Sowing Seeds Indoors in Late Winter / Early Spring

Sowing seeds indoors before Spring starts – done right – is a cheap way to have top quality plants ready to go as early as possible.
New gardeners will learn so much about plants and soil from it, and experienced gardeners who like to experiment value the opportunity to test the limits of their favourite plants, as grown in their particular garden, by planting a small batch outside every week or two and observing the results: sometimes it goes well and have your first flowers or vegetables before anyone else, and sometimes it all gets frosted and composted, so it’s easier to start off simply following the instructions on the packet!

While it is true that all you really need to get begin is some potting mix, any old tray with drainage holes, and a nice sunny South facing windowsill (a mirror right behind your seedlings is helpful but hard to arrange, so a reflective foil over cardboard backing is better than nothing for maximising light around your seedlings) you are unlikely to get the best results that way, and it quickly becomes impractical when growing lots of seedlings.
For an easy life and consistently excellent plants, accessories like seed trays, heat mats, and (unless you have a greenhouse) grow lamps are essential for the serious germinator.

Ben at GrowVeg has a couple of excellent videos on growing vegetables from seed – there really is no difference in growing veg or flowers at this stage. Ben does have a nice greenhouse, so he doesn’t really go into grow lamps, more on those below.

Ben’s overall guide to sowing & potting on seeds:

Ben’s dedicated guide to germinating seeds (i.e. all the stuff before they sprout):

And Ivor has some extra tips on dealing with masses of seed trays for planting seeds en masse: we agree with his March Mission Statement “In March, I try to sow as much as I can!”

Most of us don’t have the luxury of a greenhouse, and probably not enough sunny, South facing window space to comfortably grow everything we want.
Seedlings must have plentiful light in order to grow strong, stocky stems. A healthy new seedling is typically short with leaves appearing in close succession, but if they are forced to search for light, they will grow tall and thin, with a lot of stem between each set of leaves, which could end up too weak for your purposes: stems will snap or flop flat on the ground as they get bigger.

A normal light bulb is not good enough, you need a proper grow lamp/s, mounted overhead so the light covers your seed trays well.

There are loads of specialist grow lamps designed for plants that are energy efficient, which means they don’t give off a lot of heat.
Very hot bulbs are not good for grow lamps because you have to increase the distance between the bulb and the seedling to avoid melting it, so the seedling gets less light, and you waste money.
However, if you are just trying things out and don’t want to spend much money, any suitably strong light bulb from your neighbourhood bulb monger will serve the purpose of feeding a plant’s photosynthetic needs.
The measurements of light’s strength that matter most for plants are Lumens and Kelvin, which will be printed on the box: you need 1500-2000 Lumens, and 4500-6500 Kelvins for strong plant growth (for comparison, a typical household 100W lightbulb is under 1350 lumens and under 3000 kelvin – too weak).

Despite using products on Canadian Amazon for reference, this video by our favourite myth buster Robert Pavlis is the best we’ve found for an entry-level introduction to grow lamps (I had just made a video myself for you when the dog came in, and the poor soul looked so famished that I had to give him something):

What plants (apart from our Cosmos and Sweet Peas, of course) are you growing from seed this year?

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