Ask Mr. Smarty Plants

Since the seeds have a hard coat, scarification will aid in getting them to germinate. Jill Nokes in "How to Grow Native Plants of Texas and the Southwest" describes three variations of scarifying by soaking in concentrated sulfuric acid. For all three methods the seeds were soaked in the sulfuric acid for 30-45 minutes, then rinsed thoroughly and air dried on newspapers. The simplest method next covered the seeds with boiling water and left them in the cooling water overnight. The next day the seeds were planted in individual containers. Another method involved cold stratification at 41° F. for 30 days after the 30-minute scarification in sulfuric acid. The final method aerated the scarified seeds in water in glass jars. The water in the jars was changed when it became discolored. When seeds began to swell, they were removed and stored in plastic bags with moist perlite for 60 days in cold storage. Seeds began to sprout by the end of that period and were planted in individual containers. Please note that caution should be used when handling concentrated sulfuric acid. it can cause skin burns and severe irritation of the respiratory tract. Ideally, it should be used only under a vented hood.

Another method for scarification of the seeds is abrasion using sand paper or sand. The seeds can be rubbed over fine sand paper to abrade the seed coat and then covered in boiling water and allowed to soak overnight in the cooling water before planting. Another method involves making a slurry of water and fine sand in a glass jar, adding the seeds and shaking vigorously before the boiling water treatment and overnight soaking in the cooling water.