Seed Starting 101 - Part V

Greg Holdsworth, contributor

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When it comes to seed starting, choosing the right planting medium can make a big difference in how efficiently your seeds and plants receive moisture, as well as how well the medium drains when watered.

Most of the ready-to-use seed starting mixes I've tried have one thing in common – they don't absorb water or drain well. Their light fluffy texture is easy on seeds, but seems to almost repel water. Granted, if you prefer to wet the medium first before sowing the seeds, it'll already be, well, wet. After it dries, however, you may start to see the lack of draining ability I spoke of.

As a result of this, I tend to mix a little compost with the seed starting mix. It seems to add some thickness and weight to it, and greatly helps it absorb water and drain better.

In this video, I do a simple experiment to compare water absorption and drainage. In one container, I fill it with only ready-to-use seed starting medium. In the other, I mixed the same seed starting medium with compost, in a 1 part compost to 3 parts seed starting mix ratio.

The first step tests water absorption by pouring water on the top of each mix, as though you were watering your seedlings this way. Eventually, drainage is tested, by continuing to add water to each container.

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Seed Starting 202 - Preparing Seedlings For Outdoors

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Comments (1)

country_citygirl writes: Greg,

I couldn't agree with you more. The seed starting kit with the pellets that expand when yo buy them was the last thing I used before I started to use my own mixture. I found that I really had to stay on top of watering when using the pellets because the mixture would dry out so quickly, furthermore, it was difficult for the water to penetrate the mixture once it got too dry. So, I had to be careful not to over water my seeds so they wouldn't rot, but I had to make sure that the pellets didn't get too dry either. It was a headache! I found that potting soil and compost worked like a charm. I don't have an exact ratio, I just kind-a eye ball it. I do use more compost than potting soil and it doesn't burn my seeds.

I'll be sure to post photos tomorrow.
Posted: 8:53 am on March 28th

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