Seed Starting Rack




For several years now we’ve tried to start most of our own vegetables (and lately flowers) for our garden from seed. In the past we’ve used a plastic folding table and while it worked, it also took up a lot of space and wasn’t the most attractive thing to look at. So I thought that I would build a rack large enough to hold all of our seed trays, heating mats, and grow lights.

Step 1: Cutting MDF Shelves

I started by cutting the shelves and top from a 1/2” sheet of MDF. In order to fit our four seed trays on a single shelf along with our 4’ lights, I made the shelves 24” deep by 47” wide. I left the top 49” wide (MDF sheets are actually 49” x 97”) so that it would extend a little over the tops of the legs, though to make it even easier the shelves and top could all be left the same size.

Step 2: Cutting Shelf Frames and Legs

For the shelf frames and the legs, I decided to use pre-surfaced pine boards from Lowe's to avoid having to use the jointer or planer. To ensure that the matching parts were identical lengths, I used a stop block for the frame pieces and for the legs I cut them to rough size first and then made a final cut through both pieces at the same time.

To save a little money I did buy 1x8 boards and rip them to size at the table saw, but if you don’t have a table saw you could simply buy 1x3 boards. Once all the parts were cut, it was time to assemble the frames.

Step 3: Assembling Shelf Frames

I kept the frame assembly simple and used pocket-hole screws to attach the short rails to the long rails while making sure everything remained as square as possible.

After finishing the frames I clamped down each piece of MDF to its frame and sanded the edges of the MDF flush.

Step 4: Beveling the Shelves

To protect the front edge of the MDF shelves and top, I decided to cut a small 45° bevel along the front edge at the table saw.

Step 5: Preparing to Paint

It was then almost time to paint, but I first cut several small blocks from an old 2x4 to raise the MDF pieces off the floor.

Step 6: Priming and Painting

To prevent any bleed-through of grain and knots on the pine parts, I decided to use a shellac-based primer for everything. It’s pretty runny, but applying two coats with a 4” foam roller was fast because of its quick drying time.

After a quick sanding and wiping, I applied two coats of latex paint to both sides of the shelves and top as well as the frames and legs.

Step 7: Assembly Hardware

To make it easier to assemble and disassemble the rack if need be, I decided to use 1/4" bolts, washers, and nylon lock nuts. Note that round-headed bolts would work fine and would avoid needing a counter-sink bit -- my store just did not have enough in stock. I also purchased some small right-angle brackets to attach the MDF shelves to the frames.

Step 8: Drilling for Assembly

I marked off where the holes on the legs should go and then drilled the holes at the drill press table. I then drilled counter-sunk holes in the legs.

After marking off where the holes in the frame needed to go, I drilled those by hand.

Step 9: Attaching Shelf Brackets

Before moving everything into the house for assembly, I attached four right-angle brackets to the tops of all the frames.

Step 10: Attaching the Shelves to the Frames

To attach the shelf tops I laid them face down and then aligned the frame so that the rear and side edges were flush. Then I made a small mark for the screw locations using a Philips head screwdriver and moved the frames back out of the way.

I carefully pre-drilled small holes for the screws using a piece of tape on the drill bit as a depth guide. Then it was just a matter of moving the frame back into position and using some small screws to hold it in place.

Step 11: Attaching the Legs to the Shelves

To attach the legs to the frames, I started at the top and just used a screwdriver and socket wrench to secure it to the leg with a bolt, washer, and lock nut.

I then just worked my way down to the middle and bottom shelves and then attached the front left leg before finishing up with the right legs.

Step 12: Completed Assembly

And with that, it was finally finished and ready for some lights and some seeds.

Step 13: Heating Mats and Thermostat

To help with seed germination we use a pair of 20” x 20” heating mats that are controlled by a digital thermostat which makes it great for starting seeds early in a cooler room.

Step 14: Lighting and Seed Trays

For lights, we’ve been using a pair of T8 fluorescent shop lights with a timer, but we’ll probably switch to brighter T5s next year.

We also like using the heavier duty seed trays as they don't bend when weighted down with dirt and plants.

Step 15: Seedlings

After 5 or 6 days on the heating mats, most of the seeds other than our peppers had germinated and it was time to remove the covers.

Step 16: Completed Seed Growing Rack

Hopefully they’ll continue to do well and in a few weeks we'll be able to transplant them into the garden. If you’re into gardening leave a comment below and let us know what types of things you’re growing this year!

Step 17: Rack Materials and Hardware

  • (1) - 1/2” x 4’ x 8’ MDF
  • (3) - 1” x 8” x 8’ Pine Boards
  • (48) - 1-1/4” Pocket Hole Screws
  • (12) - 1/4-20 x 2” Oval Phillips Machine Bolts
  • (12) - #12 Flat Washers
  • (12) - 1/4-20 Nylon Insert Lock Nuts
  • (12) - Right Angle Brackets
  • Zinsser Bin Shellac-Based Primer

Step 18: Seed Growing Materials

Step 19: Tools Used

Step 20: Plans

PDF and SketchUp plans for this project can be found at our website.

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    10 Discussions


    2 years ago

    Hi guys this is a great idea and voted for in garden and woodwork. One little question is about the choice of fluorescent as a grow light - does it have sufficient spectrum of light for growth or is it just a bright source for initial germination?

    5 replies
    gumbytig Oncer

    Reply 2 years ago

    The 3 options I've found in reference to seed starting with fluorescents:

    1 grow bulb and 1 standard bulb

    1 warm white and 1 cool white bulb

    2 bulbs of any type

    All these bulbs I've found at the local big box hardware store. some of it depends on how long your keeping your seeds under lights. If your just starting them and letting them get a few inches tall, most likely any combination from above will do. If your keeping them under lights for longer, you want something more full spectrum and probably more total light per plant.

    AroundHome Oncer

    Reply 2 years ago

    I think we recently ended up with 2 warm bulbs and 2 cooler temperature bulbs in ours though not intentional. Many vegetables will germinate with just the heating mats providing the correct soil temperature. If you notice some leggy tomatoes in the photo above, it's because the tomatoes germinated faster than I could get the lights setup :). Though in the past we've always just setup the lights right after planting the seed.

    AroundHome Oncer

    Reply 2 years ago

    Thanks! We've been using the lights in the article for about 7 years without any issues for vegetables. We do rotate/shuffle the trays around a bit as the seedlings on the edges will lean in a little. I use T5's in our shop and they are *considerably* brighter than the T8's they replaced, so I think we're going to replace these with the T5 fixture I mentioned above as well.


    Reply 2 years ago

    Thanks for that. I was thinking of adverts I'd seen for LED systems sold for growing garden herbs on the counter top in the kitchen but I suppose for germination just a good bright light works as Gumby said. Thank you!


    2 years ago

    Very well designed project and excellent instructable. The instructions were clear and the photos were helpful. I am considering building this for my seeds as I am using the 4 foot folding table now; and it is not ideal. I am growing 2 varieties of eggplant, a heat-resistant hybrid tomato called Summer Set, a heat resistant spinach called Galilee, Gnif carrots, Tahitian Melon Squash, Zucca gourd, Sikkim cucumbers, Matt's Wild cherry tomatoes, herbs-dill, sage, lime basil, cilantro, oregano, I'itoi onions, garlic, and Yacon (a South American tuber). So far...

    1 reply

    Reply 2 years ago

    Thanks! Wow all the stuff you're growing sounds great! We've got about 8 varieties of tomatoes -- Arkansas Traveler and Costoluto Genovese are two of our favorites. Mountain Fresh Plus is a good disease resistant hybrid that was developed here in NC that we grow as well. We've also got 6 varieties of peppers (mix of hot and bell/sweet), two varieties of tomatillos (one is purple), yellow squash, zucchini, corn, watermelons, cucumbers, beans and field peas (much of which we'll direct sow).

    Out potatoes, lettuce, carrots, and some of the cabbage and broccoli we started are doing well, but we've never had much luck with spinach. We'll have to try the Galilee variety you mentioned though! We've never tried Yacon, but we usually grow a good bit of sweet potatoes. Not sure how they compare. Good luck with all the plants!


    2 years ago

    This is really well done. Great detailed tutorial, nice work! :)

    1 reply