I hope someone answers you because I saw those and was wondering the same thing! Tamara

I believe this is the one also known as the Chroma 50. It used to be one of the favourite fluorescents for dedicated artificial light growers because of its wide spectrum. It is maybe a little past its best now and I certainly wouldn't pay extra for it just for raising seedlings. But if you want to try it then go ahead and let us know how things go.

Plants use light colors for different things. The green range is mostly rejected--that's why plants are green. (Most "grow lights" have a lot of green; that's why they make plants look so good.) The red, or warm, range is used for setting seed and fruit production. The blue range is used for plant growth.

So, if you're just starting seeds, go for the regular old bulbs. I've used warm white bulbs and cool white, and have seen no improvement in seedling growth with the warm white bulbs. It's the cool white light you need, and your seedlings will thank you for it. If you want to put more money into making your seedling growth better, try to find reflectors for your fixtures, or put aluminum foil or mylar up around your setup.

HTH!

Andalee
(An old-time GardenWeb seed starter . . . )

The green range is mostly rejected--that's why plants are green. (Most "grow lights" have a lot of green; that's why they make plants look so good.) The red, or warm, range is used for setting seed and fruit production. The blue range is used for plant growth.

I'm sorry but this is just garbage in so many ways. Plants are green because they reflect some of the green light, but they also use a good proportion of it (roughly 30%-60%) for photosynthesis. Specialist plant lights specifically aim to include only red and blue because these colours are more efficient for photosynthesis, hence fluorescent grow lights look pink or purple, although the lower light levels provided by these types of fluorescent mean that there is not a huge gain to be had from using them. HPS lamps, the favoured lamp of commercial growers, produce most of their light in the yellow wavelengths that are not the most efficient for photosynthesis but the fact that they produce so much light means that they still produce as much or more plant growth than other light sources. There are lights with a lot of green wavelengths promoted as "grow lights", for example some wide spectrum fluorescent lights. They make plants look good because they include a wide range of wavelengths and so render colours accurately, not because they include a lot of green. If just the green was the main reason then plants would look good under green LEDs and trust me they don't!

All wavelengths are used for growth. The blue for growth and red for flowering is a trite myth created by comparing just two types of light, HPS and metal halide, which have very particular spectrums. HPS happens to be "redder" and happens to promote flowering and fruiting, while metal halide happens to be "bluer" and happens to produce more compact growth without flowers. Other "red" lights produce strong compact growth without flowering, while other "blue" lights produce etiolated growth with flowers.

Leaf size and orientation (eg. following the sun) is controlled mainly by some blue wavelengths (the ones that fluorescents produce, but oddly enough not the ones where metal halides have most of their output) but you don't need much, certainly a cool white fluorescent has more than enough blue. Inter-node length (etiolation) is controlled partly by those same blue wavelengths but also by the ratio of red wavelengths to far red (actually into the near infra-red) wavelengths. Light sources with a strong red component but very little far red produce very compact growth, while bluer light sources that include far red light produce etiolated growth. In practice, this ratio is hard to control with commercial light sources (the wavelengths are not strongly visible to humans) and historically the brute force approach has been to pile on loads of blue light to keep the growth compact. Flowering is controlled by a variety of factors, including temperature, day length, night length, and light wavelength. For a few plants that happen to have received a lot of attention, flowering and fruiting is strongly influenced by those same red:far red wavelengths.

Don't put aluminium foil anywhere near your lights, it is useless. Use mylar if you have it, otherwise use white card or anything painted with flat white paint.

OK, so it sounds like there is really nothing to be gained from "sunshine" bulbs as far as starting seeds goes. But here is another question: are two 20 wt bulbs going to be enough light for my babies (which have germinated since yesterday - hurray!)? Admittedly, the space is fairly small, 24" wide by about 18" deep and 15" high - perhaps if I place white around whole area (top, sides, bottom) it would be fine? Also, "shrubs" mentioned white card - are we talking white posterboard, or what about something like white foam board? These are in a mini-greenhouse, so there is a shiny clear plastic cover over the entire structure.

Here is a link that might be useful: Example of My Greenhouse

Isn't it fun when seeds germinate so fast? I have found they really sprout quickly under lights - sometimes too quickly, as they grow too big before it's warm enough to put them outside.

What kind of plants are you sprouting? Your fixtures won't be enough to keep high light, tall plants like tomatoes happy for months.

Hi, watergal! Monday night, I seeded my Summer Carnival Hollyhocks and last night they were up enough that they were able to come out of the incubator and under the lights (though I do have a little light over the incubator also). I am hoping for first year blooms, which is why I started them so very early.

I also started some snapdragons and bunny tails. The bunny tails' package said to start them 10 weeks before setting out. Snaps can take a little cooler weather, so I went ahead and chanced starting them as well. Once things get too big for the indoor greenhouse, I will place them in a cold frame outside to harden off.

I bought two packages of the hollyhocks - I intend to start another set in about 6 weeks to see how they compare with the early set. I'm still pretty new to this, so I am experimenting a little - having fun.

To be started later - I also have some delphinium seeds (which generally don't do well around here, but they are so pretty I just want to try them anyway), some foxgloves, annual stock, larkspur, zinnias, "fancy" marigolds (which I will probably direct sow), hmmm ... I can't remember the rest. The delphs and others like the "chilling" method, so I will probably start them pretty soon.

It's been so mild here so far this winter, I am hoping to be able to plant stuff the first couple of weeks of April or earlier. My roses looked like they were about to leaf out until about a week ago!

A rough rule of thumb for starting annuals under fluorescents is that you can light as many seed trays as fit more or less right under the lights and grow them to a few inches high. You won't be able to stick the fixture a foot above the trays and light twice as many because it won't be bright enough. So, in your case, as many trays as make two feet long :)

Many of your plants will do much better planted in a very cool spot. Foxgloves, Larkspur, Stocks, will all do poorly at typical indoor temperatures. Maybe they'll be OK in an unheated basement or similar. Things like Zinnias and Marigolds will thrive under lights, but grow so fast that they'll be tall enough to harden off after three or four weeks at most.

i conclude from the above that normal flourescent lights are fine for starting provided the light 'lumens' is high enough.
what i also saw was something about 'heat mats' and 'watering mats'. i also would like to know what kind of 'trays' are used to start seeds. i'll look further in the website but does anyone have recommendations for these components?

You're right the amount of light is the most important thing, by far more important than anything else, although it is actually the light intensity, light in a particular area, that is important. Light spread out too much is no good for plants. Light intensity is most easily measured by foot-candles, which are lumens per square foot. Lumens are not the ideal measure of light for growing plants but it is the only one you will find on a very wide range of lighting products so that you can compare, plus you can measure them with commonly available tools such as photographic light meters and even digital cameras. Many sellers of plant lights will tell you that lumens are useless, try to befuddle you with some other measure of light that makes their products look good, but in practice lumens are more or less comparable between most common lighting products.

Cell packs.
Seed trays.

Watering mats are capillary matting that provides water to plants over a long period of time, the modern equivalent of a bit of string in a bucket :) Handy if you are going on vacation. I don't use them, I just sow seeds when I'll be around to water them every few days.

Heat mats can be handy if you need to raise the soil temperature a little. I don't use them, I sow under lights which make things plenty warm enough.

I always had trouble keeping my seedlings evenly moist because the lights dry them out so fast, until I started with the capillary matting. I won't grow them any other way now. I'm into lazy gardening. But I don't start tons of seeds - it could get expensive if you're doing a lot of them.

Yeah, the plant lights sure do keep things warm enough. My grow room now has so many lights that it's really too warm to start most things from seeds any more (but the tropical hibiscus shrubs and waterlilies are lovin' life!)