Growing seeds without a greenhouse or "heated" propagator?

You might also consider growing plants to suit your facilities.
Aconitum, Hellebore and hardy Iris seed can be sown in the autumn, placed in the plastic greenhouse and then forgot about. Needing a cool/cold period before germination nature will do it all for you.
Many Tricyrtis also need a period of cool stratification. Sow late winter early spring and place in your greenhouse.
Cerinthe major can be sown in situ in the autumn. Mark the spot so that you don't forget.
There are many, many more that you may consider as above too.

 

Can you get some spare "trays" that fit it?

I sow in batches every fortnight. By the time that 14 days is up most stuff has germinated and can then come off the heat, but it won't be pricked out for, probably, another 14 days. So with two sets of seed trays I can run a production line and only need half of them, actually probably a bit less, on the propagator.

 

I am pretty sure that pete will know this, so just for the benefit of others considering this:

I used to use kitchen foil, just as Pete describes, but I have since read that it isn't a very good reflector of light. Assuming something posh, and highly reflective, like Mylar is not available / affordable then either Polystyrene sheet, or even matt white paint, is more reflective than kitchen foil. Exactly the same principle as Pete describes though

 

Kristen - I remember you saying that before about aluminium foil - and I didn't understand it at the time.

I would suggest that the shiney side of aluminium foil is very reflective. Mylar is simply aluminium coated onto a polyester film, so I can't see that Mylar can be any more reflective than aluminium foil.


I found this at this site http://www.kruschwitz.com/HR's.htm , who sell aluminium coatings for mirrors for telescopes etc.

Visible light covers the range of 400 to 700 nanometers (nm). In another area they quote the visible light reflectivity of Aluminium at 92% and the infra red (ie heat) at 98%. I gather the dull side is closer to 80%.

I have seen aluminium foil reflectivity quoted in some places at around 60%. But I think those guys have been smoking too much of their wacky backy

 

You may well be right, because that is where I have seen it quote. These things get passed around, like Chinese Whispers, so its quite possible that some duff info then becomes accidental fact

I'll see if I can find a link to what I original read

 

I'd be pleased to discover that kitchen foil is a good reflector as I used it for years on my windowsills (on the room side of the plants) to provide reflected all-round light for the plants. It would be good to discover that I hadn't been using a rubbish reflector! but I have read in lots of places that it wasn't as good as either flat-paint or polystyrene (let alone Mylar) so I switched.

I had a Google ...

This is probably a worthwhile read. It is a lone voice suggesting that Kitchen Foil is a good reflector, and everyone else shooting him down.
http://www.rollitup.org/grow-room-design-setup/168489-reflective-material.html
Same bloke getting shot down again:
http://www.rollitup.org/indoor-growing/177656-mylar-foylon-vs-aluminum-foil.html
(Both links are to a Cannabis forum)
The argument seems to be that seasoned growers don't find kitchen-foil effective, and are quoting 50% reflectivity figures but with no links to scientific [peer reviewed] science. Maybe they copied them from someone else, who copied them ... as I did :(

There is quite a bit of talk that once crinkled it is ineffective (angle of incidence becomes sub-ideal); that makes sense but is avoidable by sticking the foil to some backing (bit of a faff, and maybe white-paint is easier at that point). And also chatter that Kitchen Foil is a better reflector of heat than it is light. I couldn't get my head around that. Sure it is usually used for covering the Chicken in the oven, for its thermal properties, but Mylar is in effect a thin metal (Aluminium??) coating over a polymer (ditto a mirror coating in a telescope - we all probably did that mirroring experiment heating foil in a vacuum in physics at school ...) ... so why would the Aluminium not work as well if used as a foil? Mylar would keep the coating "taught", unlike a sheet of kitchen foil, but that apart I didn't see any science that explains why pristine foil would reflect light less well than a couple of atoms' thickness applied to some other material.

As kitchen foil is a good reflector of heat I can see that being a problem with HID lamps (even saw it stated as a Fire Hazard in associate with HID Lamps ... dunno if that is a reasonable assumption though) - if it is crinkled and reflects the heat onto a spot causing a hot-spot, but that's going to need something carefully shaped into a lens isn't it? Seemed to be anecdotal evidence that it does occur though (but I'd be a lot happier with peer-reviewed science and academic citations ...)

So ... dunno! Maybe Mylar, Flat Paint or Polystyrene is a safer bet in case kitchen foil is actually no good for some reason, but I didn't, yet, find the evidence.

Thanks for raising it, would be good to find some proper proof, rather than hearsay.

 

I used plastic mirrors behind my plants for years . Then read on here that mirrors aren't very light reflective I used space blanket material around my bijou light box last year , which seemed OK . Scrungee located some reflective mylar backed material as recommended by our ganja growing chums Who was the supplier of this ?

 

"Thanks for raising it, would be good to find some proper proof, rather than hearsay."

Geoff Hamilton, said so.
You cant want more proof than that.

 

With fresh manure under the boards the heat generated was enough to germinate seeds.


Then cover them over with the frame tops and keep them snug as a bug.

 

I had a look at Wikipedia - who quoted aluminium foil as having a reflectivity of 88% for bright foil and 80% for dull embossed. Probably a more reliable source.

But, having a light meter I thought I would do a test. In a darkened room I shone a light onto the white plastic of the open door of my lightbox, and then did the same after covering it in aluminium foil. It was a very imprecise experiment, as the white plastic scattered the light in all directions, but the aluminium tended to reflect it back at one angle. So I had to move the light meter around over a wide area to try and get an average. The resut seemed to be that the aluminium was at least as good and possibly a lot better than my white plastic covered hardboard - though this isn't quite the same as white paint.

However my original reaction to the suggestion that aluminium foil was not a good reflector was purely theoretical. If I may put my nerd hat on for a minute . Aluminium is a metal and a the major property of metals is that they have loads of loose electrons. Loose electrons do two things - they conduct electricity and they reflect light. So generally the better the electrical conductor the more it will reflect light. This is why transparent things are always insulators and conductors are always opaque and shiney. Aluminium is a very good conductor.

 

One of the points made in the Rant post I linked to earlier was along the lines of:


Take a long-ish, but narrow, strip of foil and dangle it in the flame of a candle.

Your finger won't get hot.

If you took a block of metal, rather than a foil, you'd know all about it.


I didn't try the experiment (and maybe my finger would have burnt?) but if it is right I can't get my head around whether that tells me that Foil is not the same as an ingot of the stuff wrt to both conducting heat AND reflecting light (which was the point the Ranter was attempting to make).

Anyone learned enough to comment?

 

Kristen I can see where you are coming from. There are two seperate effects at work here. The property of the material and the effect of size.

Aluminium is a chemical element that has certain material properties such as electrical and heat conduction and light reflection. These come from the atomic structure and can't be changed.

Then there is size. Water will always flow more easily than golden syrup through a pipe. But if the pipe is thin enough even water will have difficulty in flowing. This is due to the effect of size on the total flow level. But the water will always do better than syrup under the same conditions.

The fact that less heat flows along a thin piece of foil compared to a block of metal is simply a function of size and not the material itself.

In the case of light reflection, size is essentially irrelavent. All the action occurs within about the first ten thousanth of an inch when light enters a piece of aluminum, as aluminium is very opaque to light. A small amount, about 10%, will be absorbed and the remaining 90% will be reflected back from the surface.

But you are right. If the aluminium foil was thin enough, some light would actually pass through it and less would be reflected at the surface. Indeed, some Melinar film has a coating that is only a few atoms thick and as a result is slightly transparent. In that case it would reflect slightly less light. But aluminium foil itself is perhaps ten thousand times thicker.

 

Well ... could be that you've uncovered an urban myth that has been doing the rounds.

The seasoned Cannabis growers say they have had poorer results (and some side effects from hot-spots) from kitchen foil. I'm inclined to take them at their word (they are looking for minuscule improvements in their growing technique, given the high value of their crop), in terms of choosing the best material, although I would prefer a scientific (measured, side-by-side test) to their wet-finger-in-the-air stuff.

But it has always seemed daft to me that something as shiny as a mirror was deemed to be a lousy reflector of light.

 

There could be something in hot spots.

A matt surface will reflect less in total, but will scatter light reasonably evenly in all directions. Even a shiney white painted surface is relatively matt when compared with a mirror. In the case of a mirror, you will have the highest amount reflected in total, but it will all be reflected back in one direction. This means that some parts of the plant could get much more than others.

I don't think too much light would be a problem. Plants saturate if they get too much light and just don't use the extra. But I suspect that it is the concentrated reflection of heat that could fry parts of the plant - they don't like it up'em . This could be a problem with metal halide lights where the source is concentrated. But wouldn't be a problem with fluorescent tubes where the source is very spread out.

It was -7C here last night - so I am currently looking for a hot spot.

Edit : I suspect any problem with local hot spots would be associated with intense cultivation of plants and lots of lights and heat. I wouldn't have thought you would suffer this with just one or two lamps.

 

Water?

Actually, water molecules have spare electrons too, and good job too, otherwise there'd be no such thing as surface tension, no osmosis, and then we'd be in trouble.