Flower & Plant Installation in Boston, MA

A planting plan that would work in most of the country runs into four problems here.
There is almost no ground-level soil to plant into in the North End and on Beacon Hill. Most lots were built out to the property line generations ago, and what soil exists is often compacted fill under a layer of brick, not a bed a shovel goes into easily. Installation in these neighbourhoods is usually container-based by necessity, not by choice, and the container sizing, drainage, and soil mix have to do the work that native ground soil would otherwise do.
South-facing brick absorbs and re-radiates heat through the afternoon and evening, and by mid-July a container against a south wall can run 15 to 20 degrees hotter at the root zone than the ambient air temperature. Plants selected for full sun on a spec sheet can still scorch in this microclimate, and containers dry out fast enough that a missed watering day shows by the next morning. Plant selection and container sizing for these walls has to account for the wall, not just the compass direction.
Wind scour becomes a real design constraint on any terrace above the fourth floor. Wind at height strips moisture from foliage and soil faster than it does at street level, snaps soft new growth, and can desiccate a plant that would be perfectly hardy for the zone at ground level. Terrace and roof deck planting above that height generally needs wind-tolerant species, staking or anchoring for taller elements, and a watering schedule adjusted upward from what the same plant would need on the ground.
And the frost window here runs from roughly mid-October to mid-May, which is a longer dormant stretch than most of the plant tags account for and shorter than most Southern suppliers expect. Fall installation has to be timed to give roots time to establish before hard frost, and any tender material — tropicals in containers, for instance — needs a firm pull-and-store date well before the first freeze rather than a wait-and-see approach.
Taken together, these four conditions mean a plant list that’s correct for USDA zone 6b or 7a in the abstract can still fail on a specific Boston site, because the zone rating assumes in-ground planting at street level with typical wind exposure. A container on a ninth-floor terrace, a bed against a south-facing brick wall, and a tree pit in sidewalk pavers are each, functionally, a different climate, and the plant list has to be built for the site rather than the map.