Starting Seeds Indoors

Starting Seeds Indoors

Posted by subu9213 | On :January 12, 2013 | No Comments

For the highest % of success of eating something from your garden, buy an established plant and transplant it into your garden.  In a future post we’ll discuss some secrets that make transplanting even more successful.

But today we’ll discuss germinating seeds indoors, for transplanting later.

The advantage to this is that you have much greater control over the exact variety of plant you want (vs. being at the mercy of whatever the nursery happens to be selling) as well as how mature the plant is at the time you transplant it.

The disadvantages are that it’s more work, introduces new challenges to your gardening experience, and initially may require you to purchase new equipment.

As a general rule, plant your seeds indoors 8 weeks before they should be transplanted outdoors.  However, you may learn to modify this (shorter or longer) based on your actual results; for example, you may start tomato seeds in December even though you won’t be transplanting them until the end of March.

There are lots and lots of products with very convincing ad copy and testimonials that may convince you to spend significant dollars on seed starter kits (or domes or mini-greenhouse-whatevers).  Just remember that if your device has, say, 30 compartments for seedlings, you need to make sure everything you’re planting has similar germination rates, because it’s very difficult to remove some (when they need to be moved to a bigger home) without disturbing the others.

I personally like 3 oz. paper cups.  I also buy potting soil, even though you theoretically can use your own soil.  This is because I’ve never had good success using my own soil, and relatively speaking, it’s a minimal investment. Used containers and non-packaged soils are exceptionally prone to carrying diseases which tender seedlings are exceptionally susceptible to.

I poke a 1/8-1/4” hole in the bottom of each cup, then fill it a little over 3/4 full with moist potting soil (you risk having your seed dive to the bottom of the cup if you place it in dry soil and then water it).

If these are new seeds, I put 2 in each cup.  If they’re last year’s seeds, however, I put 3-4 in each, as the germination rate might not be so great.  Top it off with about 1/4″ fine (not coarse) vermiculite, then water it gently.

Note that the ultimate goal is one plant per cup.  I plant at least 2 seeds because I can’t risk having the lone seed I planted not germinate.  If more than one comes up, I let them grow for a week or so until I can determine which is the strongest/healthiest, then snip the others.

Place the cups in plastic trays, and water the trays, not the cups (they will wick up water through the hole in the bottom).

Now comes the (initially) expensive part: place these trays about 6” under a fluorescent lamp.  I use one standard fluorescent bulb and one special grow bulb, but according to all I’ve read, standard bulbs are all you need for germination.  If you have a window sill with access to lots of sunlight in the winter you can use that, but in my opinion there just flat aren’t enough hours of daylight in winter; I give them 24 hour light until I see the first sign of germination; after that, 16 hours light and 8 hours sleep.

I also warm the soil with a homemade heat mat: I ordered 12” wide Flexwatt Heat Tape from  It works great and you can order just the length you need.  I laid this on a wooden work bench and covered it with leftover ceramic tiles to moderate/disperse the heat.  It is plugged into a timer set to 15 minutes on, 15 minutes off, as being left on longer can actually make the potting soil too hot.  Most seeds and young plants love warm soil and respond really well.  Read your seed packets, however!  Some seeds will only germinate in cool soil!

Once the seedlings develop stems and leaves, you need to provide them “booster seats” so their leaves are always within 2” of the light; otherwise they will grow unnaturally tall and skinny by trying to stretch up toward the lamp.  At this point you also need to ensure the soil is not too damp and that the top of the soil is dry, as seedlings are very prone to damping off (fungal disease).

Here is a ridiculously staged photo of my seed-starting set-up, showing the lamp, the bench, the ceramic tiles (with one removed to show the heat tape), and seedlings in their little paper cups.

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