Yeah the plants grow much slower if they are cold. I'm in georgia and they grow about that slow. Don't worry when summer gets here they wikll grow too fast... trust me. You may have planted too deep but if you did then they should be ok. Some may die but you got all year to start more. I currently have about 15 plants and they are all quite small (3-5"). I like to burry the bottom of the stem with soil to encourge it to become part of the taproot. I only keep the leaves above soil. Makes the stalk quite strudy.