How To Build an Indoor Seed Starting Setup

Several years ago, provoked by Spring fever and taunted by the sight of seed starting flats and racks of seeds in the local home goods store, I decided that I would grow seeds indoors. I cleared a corner of a little plastic shelving unit by a sunny window in my mud room, watered down the little Jiffy seed starting pellets I’d purchased, added seeds and hoped for the best. A week later I was amazed to see seedlings sprouting. A month later, I was saddened to see that my seedlings had grown tall and droopy and looked weak, despite my best efforts to sustain them. A few tomatoes survived to be planted outside, but they were never very healthy and I don’t think they ever produced blooms, much less fruit.

What had I done wrong?

It’s All About Light

A little research was all it took to help me realize where my seed starting experiment had failed. My sunny window wasn’t enough to get my seedlings to thrive–they needed much more light. The reason that they’d grown tall and spindly was because they were reaching for the distant light shining through the window, desperately trying to generate enough energy to grow. I decided that if I wanted to try starting seeds indoors again (and I did, because what better way is there for a gardener to chase away the late-winter blues than to sprout green things indoors?) I would have to devise a system to generate light and lots of it. I did more research, and came up with a system that has worked well for me now for a couple of seasons and cost far less than the seed starting setups you’ll find in catalogs.

Here’s what I did…

Building the Light Setup

You’ll need a few supplies to get you started:

  • Wire shelving unit at least 36″ wide
  • 4-8 two- or three-bulb shop lights
  • 8-16 S-hooks
  • 6 12″ lengths of light gauge chain
  • 2 2-4′ lengths of light gauge chain (depending on ceiling height)
  • 2 toggle hooks
  • Outlet strip
  • Light timer

Your supply list may vary a bit depending on your setup, but this should give you an indication of what you’ll most likely need. You should be able to easily construct your light setup in a couple of hours.

Step 1
wire shelving unitBuild your shelves so that they are equal distance apart as shown in the photo to the right unless you anticipate growing a number of tall seedlings. (Your tallest babies can go on the top shelf. More on that in a moment.)The first step, of course, is to construct your shelving unit. It helps to have another set of hands as you put this together. One 36″ unit will hold 2 seed starting flats on each shelf (although they will hang over the edge just a bit. I haven’t found this to be a problem.) You can get a wider shelving unit if you like, but I’m all about economy. My unit cost $40 on sale, and they’re not difficult to find at this price after the holidays when items for storage generally go on sale.

Step 2

Once you’ve built your shelving unit, assemble your shop lights and install the bulbs. I purchased the 2-bulb units from Walmart, which cost about $10. The bulbs cost around $8 for a pack of two. Some seed starters will swear that you need 2 shop lights per shelf so that you’re getting the most light coverage. I’m not saying they’re wrong–the more light the better. I will say that, being the frugal (read: cheap) woman that I am, I’ve made do with one light per shelf and my seedlings are none the worse for wear, although I do rotate them every other week so that the seedlings on the outside edges of the light area go to the center and the ones in the center spend some time on the dimmer edges.

Quick tip: Install your bulbs and test your shop lights before you hang them under the shelves. They’re a pain to troubleshoot once you’ve hung them.

Step 3

Using the 12″ lengths of chain and S-hooks (these may be supplied with your shop lights, so check the box before you buy extra) hang the lights from the shelving unit, one to a shelf. An S-hook on each end of the length of chain will make moving the lights up and down as your seedlings grow much easier, so don’t skimp on the S-hooks.

Plug your lights into the outlet strip, and plug the outlet strip into an auto timer. You’re going to want to set the timer to provide about 16-18 hours of daylight. (The timer’s off time should correspond with when it’s fully dark outside.) Some growers leave their lights on 24/7, but I prefer to give the seedlings a break (as nature would.) Although seeds sown indoors need many more hours of artificial daylight than nature would provide in late winter or early spring, I also believe they need some off-time. My thinking isn’t particularly scientific, but it works for me, and it seems to work for my seedlings.

A Note on Bulbs

It isn’t necessary to buy expensive grow lights. In fact, for seed starting, the bluer light that comes from regular fluorescent bulbs seems to work just fine. I buy the bulbs marked “cool” or “daylight.” As your seedlings start to grow, you can rotate in some bulbs marked “warm” or “indoor.” One cool light and one warm light per fixture provides a fuller spectrum of light for young plants and is particularly helpful if you’re trying to give blooming plants a head start. I use it on things like impatiens, petunias, pansies and edibles (such as tomatoes) to good results.

Step 4

You’ve noticed by now that the top shelf of your light setup doesn’t have a light. You can use that for storage if you like, but I prefer to maximize all my available growing space. What to do? Hang a shop light from the ceiling, of course!

Measure your light fixture and decide how you want it to align with the shelving unit. Measure and mark where you’ll place the toggle hooks. Install the toggle hooks and hang the longer lengths of chain from them. Suspend your shop light above the top shelf of your unit. Voila!You’ve got yourself a 4-shelf light setup.

You don’t need an ultra heavy duty shelving unit here, but you don’t want a flimsy one, either. As I mentioned, mine cost just $40 on sale, although they usually retail for around $60.

Goodbye Winter Blahs

seed starting setup

Having green things awake indoors when everything outdoors is still asleep is the sure cure for cabin fever.

Lights and bulbs are not very expensive. Don’t let anyone tell you that you have to spend a fortune on grow lights to get good results. (Do listen if they say that you should replace your bulbs every couple years, even if they’re not burned out. Although your eye can’t see it, older bulbs produce much less light than fresher ones.) I spend about $20 each for four shop lights and bulbs.

All told, my setup cost less than $160. (Compare that to a setup sold commercially and you can see that I saved a ton of money.) I can grow 8 flats of seeds at one time and I can rotate seedlings out as they’re old enough to put in a cold frame or greenhouse outdoors. My setup is, of course, reusable year after year, requires little maintenance (except bulb replacements) and produces tons of seedlings (at least 72 per flat) that I plant, give to friends, and even sell. I consider my light setup a great investment!

I’ll write more on seed starting in a day or two. Meanwhile, I hope you have a great time chasing away the winter blues with a new seed starting setup.

This article originally appeared in Petiole Junction, March 2011. 


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