I’ve got some flower seedlings growing in a little greenhouse in our living room for spring planting coming up. I was just wondering if leaving the regular 60 watt light bulb on at night would help them out at all. Where they are positioned now, they get the sun from about 7am-1pm. At night, we keep the room in low-light since it’s on the way to the bathroom.
Would nudging up the dimmer switch a little help the plants? Or would I need those high-intensity grow lights they sell at gardening centers to really make a difference?
Incandescent lamps put out too much red, and not enough blue for happy plant growth. OTOH, ‘daylight’ type compact fluorescents work swimmingly on both photosystems: light and plants.
Plants also like to have some night at the end of each day, so don’t leave your lamp on all the time, only enough to boost daylength from the anemic 10:40 of late february, to the high growth 12+ hours that occurs naturally between the spring equinox and the summer solstice.
Note that even aside from the spectrum, sunlight is a heck of a lot brighter than what humans consider a “well-lit room”. This is why grow-lamps consume so much power.
It also depends upon the plant, but for the most part, no. The plants that tend to do well as houseplants tend to be understory jungle plants: plants from a tropical jungle with few variations in temperature, and with very little light penetrating to the jungle floor through the canopy.
There are exceptions, of course, but very, very few plants work equally well inside and out, in most climates.
Certainly, for example, what most people think of as standard garden plants–tomatoes, petunias, marigolds, roses, just to name a random few, will not work inside without artificial support.
Yeah, if you get an incandescent light close enough to the plants for them to benefit from the light, the heat will fry them.
Your seedlings are going to outgrow that “greenhouse” pretty darned fast. You don’t need high-intensity grow lights. Regular old fluorescents will do the job – but they have to be no more than an inch or two above the plants. A set-up where you can raise the lights as the plants get taller is ideal.