Unique Planting Opportunity

[CaptainsLS]

We are redesigning the entire landscape for a Nursing home that has been un-maintained for a number of years. I’m now in the process of looking at the rear (fenced-in) courtyard. Unfortunately there is a large HOT water tank that feeds the kitchens supply located in this area. Even worse the lids are 3.5’ above grade. It looks like a raised septic system if you will.
My initial plan was to build a dry stack retention wall around the tank to level out the area and fill over the tank with massed plantings. The tank is HOT water, and never accumulates more than one inch of snow over it even in a 20” snowstorm.
Essentially I have a raised “heated” planting bed I think. I’m in zone 6 (Cape Cod, MA). I’m looking for feed back about the use of plants that don’t conform to my zone in this area. I’m not familiar with some of the more southern plants. Ideas, comments, cautions? :noidea:

[ClearValley]

Although the roots may react to the "warmer" soil the foliage will most likely get hammered by the colder air if you use plants from a more southern zone

[ClearValley]

Would you actually be putting soil over the tanks and how deep?Sunny or Shady

[CaptainsLS]

The area is extremely well protected from the wind, and has full sun. Will some plants be more receptive to these conditions than others?

Edit: I believe I have about 2-3' of soil over the tank.

[ClearValley]

I would stick to plants within your zone:Think of the warmer soil as being a warmer then usual winter. Plants will stiil go dormant and can react poorly to an extreme cold snap.

Try to use terminate growth plants if using evergreens. Although I may lean more toward decidous which will decide their own growth cycle based length of daylight hours and won't suffer winter poundings.Hardy pPerennials such as dayllies,liriope,baptista,for example might do well.
Shrubs that look enmasse and stand sun: abelia (Compacta or Edw. Goucher)MardiGras is a cool variegated variety.
Deutzia Nikko is a nice low grower Charodonay(sp?) Pearls has more height .Physocarpus/Ninebark colors are nice and work well with the others mix in a few
spirea perhaps little princess or Anthony Waterii
I'm not thinking real well tonite but this combination would give alot of foliar diversity and pretty spread out flowering time frame...PS my spelling rots!!!

[Grn Mtn]

what happens if the tank leaks or needs repair once its under soil?