Yes, it sounds like these hydrangeas are planted out of zone and winter kills the stems. When Spring arrives, new growth comes from the base/crown. If the hydrangeas blooms on old wood only, you do not get blooms on such a year. If the hydrangeas bloom on old and new wood, you do not get early blooms from the old wood but you should get bloomage from the new wood by late June or in July.

This often happens with mopheads and lacecaps that are planted in cold zones. Or when temps get warm and awaken the plant from their winter slumber, only to get hit by freezing temps. Mopheads and Lacecaps that are rebloomers might help as these will develop flower buds from new stems also. You may have mopheads that bloom only on old wood so once the flower buds that they develop in July get killed by winter, you get new growth and no blooms. I would try to see if applying winter protection in the Fall helps some. Or plant hardy hydrangeas like Annabelle-types or any of the paniculatas.

As far as pruning goes, you can prune the dried out stems all the way down if theyhave not leafed out by May. And as far as as the soil goes, just do the usual (1) keep them mulched with 3-4" of mulch up to the drip line, (2) fertilize in Spring after your average date of last frost and (3) amend the soil -if necessary- to keep the soil pH in check.

If you insert a finger into the soil to a depth of 4" (not counting the mulch) and the soil feels dry or almost dry then water (1 gallon of water).

You can then do this early every morning for 2-3 weeks. When you water the plant because the soil feels dry, also make a note in a wall calendar. After 2-3 weeks, review your notes in the calendar and determine how often you were giving the shrubs 1 gallon of water. That should be something like watering every 3 days, every 4 days, etc. Then set your sprinkler to provide 1 gallon of water on the same frequency (every 3/4/etc days). If temperatures change by 10-15 degrees and stay there, use the finger method again to determine if you need to tweak the frequency of your waterings.

What growing zone are you in? It looks like you have some green buds coming out of the stalks. Make sure you do not trim the stalks that have green buds. By mid-late May you will be able to tell where your growth ends and what will not produce any growth. Trim at that time. Trimming incorrectly results in no flowers. Have you tested your soil? I recommend Jack's 10-30-20 follow the package directions. This should help compensate for soil deficiencies you may have. You can expect hydrangeas to need watering when it's hot and dry. They prefer morning sun to hot afternoon sun. Does the brick wall next to your plant get hot? Good Luck.

Leaf edges turning browning and getting bigger can either be insufficient water or some small insects. If you insert one finger into the soil to a depth of 4" and it feels dry or almost dry, give it 1 gallon of water.

Get any fertilizer that you like. They REALLY respond to composted manure but then again, so do some of my dogs. Ha!!!! One application of a general purpose, slow-release fertilizer should last about 2-3 months. And they are not heavy feeders so do not go overboard like with roses. A single application in the northern states is enough for the whole growing season. Then you can add coffee grounds, liquid seaweed, liquid fish or compost but be sure to stop by the end of June or they may stay in grow mode thru the first frosts in the Fall. Last year I gave them cottonseed meal because that is what I had most of. This year it is composted manure. And unless your soil is sandy and poor, they will not "die" if you forget to feed them at all for 1-2 years. I forgot once and could not tell the difference.