Plant spacing

Hi,

Can someone tell me please, how far apart should l space out my Petunia Hybrid Double plants when l start planting out next weekend. Thank you.

 

If they're F1 hybrids, you can expect them to be vigorous so I'd give them about 12 ".

I don't think the odd inch either way is critical, though. I usually just use the length of my trowel as a rough spacer.