The honest answer to “should I seal it?” — plus cleaning, stains, joints, and the annual care calendar.
Bluestone's maintenance reputation is the best in the natural-stone world — and most of what owners are sold beyond soap and water is unnecessary. Here's the honest manual.
Most New England bluestone does not need sealing. The stone's density and low absorption are the protection; unsealed bluestone has floored the region's estates for a century. Sealing earns its cost in three specific cases: outdoor dining zones where oil and wine meet stone weekly (a penetrating, natural-finish impregnator adds stain-response time), full-color stone in formal settings where owners want the wet-look “enhanced” tone (an aesthetic choice, honestly labeled), and salt-heavy exposures like the splash edge of salt-system pools (pool guide). If you seal: penetrating/impregnating sealers only, never film-forming topcoats — films trap moisture beneath the surface, and trapped moisture plus frost is precisely the damage sealing pretends to prevent. Expect 3–5 year reapplication cycles.
The regimen: sweep, rinse, occasionally wash with a pH-neutral stone soap or mild dish soap. A soft-bristle push broom handles pollen film and traffic grime. Pressure washing: fine at fan-tip, sub-2000 PSI, sensible distance — annually at most; aggressive close-nozzle work erodes joints and can etch cleft faces. Never: acid cleaners (muriatic etches bluestone's calcite content), wire brushes, or bleach on planted joints.
Polymeric sand joints want inspection each spring — top up washouts, and expect a full refresh every 4–7 years. Stone-dust joints get an annual sweep-in of fresh dust. Planted joints get weeded and re-plugged like any garden. Mortared joints on wet-set work want cracked sections repointed promptly — winter finds every open crack (the freeze-thaw guide explains the stakes).
Spring: wash the winter film, inspect joints, top up sand, note any heave for the mason while it's fresh. Summer: nothing but enjoyment and a rinse after big cookouts. Fall: keep leaves moving — the tannin season; final joint check before frost. Winter: plastic shovels, and the salt discipline covered in the winter guide. That's the whole job — roughly two honest hours a year for a floor that outlasts its owner.