DEERFIELD TWP. — For four generations, Natorp’s Inc. has been in the business of growing.

Now the plant grower and retailer plans to convert a 128,000-square-foot greenhouse on Snider Road to a showroom that will bring customers a greater selection of locally grown plants.

Planned for a 190-acre site the business uses to cultivate more than 1 million plants it grows annually, the structure will transform the business from a garden store into a massive garden center, according to Kyle Natorp, the business’ president and CEO.

Plans for the business’ new concept were “greatly influenced” by its patrons, Natorp said.

“We’ve had this outlet sale in the fall here on the property for well over 10 years now and that’s been growing and growing,” he said. “We get incredible feedback from our customers and quite a few of them ask why we don’t do this in the spring.”

The new concept is slated to be open for both fall and spring planting seasons starting in the fall of 2012. When it opens, the store at 5373 Merten Drive will close, Natorp said.

“At any one time in our stores we just have a small snapshot of what we grow and carry,” he said. “For example, we grow 180 varieties of trees, but if you go to our store on Mason-Montgomery and Merten Drive, at any one time we might have 30 varieties. It doesn’t showcase what we really do.”

Even during the outlet sale, Natorp’s cannot put every variety on display because of space reasons, Natorp said.

The expansion will allow customers to see annuals, perennials, container and field-grown trees and shrubs being grown and cultivated prior to purchase, he said.

“With this new model we’ll be able to showcase that and the customers will have access to that inventory,” he said. “It gives us a lot more things that we can offer than we ever could at our stores because the store is just a limited space.”

In addition to having access to plants grown in the region’s own climate and soils, customers also will be able to pose plant questions to on-site horticulturalists.