That happened to me on my first grow, it turned out I had my light too high above the seedlings. For flouresent light I believe they recomend 1.5 to 2 inches.
RoboGro Reviewed by RoboGro on . Long stem in first 5 days? The stalk on my seedling is about 3 inches high...Good or bad...It is holding itself up. But it just looks out of place around the three others that aren't even an inch yet.. I planted all of them about 1/8 of an inch into the soil. Rating: 5