most flowering shrubs are setting buds for next year.. right now ...

ergo.. if you cut it all down.. no flowers next year ....

if you dont care about one lost season.. you get a whole new bush next year ...

otherwise.. cut out the largest one half of the branches as close to the ground as you can.. the rest will flower next season.. and next fall.. cut those to the ground.. because in the mean time.. new branches will grow next season.. for flowers the next

google REJUVENATION PRUNING OF FLOWERING SHRUBS... for further info .. add your plant name for more precise info

ken

This is a slow-growing broad-leaved evergreen shrub so treatment may differ from that of a fast-growing deciduous flowering shrub. It is known to come back from stumps but keep in mind growth of this shrub is slow. Similar situation to that with a camellia, in this respect - you can cut it way down and have it live, but it won't shoot right back up quickly.

Once you cut it off you can't put it back.

I had a gappy, leggy, tall Pieris many years ago after it was moved from a struggling sunny spot to a proper spot in the shade. I cut each branch back about 2-3 (or more?) feet all around to thicken it up and even it out. I did this for a few years. It responded well. Very nice and full now.

I usually don't get many blooms above the snow line, but that's okay. Its a great looking evergreens.

Spring or Fall pruning is fine. Summer is generally too stressful. The cuts have to heal and this would be a good low-stress time for the plant to do that.

There may not be much coverage of cuts made at this time of the year. Large stumps will certainly not be covered over for years.

I inherited six 8-10' tall misshaped pierises and over the years practiced on them all kinds of pruning: cut-to-the-ground (6"), 1/3, selective, fall, spring, summer and after 10 years of experiments end results were practically the same- shrubs responded well to initial pruning by sending numerous new shoots from the dormant buds and filled nicely.
However, I learned that yearly pruning is a must, otherwise the 'new' shrub in 3-4 years become the same 'old and misshaped' plant.
Re: slow growing. Yes, it's true when we talking about newly planted pieris, even if it was in a large pot or B&B it will grow at 4-6"/year at the very beginning, but for old plants, with very established root system, 'cut-to-the-ground' treatement produced a 5' tall shrub in 6 years. And that with an annual shaping/pruning.