Order 2016 Almanac Now - Get 3 FREE Gifts
Assuming they were plantedAssuming they were planted correctly, you could use a high phosphorus fertilizer to encourage bloom. D not use a fertilizer containing nitrogen--it inhibits bloom, weak tubers, or rot.

2015 Special Edition Garden GuideCooking Fresh with The Old Farmer's AlmanacThe Almanac Monthly Digital MagazineWhat the heck is a Garden Hod?