Sphagnum peatlands are threatened at a global scale, not only by peat extraction, but also by Sphagnum harvesting. In Chile, dry Sphagnum moss is mainly exported for use as substrate for horticulture and orchids. Although the use of Sphagnum within Chile is limited, there are no data about its productivity and growth. These peatlands have a special microtopography with hummocks, hollows and lawns, which vary the distance of moss to the water table level. In these ecosystems, the water table is almost all year near the surface. We measured cumulative and relative growth rates and productivity during approximately one annual cycle in private Sphagnum peatlands that are being yearly harvested for commercial purposes. We evaluated the relationship between Sphagnum magellanicum growth and productivity with microtopography and water table depth. Productivity, cumulative and relative growths were higher in lawns than in hummocks. Overall and relative growth of S. magellanicum showed a negative relationship with depth of the water table. There were also differences between sites, some of them showed high growth rates, but low productivity. Sphagnum extraction in Chile, is now at low scale, but the growing international market demands constitute a real threat to the resource.