The Central Square space soon to be emptied by the Harvest Co-op grocery store and attached Clear Conscience Cafe could become another grocery store. (Photo: Elisha Marshal)

The Central Square space soon to be emptied by the Harvest Co-op grocery store will probably become another grocery store, said owner Morris Naggar of 3MJ Realty.

Harvest, which has been there for two decades, and the attached Clear Conscience Cafe said Friday that the rising costs of leasing the space are pushing them out. A lease extension from Naggar allows the businesses to stay through Aug. 1. While cafe owner Daniel Goldstein has no concrete plans for his business starting in September, a spokesman for the grocer said Harvest will move across the street to a space a little more than half its current size.

Naggar said he is already in discussions for a new tenant.

“We would like to continue to find an appropriate food use for the space. The way it’s laid out is conducive to that,” he said Friday of the 581 Massachusetts Ave. site. But he hoped a new grocer would “not be in any kind of direct competition with Harvest,” but would complement the 4,000-member co-operative.

There are also two full-service grocery stores about one-third of a mile away: a Shaw’s/Star Market at 20 Sidney St. and a Whole Foods at 115 Prospect St.

Naggar’s company is marketing the Massachusetts Avenue space as 18,000 square feet by combining the space used by Harvest and the Clear Conscience Cafe and adding as much as 4,000 square feet once used by Pearl Art & Craft Supplies until it closed in late January 2010. More recently it was used as a popup store for the PlayStation Vita and, in March, as a base for the Together electronic music festival. Some former Pearl space became a Vim Fitness Spa and Salon in February — a two-year  gap between uses.

“I don’t think it will take as long, but it takes time to replace that much space,” Naggar said of the  18,000 square feet.

Assuming there’s a tenant committed Sept. 1, he estimated six months of renovation that could bring a large grocery store to Central in late winter or early spring.

It would be up to the new tenants to decide whether the parking would be offered for use to a farmers market or agricultural drop-off point, as Harvest allows.