I have a small collection of cacti that I have protected from the weather by a clear polycarbonate roofing sheet for the last ten years or so. Where I live (Brisbane, Australia), it is quite warm but rain is frequent in summer.
I have had a few of these plants for 30 years or so and have not always been as dilligent as I should be with repotting. For a long time, I wasn't getting many flowers. Then, a few years back, I made two changes - reasonably regular fertilizing with a low nithrogen fertilizer at half strength and taking off the polycarbonate sheet as much as possible. Flowering increased enormously.
When I bought it, the polycarbonate was advetised as cutting out 98% of UV rays. My question - was it the addition of fertilizer or the re-intoduction of UV exposure that increased the flowering? Or maybe a combination of both? Are polycarbonate roofing sheets OK as protection from excessive rain?
Cheers,
BB
Polycarbonate shelter and flowering
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templegatejohn
- Posts: 1198
- Joined: Wed Sep 01, 2004 2:57 pm
- Location: Leeds, England
Hi there,
It is almost certainly a combination of both. It takes a tremendous effort on the part of the plant to produce flowers and this is certainly assisted by the introduction of fertiliser (I notice you said at about half strength, so you know the correct proportions). Every other watering is a good average for using the fertiliser.
The polycarbonate sheeting will not let anything like as much sunlight through to the plants as the horticultural glass used in greenhouses would do. Sunlight is essential for photosynthesis to take place, so it would seem that the sheeting is allowing the plants to "tick over" rather than growing well and flowering.
You have a bit of a dilemma, do you leave the sheeting on and get poor growth and flowering. or leave it off and the plants open to the elements. They would not like to be left in soggy or water-logged plant pots.
If the protection i.e. sheeting was made temporary and left off as much as possible and only placed over the plants when the weather is bad that would seem to be the solution. Replacing the polycarbonate with horticultural glass would be the best method of all, but may not be practical for you, I don't know.
John
It is almost certainly a combination of both. It takes a tremendous effort on the part of the plant to produce flowers and this is certainly assisted by the introduction of fertiliser (I notice you said at about half strength, so you know the correct proportions). Every other watering is a good average for using the fertiliser.
The polycarbonate sheeting will not let anything like as much sunlight through to the plants as the horticultural glass used in greenhouses would do. Sunlight is essential for photosynthesis to take place, so it would seem that the sheeting is allowing the plants to "tick over" rather than growing well and flowering.
You have a bit of a dilemma, do you leave the sheeting on and get poor growth and flowering. or leave it off and the plants open to the elements. They would not like to be left in soggy or water-logged plant pots.
If the protection i.e. sheeting was made temporary and left off as much as possible and only placed over the plants when the weather is bad that would seem to be the solution. Replacing the polycarbonate with horticultural glass would be the best method of all, but may not be practical for you, I don't know.
John
Last edited by templegatejohn on Fri Sep 30, 2005 7:43 am, edited 1 time in total.
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Turtleman
I use clear polycarbonate siding and endwalls on our greenhouses but we still have to add shade cloth over it in the summers to block the UV from the interior, according to the Mang. specs it only blocks up to 2% of UV the GE clear polycarbonate claims to block none!
Polycarbonate siding is growing fast as the best covering for commercial greenhouses there is
Polycarbonate siding is growing fast as the best covering for commercial greenhouses there is
Thanks for the information, friends. I would have liked to see all of your reply, Turtleman - I am not sure if you were interupted or your whole reply is just not displaying for me.
I think that the particular type of polycarbonate I used was obviously meant to protect human skin - not necessarily allow plants to flourish! It is clear to the eyes and obviously lets nearly all visible light through - but it did claim to cut out almost all UV.
Is there a special kind of polycarbonate specifically intended for greenhouse use?
Cheers,
BB
I think that the particular type of polycarbonate I used was obviously meant to protect human skin - not necessarily allow plants to flourish! It is clear to the eyes and obviously lets nearly all visible light through - but it did claim to cut out almost all UV.
Is there a special kind of polycarbonate specifically intended for greenhouse use?
Cheers,
BB
BB, I don't think Turtleman's post was cut short. He ended the sentance with the linking verb "is" and left off the period. That is why it seems like there is more to the post. The last sentance could be rephrased:
"Polycarbonate siding is growing fast as the best covering for commercial greenhouses available."
or better:
"The belief that polycarbonate siding is the best commercial greenhouse covering is growing fast."
"Polycarbonate siding is growing fast as the best covering for commercial greenhouses available."
or better:
"The belief that polycarbonate siding is the best commercial greenhouse covering is growing fast."
All Cacti are succulents, but not all succulents are Cacti
