Plant roots can teach newbie gardeners so much. This season, the roots of my plants have taught me that soil matters. A lot.
Back in January I started my seeds in 100% coconut coir. It was cheaper than peat moss---a 12L brick only cost me 100 yen (roughly $1)---and since it was supposed to have great aeration and water holding properties, I figured I wouldn't need to mix in perlite or make any other amendments. Boy was I wrong.
Everything started out great, but I noticed after several weeks had passed that my seedling growth seemed majorly stunted compared to images of other growers plants that were started around the same time. The culprit was of course the coir.
It would appear that coir by itself should be treated as a hydroponic medium; without a steady supply of nutrients at a correct dosage, plants growing in 100% coir seem to not do very well. What I've learned is to treat coir just like peat moss---if you want to grow in coir like you do in soil, you need to mix it up with compost or castings and perlite/vermiculite. All else equal I have found that a coir mix works better than 100% coir any day and have since adjusted my setup to reflect that. Root growth illustrates this very well.
The tomato on the left (A) was started in coir two or three weeks earlier than the one on the right and fed with 5-5-5 fertilzer once or twice. The one on the right (B) was started in a coir/earthworm castings/perlite mix and has not been fertilized at all. Notice the heavier top growth and thicker roots of tomato B despite not having been fertilized.
My pepper starts have also been doing very well since being repotted (same pots) with the same mix as tomato B above. Previously several of my rocoto were starting to droop and no amount of feeding seemed to make a difference. Several days after repotting however, and they have all started perking up.
With the wonky weather this year and the poor growth I had, my expected plant out of mid-April was completely missed and I am currently planning to plant out the first week of May during Golden Week holidays. Come this weekend I'll need ot figure out which plants go in the ground and which ones to pot up in 3 or 5 gal fabric pots. Here's to hoping the weather clears up!