I have what I think is a mock orange – quite large deep green leaf and small white cluster bloom.
My question is, it is doing great but has become very leggy and is hanging all over what is planted in front if it. When and how much do I prune out so it will not effect future bloom.
Mock orange (Philadelphys spp.), with its lovely fragrance and long lasting white blooms has naturally a vase shaped form. If pruned every year it will fill in and become a lot denser.
As Mock orange flower on the wood of the previous year (old wood), they are best pruned right after flowering. Thin out crowded branches for good air circulation. You describe yours as “leggy and hanging”, so you might want to shorten those branches by about a third. If it is also overgrown, rejuvenate your shrub by pruning about a third of the oldest branches right down to the ground. It will fill in again. All this will allow more light to reach the inner parts of your plant and enhance flowering.