Kathy,
That's an interesting question about spraying Messenger on seedlings; it should be posted on RHA forum. My seedlings get no fertilizer, superthrive, messenger until they are maybe 6 wks old when they get a small amount of osmocote. Seedlings grow very well without any chemical help.
100 people will give you 100 different opinions!
dave

Kathy,
Your question about applying Messenger to seedlings has been posted on RHA forum (rosehybridizers.org).

thank you Dave.
Kathy

I'm with Dave--no chems on babies. In fact, as few chems as possible. I use Superthrive when I pot up/transplant, just a few drops in the water when I water them in. I fertilize with an all-purpose organic fertilizer twice a year. That's it unless I diagnose a specific nutrient deficiency. More is not better.