Color me optimistic, but I’m calling “spring on its way.” If someone tells me it’s still winter, I’ll call them a stinkin’ liar. It’s spring and this means it’s time to start seeds in preparation for the growing season. It comes quicker than you think!
But along with being optimistic, I am also not rich enough to buy those pre-packaged seed starting kits I’ve seen in the store. I’d rather spend my money on other things like a really nice microbrew once in awhile. I also have a small house (about 800 sf total) and not much room to construct the seed-starting nursery to rival the Colosseum that I’ve seen other people manage. So my seed starting set up has to be cheap, productive, and take up little space.
Luckily, I met all of my criteria for a total cost of about $20 (not counting the cost of seeds). And over half of that cost was for a clamp lamp and a grow bulb, which I can use again. That $20 went towards constructing a heat bed, which is a way to supply warmth to the roots of developing seeds and enhance germination, and the starter medium in which I planted my seeds. The rest of the material was either recycled or used. Here’s how I did it:
HEAT BED HOW-TO
What you need:
- A sturdy container for the project (I repurposed an unused plastic bin)
- Non-clumping kitty litter or sand
- Indoor-outdoor rope or string lights
- Egg cartons (or your seed-starting container of choice)
- Seed starting medium (potting soil will work)
- Clear cover (plastic or glass) for the container
I already had an unused, under-the-bed plastic storage bin, measuring about 17″ by 36″, which was going to serve my purposes well. The plastic bin served as the base for my heat bed.
I took the bin and placed it on a bench in my closed-in porch. Then I poured half of a large bag of kitty litter into the bin and smoothed out the surface. Next, I laid one string of lights (with a 33′ string length and 100 bulbs) on top of the kitty litter, making sure the lights were mostly evenly spaced in the bin. Lastly, I covered the lights with the rest of the kitty litter and plugged the lights in to allow them to start heating the litter (again, you can also use sand…whichever is cheaper in your area).
You can use a wide variety of containers for your heat bed, including used flats from nursery centers, sturdy cardboard boxes, or even wooden boxes. The box just needs to be deep enough to hold a layer of kitty litter/sand and lights, and sturdy enough to withstand watering your seedlings for several weeks. Aim for about a 2- to 3-inch layer of litter or sand, with the lights layered in about half way. That will hold the soil temperature at about 92F, if your ambient air temperature is in the upper 60s or low 70s. For most seeds, a 92F soil temperature is about right to enhance germination. Just make sure that the lights you use (be they rope or bulb-style) are for outdoor use; you’ll be watering your plants and your lights need to withstand that.
With my heat bed warming, it was time to plant some seeds! I had saved egg cartons for several months and used them as my seed-starting pots, separating the lid with a knife. The lids are great for starting seeds that need to be thinned after germination, like lettuce, and the carton portion is great for your other seeds. When the plants in the cartons are large enough to be planted into larger containers or transplanted outdoors, I take scissors and cut the whole egg carton apart into its individual pots and just plant the thing, carton and all (it will degrade in the soil).
Yes, you can use Styrofoam egg cartons for this, and they will retain moisture better for germinating seedlings. However, if you cover your heat bed (as you should) with a layer of clear plastic or glass to retain the all-important humidity for your seeds, this won’t be as much of a problem. Also, you can’t plant the Styrofoam directly into the garden, which means disturbing the roots of your young plants when you remove them. Lastly, there is some serious question about the Styrofoam starting to degrade and leaching the chemicals into the seedling soil, which will ultimately make its way into your garden. To me, the benefits of Styrofoam cartons (better moisture retention) are alleviated by covering the heat bed, which you have to do anyway.
Lastly, your heat bed will need a supplemental light source, unless you’re lucky enough to have a true greenhouse. Seedlings started indoors without proper lighting will just end up spindly and less healthy; it’s worth the cost to buy a supplemental light set-up to give your seedlings the best start possible. And such lighting doesn’t need to be expensive. I bought a clamp lamp and a high quality grow bulb for about $14, and I can use this season after season (depending upon how long the bulb lasts, of course).
I used an organic seed starter mix for my seeds, filling each egg cup to full. It’s a good idea to invest in a seed starter mix, which is formulated for the special needs of germinating seeds but I’ve known people who use regular potting soil and that works, too. I only needed 1/2 a bag of mix for six dozen egg cartons, and it cost $3.50 a bag for organic. I have plenty of mix left for other seeds I’ll start in a few weeks or so.
After you have your mix ready, just follow the directions on the seed packets about how deep to sow each plant, but a general rule of thumb is to plant a seed three times as deep as the thickness of the seed. However, this isn’t always true; for instance, salvia seeds need light to germinate and therefore shouldn’t be buried in the soil at all. So if you’re a seed saver (and you should be) or just don’t have the original seed instructions handy, it’s always a good idea to have in your gardening notes the correct seed planting method for all the seeds in your arsenal. You can also look this information up online.
After my seeds were planted, I simply moved the cartons to the heat bed, watered them all well, and covered them with two pieces of acrylic a neighbor had left over from a project of his own. I’ve tried saran wrap for this in the past and it just doesn’t work. I’ve also saved the clear plastic flat covers you can sometimes get from nursery centers and these work well, too (as was their intended purpose).
This is all fine and dandy, but can all seeds be planted indoors to get a head start on planting? And when, exactly, are you supposed to start the seeds indoors? These are indeed things the wise seed starter looks into before introducing their precious seeds to soil.
INDOOR SOW OR NO?
First, I recommend going through your seeds and determine which ones really need to be direct-sown into your garden after the danger of frost has passed, versus starting seed indoors and transplanting outside. Plants recommended for direct-sow usually do not transplant well, and there can be high mortality rate if you try that route. And the older these plants are, the worse the transplant shock — and subsequent plant death — can be.
But there is some disagreement about which plants are best left for a direct-sow approach, (It couldn’t be easy, right?). For instance, some sources recommend direct seeding melons, but since I live in a chillier clime I’m planting them indoors to get a head start. After the seedlings germinate I’ll transplant them into large biodegradable pots that I can simply place into the soil with minimal root disturbance. There’s nothing wrong with experimenting on your own; horticulture is part art and some people just have a knack for doing what others say isn’t possible.
Plants that are recommended for direct-sow include lettuce, spinach, radishes, cucumbers, most squashes, peas, beans, corn, and carrots. Some flowers prefer direct-sow, too, including sunflowers, nasturtium, zinnia, bachelors button, plus a few others. But again, I’m going to start the zinnias and sunflowers indoors and transplant them. If garden centers can do it, so can I, right??!!
The timing of all this depends upon where you live and what your “last frost date” is. There are different recommendations about when you should sow plants indoors, and they are all roughly related to this date. You can visit the website of your local Cooperative Extension Service for this date. Then, you’re supposed to look at the seed packet and, if you’re lucky, it will say something like, “Sow indoors two weeks before the last frost date.”
But because I am lazy, I just go to this handy dandy resource kindly supplied by the Farmers Almanac (find it here). Just type your zip code into the Location field provided and it will spit you out a nice table that includes lists of vegetables and the recommended date to either start seed indoors or direct sow outdoors in your area. It even includes a “moon favorable date,” if you prefer to use the moon as a guide for planting. It’s a great resource and takes the hassle out of figuring out when you need to time your seed planting.