Winter growing under lights

and the cost per bean ?

 

Cor, this is really getting into the spirit of bean counting, but I'll have a go:

Seeds - zero as they're saved seeds
Pots - zero/negligible as they're re-used and I got them from Wilkos @ 1p for a 10 pack.
Potting compost - 0.45L @ 4p/L = 2p
Water - free as I'm not on a meter so doesn't cost me any extra
Electricity & Equipment - zero as they're occupying space that would otherwise be unused at this time of year.

Total cost = 2p per pot, approx. 20 pods per pot, that's 0.1p per pod If they're picked at 100mm long and weigh say 2.5g each there would be 400 per Kg/40p/Kg. (they are £4.88/Kg in Asda, plus mine will be much fresher being picked minutes before cooking).



Two herbs that have been growing well under lights are Oregano and Curly Parsley (flat leafed has grown spindly)

 

thank you Scrungee. Not sure how they are availing themselves of free electricity but even so, that's an incredible bargain and I know they will taste 100 times better than Asda's Kenyans that have been on a gruelling nightmare journey to get to the checkout,
Jenny
enjoy

 

These Heliopsis have got off to a flying start under my lights which I hope will mean some earlier cut flowers

 

Scrungee, how do you avoid damping off and fungal diseases?


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I get less (in fact virtually nil) mould growth and damping off in the growlight box than in my greenhouse, but my extract ventilation system might help a bit.

 

Hmm, I might have to get a little electric fan. Although with the light and heated propagator it feels like it might become quite expensive electricity wise.


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Based on 7p Econ 7 Night Rate and 25p Day Rate (just to make calcs easy easier)

Propagators: Three x 50 Watt Propagators on 17 hours/day (when lights off)/1000 = 0.05kW x 17 hrs x 30 days x 3 = 76.5 kWh @ £0.07 = £5.35, on between Jan to March, but not every day and not always full power, so say £10.

Lights: Growlight with 8 x 54w tubes, on for say 9 hrs/day for 8 weeks and 18hrs/day (2 'shifts' when more plants) for 4 weeks. 8 x 54/1000 = 0.432 kW x 9hrs x 60 days = 233.28kWh @ £0.11 (av of 7hrs @ 7p and 2 hrs @ 25p) = £25.66. Plus 0.432 kW x 18hrs x 30 days = 233.28kWh @ £0.18 (av of 7hrs @ 7p and 11 hrs @ 25p) = £41.99, Total = £25.66+ £41.99 =£67.65

Fan: 0.24A/12V Computer case fan, reduced in speed by say 50%. Watts = amps x volts, therefore 2.88W x 50% = say 1.5W/1000 = 0.0015kWh, only on when the lights are on (gets a bit warm with 0.432 kW of lighting on), 0.0015 kW x 9hrs x 60 days = 0.81 kWh @ £0.11 = £0.09. Plus 0.0015 kW x 18hrs x 30 days = 0.81 kWh @ £0.18 = £0.12, Total = £0.09+ £0.12 =£0.21

Total Cost of Electricity = £10 + £67.65 + £0.21 = £77.86 for 3 months, or about 90p/day £6/week for getting a head start on hundreds of plants and being able to start gardening at Xmas. Using it to extend the season to get late crops of tomatoes, chillies, peppers, basil, French beans, etc. through Oct to Dec should cost less than £4/week.

Most of the £10 cost of electricity for propagators Jan to March would probably be incurred anyway, just at a later date when the greenhouse heating goes on in March, but the lights might go back on for short periods in April for squashes, so I haven't adjusted further.

 

After being on for 2 months I reckon I've used about £30's worth of electricity using above setup.

I'm not including the £6.40/week [1] cost of my second growbox (8 x 24 Watt tubes running 24/7 with plants being swopped every 12 hours) as that is saving me putting the greenhouse heating on.

I've now got/had over 800 plants (100 leeks helps boost that, pots of herbs counted as 1 unit) in various stages from still germination to 400mm high benefit from lights and propagators, so only an extra over cost of 3.5p per plant/pot so far.



[1] 8 x 24 = 192/1000 = 0.192kW x 24hrs x 7 days = 32kW/hrs @ 20p (av. of 7hrs @ 7p and 17 hrs @ 25p) = £6.40.

 

Hey Scrungee, thanks for all of the info, this is reassuring to know.

Have you ever experienced leaves curling inwards? (underneath the leaf) My coleus is doing that slightly which I though was just how it wanted to grow, but I notice one of my Rudbeckia seedlings is doing that too. I wondered if the light was too close / warm? It's hard to tell, as it's about 4 inches from the top of the leaves but it does feel warm (it's quite new).

 

Curling downwards yes (but not inwards upwards), which often happens with tomatoes and is normally combined with the leaves turning a darkish, bluish green, but a short break from artificial lighting normally gets the leaves returning to normal, although this side affect wont affect something grown for an edible crop to the extent it will spoil the appearance of an ornamental plant.

@JackJJW Could you post some pics? I was going to give Coleus a try under lights myself sometime

 

Ok, thanks I will try moving it into indirect sunlight this week. It seems otherwise healthy. It's the one seedling that survived my tray of damping off'd Solenostemon. I have another small tray doing well in natural light I plan to prick out to individual pots this week and move some of those under lights.

Photo attached - ignore the white splodges, I just sprayed everything with a weak fungicidal spray to further avoid damping off issues. Everything is now growing fine and I don't want any out break to ruin that!


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It's a bit of a trial & error process with growing 'normal' plants under lights as 99 -100% of online advice is for growing illegal stuff.

 

Just out of interest, why do the leaves curl? Is it too much light?


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