Do I need to add supplemental lighting to my new indoor greenhouse?

March 4, 2010 7:58 AM

I've got a 4-shelf indoor greenhouse. Questions about lighting inside.

For Christmas, my wife bought me an indoor greenhouse (pretty much identical to this one). The problem is, that I'm not really sure how best to use it.

I'd like to use it to start as many of my own vegetable plants as possible to be later transferred into the garden. Initially tomato, eggplant, peppers, lettuce/spinach. A little later peas, beans, cucumber, squash, etc. Nothing unusual or exotic.

I'd like to keep it in my office, which is warm (65-72 degrees) and has some indirect window light (but not much) from a northeast facing window.

According to my local gardening guide, the time to start a few of the plant varieties from seeds in March 15. The last frost is generally around May 1. So I've got about 6 weeks to take care of the earlier plants inside this greenhouse, with new plants being started every couple weeks.

Is supplemental lighting a good idea or necessary for this location/setup? If so, do I have to rig up a fluorescent hood for each of the 4 levels in the greenhouse? Is there anything I can use to do that cheaply?

posted by csimpkins to Home & Garden (5 answers total)

Best answer: That's not really an indoor greenhouse -- note that the description says "...fits in the corner of the garden, on the deck, patio or balcony..." Vegetable plants generally require a lot of light. Unless you can find a big, unobstructed south-facing window, you'll need artificial lighting to do a good job of this. Cheapest way to do it is to use four-foot t8 shop lights (less than $10/ea. at Home Depot). No need for fancy grow-light bulbs; cool white will do fine. Artificial lighting is much less intense than sunlight, so hang the lights as close to the developing seedlings as possible. Adjust the height regularly using the chains that the lights hang from

No offense to your wife, but if that unit was intended for starting vegetable seeds indoors in a cold climate, I'd return it. It's just not suited to that purpose.
posted by jon1270 at 8:11 AM on March 4, 2010

Also, peas, beans, cucumbers and squash (especially winter squash) can/should be started directly in the garden rather than indoors.
posted by jon1270 at 8:38 AM on March 4, 2010

Best answer: I'm with you on the peas and beans, but I always start cucumbers and squash indoors.

That setup would be best for hardening seedlings you've already started indoors. Keep the plastic rolled down the first week they're out, roll them up the second week, plant them in the ground the third.
posted by electroboy at 9:54 AM on March 4, 2010

Seeds are cheap or free, so it's worth a shot. Your plants will likely become very leggy as they search for the amount of light they need. I agree that it's best to have a south facing window in your locale, and a grow or shop light placed very close to the soil will help, but early on soil temperature is what gets them started. Through the growing season, those tomatoes and peppers will appreciate heat more than the spinach and lettuce. Don't forget to harden them before transplanting.

You can start the peas and beans indoors but they are very sensitive to transplanting. I start them in an old rain gutter and gently slide them into their places in the garden when the time comes.

Good Luck!
posted by surfgator at 10:06 AM on March 4, 2010

Best answer: Cheap fluorescent shop lights are the best solution. You need one per shelf. Do as jon1270 says: keep the lights as close as possible to the seedlings. I would recommend using a set of shelves that is better suited to your needs. You don't need the plastic around your plants (65-72 is already plenty warm for seedlings and the temperature would get much to high with a bunch of fluorescent bulbs in there) and the dimensions of the shelves on that unit are less than ideal for 4 foot light fixtures. You could potentially use this unit to germinate your seeds (where a higher temperature is useful), but it looks rather large for that.

You will not grow useful seedlings with indirect light from the northeast. Your seedlings will be leggy to the point where they will fall over and die.
posted by ssg at 10:48 AM on March 4, 2010