the plants were about 40" tall so I cut the main stalk into short sections and I noticed the center of them looked like a straw. I realize that the water containing the plant's nutes moves thru it to deliver food to the entire plant but I thought it would be thru a fiberous like material, kind of a wick system, these were like a straw. A bb could pass thru. Is this normal or a sign of underwatering? Any info appreciated. thanks