I have to start cucumbers and many other seeds in my greenhouse due to our soil temperatures. Never had problems with root rot. I do use a sterile seed starting mix. If I plant in the ground the seeds mostly will not germinate and eventually rot. In Wisconsin where I grew up we always planted directly in the ground. Even though zones are similar to here in Idaho the nights are warmer in Wisconsin, thus the soil is warmer.

I have been eating and giving away cucumbers from what I grow in containers. Also my dogs love them too. In fact my Labrador Retriever just helps herself. :o) Love your post