If you won't be there to monitor watering needs, I'd have some kind of irrigation system added to water at least once a week (twice a week would be better) during the growing season as you have already found out that they don't do well if there is a drought of any kind. A simple micro irritation system or a "leaky" hose with a battery operated timer may be all you need.

Seashell mulch - that is up to you as it seems to be a personal thing. Any mulch beats no mulch...

As for winter, I'd see what others do in your region for protection if it is needed at all.

I agree with hcmcdole, Cappy. #1 task is to address the lack of moisture.

If you are also seeing leaf spots, it could be Cercospora Leaf Spot. It crops up in the summer months. Rust is another possibility but the spots are more orange-y and smaller.

Cercospora cannot be cured but improves if you use clean cleaning practices: water the soil (not the leaves) early in the mornings; do not crowd the plant near others (separation of plant leaves improves air flow which makes the fungi dry and uncomfortable); pick up all plant debris from under the plant; dispose of leaves/blooms of an infected plant in the trash; drought may improve conditions temporarily; spots will become more visible in the Fall. Fungicides can be used but the spots usually become visible just as the leaves are about to dry out and just as the plant is about to go dormant... so you have to wonder if you want to use $$$ fungicides as the leaves are going to brown out. Replace the mulch if the leaf spot infestation is large. The worst leaves can be pruned at the petiole and thrown in the trash.

Overhead watering can also helps rust develop.

See this link for more information:

http://www.aces.edu/pubs/docs/A/ANR-1212/index2.tmpl

You can start adding aluminum sulfate as soon as possible since the changes are gradual (slow). Follow the label directions. Of course, first check if the soil is already acidic at the summer house and if not, begin applying a/s... forever (if you start and stop, the soil will loose its acidity). Try not to go too overboard applying a/s since a lot of sulfur can burn tiny roots. You can continue applying a/s thru the winter months (I assume the soil does not freeze up there in the coast).

Once the plant goes dormant in the Fall, you can reduce waterings to about 1 gallon per watering per week (or every other week) if it is dry. Continue providing water thru winter (if the soil does not freeze) until leaf out in Spring if it is dry. If your soil is sandy, you will need 50% more water than normal so 1 gallon becomes 1.5 gallons in sandy locations.

Luis, I don't know about NJ's winter weather but I quit watering once the weather gets cold in Atlanta because we usually have plenty of rain during fall, winter, and spring months. I do let my hoses, sprinklers, splitters, timers, and nozzles outside which usually results in some damage to splitters and nozzles from freezes even though I feel like I have bled off excess water in the lines.

Indeed, if it is dry, you should water (provided the soil does not freeze) but if you get moisture then enjoy not having to water. ;o)

Thank you all... I am getting rid of the shells and will put pine bark mulch. In the spring will put in a timed sprinkler.

Good luck with the summer house!