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Growing geraniums and marigolds from seed under light

Posted by jollygreegiants none (My Page) on
Thu, Dec 5, 13 at 14:17

Hello! I am trying something new this year. I want to grow two different kind of flowers -geraniums and margiolds- in a tightly packed 8 by 8 foot area in my basement. The basement has very little sun light and so I'm going to need some artificial light to provide 95% of the light for the plants.

The plan is to grow the flowers from seed, then have them indoors as flats for a few months before planting them outside when it's warm enough for them.

The one big thing that is tripping me up is what kind of light to get.

If I'm growing the plants from seed and they will still basically be small-ish flats when I take them outside, how am I supposed to judge how powerful of a lamp I'm going to need and how am I supposed to judge how far to have the plants from the light? Obviously I want to be as energy efficient as possible, but the plants can't be so close that the plants are burned, and it has to be far enough away so that the angle of the light will cover the area that needs to be lit.

It seems like there's about 5 variables here and if you change one, it effects all the others. Can someone please give me a starting point? Should I focus on height above the plants, then adjust the power of the lamp and the hours the lamp is on? Or should I start with the power of the lamp, and then adjust...etc,etc. It all seems very confusing! Would really appreciate some guidace.

Follow-Up Postings:

RE: Growing geraniums and marigolds from seed under light

For seedlings, I find that florescent shop lights work well.

Currently my main light shelf has 1 4' 4 lamp HO T5 fixture, two 4' HO T5 2 lamp fixtures, and two 4' two lamp T12 shop lights that my mom probably bought for $8 or less years ago.

On large plants I've made a stand and amusing CFLs in brooders. I also have started using CFLs for side lighting here and there. I love the clamp on brooders for adding light as needed.

I typically start my seedlings under the shop lights and move them under the HO lights once they outgrow that shelf. I'm pretty sure I had my pansies under the shop lights the whole time last year, and they were blooming and happy when I moved them out last spring.

RE: Growing geraniums and marigolds from seed under light

You need fluorescent lights. 48 inch shop lights are commonly used for these purposes. There are two kinds: One uses T5 bulbs and other T8. The T5 are fatter and use 48w per bulb. T8 s use 32w per bulb. I have two sets of T8 system. Each set costs about $20 (Fixture + bulbs).

I can think that for an 8 ft x 8 ft area you will need 8 sets , if you use the whole area . BUT that sound like a commercial operation. Probably you can get by 4 sets maybe less.

You will have to have a system that can be adjusted, as the seedlings grow. The easiest would be to adjust the lights.

You will have to germinate your seeds first. For that, you do not need light but a warm place . Light is needed after germination. The distance between the top of seedling and the light should be no more than ONE inch. So there comes a need to adjust the lights very often as the seedlings grow.

If I were you, I would start with 2 sets and do experimenting and you will then learn from your own experience and needs.
There are wealth of information on youtube about starting from seeds on videos. It is much simpler that way to understand how to do it. There other other issues are involved beyond lighting, such as seed starting mix, watering, fertilizing, repotting.

RE: Growing geraniums and marigolds from seed under light

Wow, thanks for all the great help to both of you! Are there any specific brands you can recommend for the specifications you guys have provided or are they all sort of a wash?

I have found the bulbs for around $8. Does the brand matter? Should I be aiming for a specific number of lumens or K?

Have not see fixtures for any sort of reasonable price. Maybe I am looking in the wrong places! Would you recommed 2 bulb fixtures? I assume for the price you said you must be.

This post was edited by jollygreegiants on Mon, Dec 9, 13 at 13:26

RE: Growing geraniums and marigolds from seed under light


I assume your 8 ft x 8 ft area is going to be your total working area; not necessarily completely full of plants. Right? How many plants do you intend to grow? No one can give you good advise about lighting without that information. As far as I’m concerned, the space in your basement that you’re using for plant growing has little or no effect on how many, or what kind of, lights you’ll need. What really counts is how many plants you intend to grow under the lights :-)


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