06 March 2009

Starting Seedlings Indoors: Its all about light

It has been warm here (almost 60 degrees today!), the days are getting longer, and the air smells like, well, like SPRING IS COMING! Which means I'm full of pent up gardening energy even though it is far too early to actually be out working in the garden. Thank goodness I have all those seeds I ordered to sow. Otherwise I'd probably start browsing catalogs again and find more plants I can't live without and can't afford.

So I've been starting seeds. Growing your own seedlings for the garden isn't hard, but there is one key feature that a lot of people get wrong: Light. Seedlings need light -- LOTS of it. Too little light causes seedlings to grow long, spindly, and weak – light is what they use to make food, remember. Anorexic seedlings will limp along and the completely collapse when you plant them out into the garden. If you just focus on giving them lots of light, most of the difficulties of seed starting vanish.

There are three simple ways I've used to successfully to give seedlings enough light and let me say now that none of them involve a window sill – even your sunniest windows doesn't have close to enough light – and none of them involve those "light garden" setups you see in garden supply catalogs. The ones I've seen always have too little light, and are way over priced. So here is what does work:

Desk lamps with compact florescent bulbs:
This is a great, low cost way if you are just starting a few tomatoes or flowers. The secret is to use the brightest bulbs you can and keep the bulbs as close to the plants as possible. Aim to keep the lights on 16 hours a day -- either turn them on and off when you get up and go to bed, or (if you are forgetful like me) get an inexpensive timer to plug them into. Be sure to use compact florescent bulbs -- traditional incandescent bulbs waste energy, get too hot, and produce a lot of a kind of light we can't see called far red, which causes plants to stretch and get spindly rather than stay nice and compact.

Shop lights with florescent bulbs:
This is a step up from the desk lamps, and will allow you to start enough seedlings for a reasonable size gardens. Just be sure not to skimp on the light: for healthy seedlings, you want a minimum of four bulbs right next to each other – the cheapest and easiest way to get that is buy two standards shoplights with 2 bulbs each and hang them right next to each other. Then lower those lights so they almost touch the seedlings so they get as much list as possible. And just buy regular florescent bulbs, not those expensive "plant light" bulbs. Those bulbs are designed to emit light which will make your plants LOOK prettier, but they'll grow just as well under the cheaper, regular florescent bulbs.

High Intensity Discharge Lamps (HID lamps):
These are lights for serious seed starting -- or even for growing tropical plants year round like a mini greenhouse. They will set you back a few hundred dollars or so, but these lights actually produce amounts of light close to sunlight and will grow a lot of beautiful, compact, healthy seedling. Your neighbors may assume you are growing something illegal with it, but they'll change their tune when they see the lovely heirloom tomatoes you get to feast on all summer.

But how much will it cost you to run all these lights? Less than you might think, and the exact amount is easy to calculate for the purposes of convincing skeptical spouses and partners. Your electric bill will have the amount they charge you per "kilowatt hour" -- 1 kilowatt hour is simply 1000 watts of electricity used in one hour. So, to calculate the cost to run your lights simply add up the wattage of the bulbs (for a four bulb, two shop light set up, about 160 watts) divide by 1000 (0.16) multiply by the 16 hours a day it will be on (0.16 x 16 = 2.56) and multiply that by what your electric company charges you per kilowatt hour. My company charges about 8 cents, so those lights would cost me about 20 cents a day to run. Even my 1000 watt high intensity discharge light only costs me about a $1.30 a day -- you can't even buy a cup of coffee for that, and you'll save a LOT more than that by not having to buy seedlings at the nursery.

So invest in some lights, and get some tomatoes growing!


For anything except the High Intesity Discharge lights, your best source will be your local home improvement store or hardware store. If you want to bring out the big guns, I recommend Home Harvest. They have tons of lights, and a lot of good information as well.


keewee said...

Brilliant idea on using desk lamps and florescent bulbs. I think I will hit the thrift store today, and see what I can find. I like the idea of the timer too, good for forgetful people like myself. My two trays of seeds are sitting on the kitchen table so I would like to reclaim it back.

Greensparrow said...

Thanks Keewee -- the desk lamp idea came about as I was trying to help my sister figure out how to start a few healthy seedlings in a VERY tiny apartment. It works great!

Kerri said...

Thanks for this very enlightening post. My hubby has been making a light fixture for my seed starting (not our first..just an extra one) and we were planning to buy grow lights for the shoplights. On your advise, we'll now buy regulars and save quite a bit of money.
We'll move them closer to the plants as well.
Thanks for the good advise.
I had a chuckle about you planning your vacation around the coveted plant 4.5 hrs away :)
Spring is in the air!! Isn't it grand? :)

Kim and Victoria said...

Great post! We've been planting our seedlings under shop lights for years now and they grow great; still nice to hear it endorsed by an "expert".