mid forties at night, it will probably stay around 40 degrees at night throughout winter, with the exception of a few days. I think it was only really cloudy for a week last year, but it was still in the mid fifties for a good part of the day. Most of the cold comes from the wind, and since the pineapples will be inside the greenhouse, they won't be exposed to the wind. The greenhouse will also protect the plants inside from frost, so they're safe in that aspect too. We almost never get snow here, but when we do, it melts before it hits the ground.