Difficulty in Growing Oregano From Seed

My question is that my parents have a greenhouse business and we have problems in getting oregano to germinate, so we have to buy it in. We live in Kalamazoo, MI, USA, therefore the area is not too different from where you live. Thus I thought you might be able to help.
I read that the plant does not like to be fertilized. We add fertilizer directly into the watering system via pump, so everything gets it five days out of seven.

Oregano likes sandy soil and heat. We too have an in-line fertilization program, but have to be careful not to overdo it for plants such as oregano. The seedlings are very fragile to start with, since the seed is very small. The Pro-Mix used by many nursery people may be too water retentive and rich -with the slow-release fertilizer that is included in it.