Potting Soil vs. Potting Mix


| 4/24/2015 3:08:00 PM


Tags: potting mix, Earth boxes, starting plants inside, Bruce McElmurray, Colorado,

earth box

Every once and a while I do something wrong and often post it on this blog. Not to embarrass or humiliate myself, but I get it wrong and hope by revealing my mistake it will help others to not make the same error. Such was the case recently. Our weather looked like it may be quickly improving for the best and that we may be getting an early summer. That presented what appeared to be a good chance to get some of my garden plants started indoors to later transplant outside. When the growing season is as short as we have it is always a bonus when we can jump start the season by giving plants a head start inside.

I had 24 zucchini plants doing real well inside as well as some carrots. Just as I thought my plants were about ready to transplant outside we received a series of snow storms and very cold nights. We ended up with a total of 48” of snow over the next three week period which meant my gardening plans were going to require major alterations. Planting outside was now out of the question so instead I decided to put my earth boxes to use. I had not used them in a few years. They are boxes that have a water reservoir in the bottom where the water wicks up from the bottom and the plant roots are fed the appropriate amount of water to enhance their growth.

My assumption was that I could transplant the seedlings in the earth boxes and put them in my shop which is heated. I also put a grow light over them to keep them going until the snow melted and they could be safely taken outside. The weather had been so nice that the spinach I planted at the end of fall was already sprouting and growing outside. On my next trip into town (45 miles one way) I went to a local garden store and advised I needed some soil for my garden boxes. I was told that a certain type of soil was excellent and it was also organic soil. I might add that it was also very pricey and it was what the sales person said they used in their own earth boxes. In fact it was so expensive that I only bought two bags instead of three which I had intended to purchase.

I brought it home and filled three earth boxes and transplanted the seedlings and situated them under the grow light. I added several gallons of water and believed I had salvaged my seedlings. They started out real well and I was confident that I had salvaged the plants. After a few days I noted that they did not seem to be growing like I thought they should. I also noticed that I had several bites that looked much like mosquito bites. Then one day as I was adding water to the boxes I noted something flying around and sure enough it was a mosquito. Since it was still freezing outside and there was 2-3 feet of snow remaining on the ground I knew they didn’t come in with me from outside. This is my woodworking shop and I have never had a mosquito in the shop before. At this altitude we normally don’t have a mosquito problem. Then I observed a mosquito that flew out the watering tube in one of the earth boxes. The potting soil clearly had mosquito eggs in it and somehow they got into the water reservoir and were hatching.

There was no choice but to take the now faltering plants outside where they quickly froze. They were just barely holding on anyway and would not have made it much longer. When everything else fails sometimes it is best to go to the directions which is what I should have done in the first place. I finally found the manufacturer direction booklet that came with the boxes many years ago. As I read the directions it clearly stated I should use potting Mix not the potting soil. It was apparent that the potting mix wicked up the moisture from the bottom to keep the seedlings roots wet where the potting soil did not do that. The manufacturer clearly knew what worked in their earth boxes and what didn’t work. Potting soil did not work which is why the manufacturer specified potting mix.




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