Maurice - Root disturbance makes real sense to me. I have lost several seedlings since amending the raised bed they were in. Apparently they had a root system too small to recover and quickly died.
I have another question ...
How do daylilies do competing with other plant roots? I ask because I have some planted next to an Oak tree. A few of those have disappeared, too. I dug around in the dirt and found roots that I am sure belong to the tree. (sigh) Never enough ground space when you have trees! Some of my daylilies have a pretty massive root system, can those survive around other larger plants or will they eventually die off due to the competition?
And another question ....
Can producing pods on a seedling eventually kill it? I am talking about a small seedling with a single fan. Does it tax the plant so much that it doesn't recover and eventually dies that same season?
All these things I am taking note of in my different seedling beds. I often feel like my yard is a virtual experiment!
