An easy way to ensure the pencil or pen goes down far enough is to put it next to a ruler. Cold temperatures, on the other hand, can freeze a seedling s cells and affect its ability to transport and use nutrients, water, and oxygen. In general, photoperiod-dependent plants produce higher yields and a higher cannabinoid index.  Source: <a href=http://www.lasuitehairdresser.it/cannabis-garden-alchemy-the-art-of-seed-buying-and-growing/>http://www.lasuitehairdresser.it/cannabis-garden-alchemy-the-art-of-seed-buying-and-growing/</a>