Overwintering borderline hardy perennials - Dierama, Arthropodium etc.

[arisaema]

I'm unfortunately still lacking a greenhouse, and have a bunch of seed pots that likely need to stay inside a cold basement over winter... These evergreen/semi-evergreen genera are a bit of a challenge - do they need light through winter, or will they survive kept dark and barely moist?

[Vinny 123]

Coolest, south-facing windowsill, kept all but dry?
Spare bedroom which only has the barest minimum heating?

No light is likely to create a lot of hassle. Providing enough artificial light would be a hasle and not cheap.

[Véronique Macrelle]

and install a frame until we have a greenhouse? a few breeze blocks and one or 2 layers of plastic?
Dierama is hardy enough for here in zone 7 in the open ground. arthropodium, I couldn't keep it indoors because it was too hot, and it froze in the greenhouse.

Deciduous plants go in the garage (frost-free).
I try to keep evergreen plants in an unheated attic, just below the velux window.

[arisaema]

Thank you both, I feared they would demand light... Will likely have some LEDs running in the basement, so the Arthropodium candidum 'Rubrum' can go there. The Dierama... Unheated wintergarden will have to do, the main issue there is that it tends to get hot in daytime, and I was hoping to avoid splitting them until spring. They're considered too tender for Denmark, but I refuse to believe it until I've tried!

[Vinny 123]

To provide sufficient light with no daylight, would cost a lot of money.

The human eye - most eyes out there - are amazing biological engineering. Most people can read, though not comfortably, with 10 lux illumination, in the UK, midday sunlight on an overcast day will provide around 5-10,000 lux or a lot less if really cloudy, a clear midday sky in summer will provide over 100,000 lux.
Does your eye allow you to appreciate the >x10,00 difference? Or the >>10x difference overcast to bright sunlight?
Horticultural LED lighting , purposely designed with highy directional beams, to produce growth, rather than just survival, runs at 5-600W per square metre. (As efficient as they are, that energy ends up as heat, very little is absorbed by the plants. That is basic physics, not really biology/botany.)

Even sgnificantly supplementing poor/dim natural light is costly, in both senses - to buy and run.

That said, what are you looking to over-winter? 2 pots? 20 pots? A single golfball low watt LED in a good reflector, can provide 1500-2000 lux 20-30cm below, but you'd need one for each pot unless the pots were very small.

Curious?
Available online for download - Southern African Bulb Group, Newsletter 50.

[arisaema]

I'm using LED grow lights from Temu of all places, ~£14 per piece, 45W. They're certainly nothing fancy, but I used them last winter, and they do seem to work much better than the old HPS and fluorescent tubes. There's a window, but it's facing out under the balcony, so barely gets any light in winter. The rest of the basement is far too warm, with the shed and garage too cold in the coldest part of winter.

That said, what are you looking to over-winter? 2 pots? 20 pots?

Too many, especially once imports arrive and seeds have been sown... I had a slim hope both species would tolerate dark if they stayed around freezing, it's my first year growing either.

[Vinny 123]

They are a con.

Take a look on Philips' website about horticultural lighting. There is far more information there than anyone could ever need, unless your income/business depended on it.
They also compare to HPS and  fluorescent for plant culture. (HPS emits almost entirely in the yellow-orange with minute amounts of other colours, with a tiny blip (increase) in the blue from the mercury).

In total darkness, 45W would need to be tightly focused over something like 30 x 30 cm. If it is rated at 45W, somewhere around 10-15W will be lost in the running gear, so the LEDs will be running at around 30-35W. You can get the same from LED lamps costing a very, very few ££.

Say that you get 100 lumens per watt and there is 35W of LED (which is unlikely as blue saps power (high energy per photon) and lower lumens per watt, and worse), you will have 3500 lumens. Miraculously tightly and evenly concentrated over one square metre that is 3500 lux - very, very dim sunlight.

The multi-colours just add to the gimmick. Although the appearance of the plants may be something like "normal" by eye, the plants just need a little bit of blue and all the rest in red-orange-yellow. Photosynthesis is stimulated most around the orange, blue controls inter-nodal distance, and you don't need much.

Even worse with panels, especially large ones, you cannot replace anything that dies (LEDs, not the plants). Cheap ones even worse again, as they have short lives.

Philips sell one lighting package for a 4 foot cube growing chamber - it just shouts cannabis to me - 650W.
"Standard" single strips of round 1m for plant growth are 100W (actual LED power).

[arisaema]

They are a con.

Yet they work fine, the proof is in the pudding! I have already used them for a season, and nothing got etiolated, both perennial seedlings kept in the cold room and chili peppers in a warmer room...  I used to run a 650W HPS light years ago, hot and noisy and horribly yellow, along with tons of fluorescent tubes - and honestly, the plants I grew under those lights were worse off than what I raised using dirt cheap Temu-LEDs.

At £14... If they die after a couple of years they would still be cheaper than every other option.

[Vinny 123]

4-5 standard LED lamps would cost quite a bit less and do the same.

As I said, they are a con which they get away with because of how eyes work.
You'd need a cheap meter to realise/discover what a con they are.

And the power of the SON and the fluorescents compared to the LEDs? Hardly surprising that they run hot in comparison!! As for noisy? There was something very wrong somewhere.

(Etiolation is abnormally long internodal distance - controlled by blue light - even weak winter sunlight has enough to stop that)

[arisaema]

Your math still doesn't make sense... A pendant with cable and plug is some £8, a Philips 17,5W LED light bulb at the local supermarket is £5.50. To reach the same light strenght of one Temu-LED I'd need at least 2, for a total of £27. Why would paying double be better?

[Vinny 123]

Maybe you do not have to buy the most expensive, perhaps? Lamp and fitting, not the chepeast - around £2 or a little over, each, total, that's what I did.

I would also buy more so that you get a better spread - I use 7W, but you can get lower. Also, the pendants are for ever.

For £14 you could buy a set-up that should last longer and if and when any lamp dies, you could replace it.

The major thing is that you are subject to an optical illusion (actually, the operation of your irises - of your eye, not your garden    ).
I experimented last winter, with 7W lamps 20-30cm above the plants, using reflectors, and I bought a cheap meter (identical to one that a friend had also bought and I compared them - pretty much identical readings, that also made sense). Despite what my eyes told me, the shadow of the reflector reduced sunlight by more than the 7W lamp added - the plants received less light in the lamp beam but in the shadow from the sun.

You will be amazed how much extra light you will get by cleaning the window (although you will not be able to see it- irises again).
Philips give a figure of 30% loss of sunlight inside a clean commercial glasshouse. Ever realised that when you walked into one? Do your eye tell you that? (Mine certainly do not, and never have.)
Mine had a very, very thin film of algae last year - not so very obvious unless you really inspected the glass closely - the light level inside was cut by 50%. (No, not even the 50% drop was obvious to my eyes. The loss of light is down to the glass, but mostly the framework etc.- brand new glass, from memory, absorbs around 10% of sunlight. I also suspect that the milky haze that you can see on very clean but old glass absorbs and/or reflects quite a bit of light, but I never thought to measure that when I hadsome removed from my 30+ year-old greenhouse (my second is far older))
I gave the glass a very, very good clean and the loss was 30% - the plants received 40% more sunlight.

I actually use LEDs over the plants to extend photo-period, not to promote growth. Photo-periodic effects are achieved at very low lux - not much more than twilight.

It is all there on Philips' website

[Véronique Macrelle]

Is it a Dahlia merckii in flower?

I've also installed a small light for out-of-season plants: I don't like it, but I don't really have a choice.

-An Arisaema seedling appeared in a plant I repotted 1 month ago! an old seed that benefited from the reworking of the soil.

-my test sowing of Codonopsis bomiensis seeds germinated better than I expected: 5 plants for 10 seeds tested (the seeds are 9 years old!). as they are precious to me, I had to make them grow... 3 to 4 cm taller since sowing in 3 months.
the rest will be sown in the right season.
i bought a small light bar from ikea (mini greenhouse section, i can't remember the price). compared with your installation, the light is closer to the plants: i put it on the roof of the mini greenhouse, 20/30 cm from the plants.

[Vinny 123]

This has increased in price since I bought mine, but probably cheaper (and certainly a lot more expensive) elsewhere -

https://www.amazon.co.uk/gp/product/B07QFXSDKL/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1