You posted to the wrong forum.

what is your personal goal .. immediate satisfaction.. or patience ... and your answer lies within ... if budget is irrelevant .. then fill it in ASAP ... why wait i dont see air flow as an issue.. since you want them to fill in completely anyway ... bottom line.. you are overthinking it... just tell us what you want.. right now .. dont think about it .... come on.. we are waiting.... ken

As to how far apart they should be planted, using the species name for the specific privet you are getting (I see the Arbor day site says Ligustrum x ibolium), you should be able to find the mature size of the plant on the internet. Using that to determine how far apart; as an example, if the mature size is 6 feet wide, then plant them six feet apart (or closer if you want a tighter hedge sooner but they will crowded themselves eventually). Looks like Arbor Day says the plants will be 1 to 2 feet tall upon delivery and mature spread according to them is 4-6 feet. Another site says 6-8 feet wide and "this hybrid is a cross between L. ovalifolium and L. obtusifolium" (for those that are interested in the parentage). Ligustrum obtusifolium has some reported invasive tendencies in some northern states as noted here. Here is a link that might be useful: Mobot site with height and width numbers

Thanks lisanti! No, the soil doesn't look any different than over on the right. All the plants were planted at the same time and from the same batch of plants from the same nursery. I suppose I could try planting a new one or two but while not expensive, they aren't cheap for a good size plant. I'd hate to plant new ones and have the same problem and be right back where I am in a few months or next year. I guess I was hoping for a magical cure that will fix the problem but I guess I'll need to try something like this eventually.