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March 12th, 2013
Successful seed-starting takes infrastructure, be it a tricked-out heated glass greenhouse or a fluorescent shop-light setup in your basement. Either extreme–or anywhere in between–can work beautifully. However, in my experience, the solutions that are most likely to be implemented by busy gardeners are those that feel accessible and do-able in occasional spare moments.
This post covers one such solution: a cold frame constructed from easy-to-find, fairly inexpensive materials.
I’m a huge fan of cold frames. Not only do they hold miraculous quantities of promising green growth within their simple walls, they also are easy to build and will happily bring through the winter many servings of cold-hardy crops like spinach, scallions, tatsoi, and mache. Here’s a cold frame that a reasonably handy person with some power tools can put together for about $100 with materials from a local lumberyard (or, unfortunately, big box store–see below). In one season alone, you can easily produce several hundred dollars worth of seedlings in this frame’s roomy 32 square feet.
- 2 pieces 8-foot-long, 26-inch-wide SUNTUF polycarbonate panels — $40
- 2 packs SUNTUF closure strips — $10
- 1 box SUNTUF screws — $6
- roll of tape sealant (often used for metal roof panel overlap joints and similar) or some silicone caulk — $10
- 2 pieces 8-foot 2×12 SPF lumber — $20
- 1 piece 8-foot 2×8 SPF lumber — $8
- 7 pieces 8-foot 2×2 SPF lumber, as straight as you can find — $13
- exterior-grade drywall screws: 1-5/8″ and 3″ — $6
- Hinges – $6
- Circular Saw
- Drill with 3/16″ drill bit, Philips head driver bit, and 1/4″ hex driver bit
- Optional but makes things a little easier: Chop Saw
All of these materials can be obtained from a local lumberyard, with the probable exception of the SUNTUF items, which can be obtained from Home Depot or Lowe’s. I like to give as much of my business as possible to my local lumberyard, Williams Lumber of High Falls, as I appreciate having a locally owned lumberyard so close to home. I want to support them. Unfortunately, they don’t stock clear plastic roof panels of any kind, and since the point of this project was to concoct a quick-and-accessible cold frame, I bit the bullet and braved the strip of sprawl on Route 9W outside Kingston to get the polycarbonate cover. (Note that these panels are lightweight and long–they require a truck to be transported–with some sort of bracing to protect them from blowing away in the wind. Or, you can have the staff at the box store cut them each in half to fit them in your car–see below.)
Once you’ve assembled your materials, here’s what to do:
- Cut each SUNTUF panel in half so that you end up with four panels that are each 26″ wide by 48″ tall. This is best accomplished with a circular saw, though tin snips will also do the job.
- Arrange the four panels so that they are spread out across a flat surface with the last rib on one panel overlapping the first rib on the next. Try to get them as straight and square as possible.
- Measure the distance from the bottom of the first space-between-two-ribs to the bottom of the last space-between-two-ribs. This should be somewhere in the neighborhood of 8 feet. It won’t be exact, but that’s okay.
Make the Frame for the Lid
- Miter cut the ends of two of the 8-foot 2x2s at 45-degree angles, like a picture frame’s corners.
- Cut one of the other 2x2s in half. Miter cut the ends so that the long edges are 48″, like a picture frame’s corners.
- Attach the 2x2s at the mitered corners by pre-drilling to prevent splitting and then attaching the ends together using 1-5/8″ screws or similar. The result should be a giant picture frame, basically.
- Cut another 2×2 to about 93″ in length. Don’t cut it too short! Place it in the center of the frame, centered 24″ from top and bottom corners. This creates a middle horizontal support parallel to the other long sides of the frame; this will prevent the frame from sagging under the weight of adhered interior dew or exterior snow loads.
Finish the Lid
Using the drill bit, pre-drill holes in every other “valley” of each panel’s ribbing along the top and bottom edges.
- Place strips of tape sealant along the top surface of the short sides of the frame. (Or, use silicone to seal this seam after step four. Place SUNTUF closure strips along the tops of the long sides of the frame.
- Line up the panels on the frame so that they are overlapping and cover the entire frame, setting them on top of the closure strips. Set the final “valleys” set so they are resting on the tape sealant (or, again, you can fill this seam with silicone caulk). This won’t be a perfect match–the edges of the valleys will touch the sides of the frames, but they won’t rest on it nicely. This is okay. Just be sure this gap is sealed (it may take a few layers of tape sealant, some applied after the cover is attached.
- Attach the panels using the SUNTUF fasteners and the hex-head driver bit.
Make the cold frame box
- Cut one of the 8-foot 2×12′s into 2 45″ lengths.
- Using a straight edge, draw a line from the top corner of one end of the length to a mark at 7-1/4″ from the bottom corner of the other end. Cutting on this line will create a side to the cold frame that will slope exactly from the rear 2×12 wall to the front 2×8 wall.
- Using a circular saw, cut along this line. Be careful–it can be tricky to perform this cut, as it’s something of a ripping cut that sort of follows the grain.
- Repeat for other 45″ length.
Position the pieces of the cold frame. The two 8-foot pieces of lumber are parallel, with the two 45-inch pieces of sloping lumber forming the sides, with the un-ripped side up. These smaller pieces should be “inside” the 8-foot pieces so that, when sandwiched, the entire length of the side is 48″ (including the 1-1/2″ for the ends of both the rear and front walls).
- Pre-drill holes and attach all sides of the frame using the 3″ screws.
- Half-way down the short sides of the cold frame, attach a spare piece of wood to the inside top edge, flush with the sloping surface of the side.
- Flip the cold frame over. Cut one of the three remaining 2×2′s into 2 45″ lengths. Match these up with the undersides of the lumber that makes the frame and attach with the 3″ screws. This will be the “ground floor” of your cold frame that will slowly rot over several years. After it’s rotted, simply detach and replace with a new “ground floor.” The rest of the cold frame will last for about 20 years or so if left out–maybe more if stored well when not in use. (The ground floor is not shown in the accompanying photos.)
Put the Lid on the Cold Frame
- Set the lid on the cold frame, matching up the corners with the frame.
- Attach to the cold frame using a couple of long rectangular hinges and short screws.
- If the lid does not sit squarely on the frame, purchase and install a latch to hold it snug.
VOILA! A functional cold frame that can be built in an afternoon for around a hundred bucks. Fill it with trays and go to town! You’ll find endless uses for it.
Filed under How-to, Seed Starting 101 | Comments (16)
February 25th, 2013
Starting seeds early, when done right, is one of the most satisfying aspects of gardening. To see young, green shoots perk up through the soil while winter carries on outside is incredibly gratifying. It’s as if spring begins as soon as the first cotyledons (first leaves) pop open. It’s also an essential part of growing tomatoes, peppers, eggplant, and other crops, which otherwise don’t have a long enough season in northern climates to mature much ripe fruit.
For the home gardener lacking a heated greenhouse, there are two main ways to start seeds under protection: indoors or in a cold frame. We’ll take a look at both strategies.
STARTING SEEDLINGS INDOORS
Our friend Kerry Trueman demonstrates her own indoor seed-starting technique–with decopage!–in this great video. Check out retrovore.com for more New York-based food and gardening content.
For many gardeners, starting seeds indoors is the preferred, tried-and-true method. However, despite what most people believe, to be successful requires more than just a sunny windowsill. Successful indoor seed-starting requires the following components.
- WARMTH. Most seeds will germinate within a fairly wide range of different temperatures. However, the swiftest germination takes place for most seeds of annual crops when soil temperatures are in the 70-80 degree range. The most notable exception to this is lettuce, which prefers a cooler temperature range of 60-70 degrees. Warmth is usually provided either by locating your seed-starting set-up strategically (near a wood stove or radiator, usually) or using a propagation mat, an electrical device that supplies bottom heat to the undersides of trays. In most cases an interior temperature of 60-70 degrees is not warm enough for quick germination, but seeds usually will germinate eventually (lack of supplemental heat is especially detrimental to peppers and eggplants, both of which are REALLY SLOW to germinate when left at room temperature).
- MOISTURE. Seeds sown indoors are easy to water, but be sure to locate the seeds somewhere where you’ll be free to water liberally when needed. Watering can create drips and mess, and if you put the set-up in a pristine living room you risk being too precious about things to get done what has to get done.
- LIGHT. For nearly all varieties (except lettuce), a sunny windowsill just doesn’t cut it. There do exist rare, due-south, full-sun, bay windows that just might cut it. But for most situations, extra light is necessary when starting seeds indoors. The most affordable way to provide this is to purchase a shop-light fluorescent fixture and suspend it within 1-2 inches of the emerging seedlings. Run it for 12-14 hours every day. And if you can set it up against a window, so much the better.
- HARDENING OFF. Seedlings grown indoors are incredibly tender and sensitive, as they are subjected to neither the temperature swings nor breezes found outdoors. If you were to move them directly from the house to the garden, the shock would severely damage or kill them. Indoor-grown seedlings require full hardening off: a period of about 3-7 days when the seedlings are exposed in increasing doses to the natural elements. Start with a couple hours the first day, and gradually work your way up to 8 or 12 hours before transplanting them. Be sure to take on this process at the correct time for each variety.
Summary: Starting seeds indoors is convenient and accessible to all gardeners. Little time or money needed for infrastructure. Supplemental lighting is almost always necessary: don’t skip it! Seedlings grown indoors are ultra-tender and require careful hardening off.
STARTING SEEDLINGS IN A COLD FRAME
A cold frame is a simple structure placed in the garden that features structural sides (usually made of wood) and a top made of a transparent material such as clear plastic or glass. Starting seeds in a cold frame eliminates several of the difficulties of starting seeds indoors. However, it requires a small investment of time and money in the construction of the cold frame and careful attention on cold nights. Here’s a brief run down of what you need to know for successful cold-frame seed-starting.
- WARMTH. From early March on, cold frames warm up significantly almost every day. When unvented, the interior temperature can easily top 90 degrees on a sunny day. The soil in seedling trays or soil blocks absorbs much of the solar radiation and heat, and the soil easily reaches temperatures that initiate seed germination. However, on cold nights the cold frame provides only 10-15 degrees of protection (depending on wind and the previous day’s high), so providing a bit of heat to stave off frost overnight is sometimes necessary. Sometimes throwing some old wool or polyester blankets on top can be enough; sometimes running a light bulb or Christmas lights within the box can do it. Generally some extra heat is wise if the outside temperature is predicted to drop below about 26 degrees and the frame contains frost-sensitive seedlings such as tomatoes, peppers, eggplants, basil, and certain flowers. (A cold frame with only brassicas and lettuces and greens will need no additional heat.) On sunny or warm days, venting is necessary–anything from cracking the lid to removing it entirely. Keep a thermometer handy: experiment a bit and you’ll get the hang of it.
- MOISTURE. Seeds sown in a cold frame can be watered with abandon–no mess to worry about. Do monitor the seedlings at the end of the afternoon, as solar heat and breezes from venting can cause rapid moisture loss on a warm or sunny days.
- LIGHT. When you use a cold frame, the mighty sun takes care of your light requirements: no supplementation is necessary. Just be sure to place the cold frame in a spot that gets full sun exposure. (Keep in mind that leafless trees will fill out and shade the cold frame before tender seedlings can be put in the garden.)
- HARDENING OFF. Seedlings grown from the start in a cold frame require almost no hardening off, as they are exposed to temperature swings and breezes from a young age. Maybe give them one or two days of resting in a semi-protected spot outside of the cold frame before putting them in the ground; other than that, you’re golden!
Summary: Cold frames provide an ideal environment for seed-starting. Gardeners are assured ample natural light and need not bother with much hardening off before transplanting. Cold nights are an issue: gardeners must monitor for sub-26 temps and provide additional insulation or supplemental heat on those nights if frost-tender crops are in the cold frame.
Filed under How-to, Seed Starting 101 | Comments (5)