The Horticultural Alliance of the Hamptons continues to offer intellectual sustenance for garden enthusiasts during the winter months with two programs this weekend. Saturday morning at 11, Carolyn Gemake will moderate a discussion of two books, Edward Hyams’s “Capability Brown and Humphrey Repton” and Doug Tallamy’s “Bringing Nature Home.” The talk, which is free and open to the public, will take place in the horticultural library on the ground floor of the Bridgehampton Community House.