In addition to selling seeds, compost, and garden tools to Brooklyn’s green-thumbed do-it-yourselfers, Hayseed’s Big City Farm Supply, the pop-up urban farming shop in Greenpoint that closes at the end of this month, also offers classes on a variety of topics related to cultivating plant life. This Sunday, Molly Culver of BK Farmyards will be teaching a class called Growing Flowers for Arrangements that sounds like a good bet for anyone who has a little bit of outdoor space and the desire for a flower garden. The 2-hour course covers the basics of growing “specialty cut flowers,” which are heirloom varieties that are a notch above your run-of-the-mill lilies, irises, and garden roses, as well arranging and bouquet making. The $40 signup fee includes a few packets of flower seeds so that, armed with your newly acquired expertise, you can plant and harvest your own flowers in 2013. While you’re there, check out the Perfect Nothing Catalog, an arty shop in a shack in the middle of Hayseed’s garden area where you can find items you don’t necessarily need, but will love.