We always grow a few varieties of basil in our garden and most are great when made into pesto. If you are planning on planting basil specifically for making pesto, we recommend using the classic Genovese Basil! Most grocery stores only carry sweet varieties and they will work perfectly. Exceptions: The flavors of Thai basil (which has a lime and coconut scent to it) or Holy Basil wich is bitter do not pair well with the ingredients in pesto so we do not recommend them. While they would taste okay opal basil or purple basil will make your pesto look unpleasant. We have tried lemon basil in pesto and it adds a distinctly lemony flavor which can be good in some simple applications (like on plain pasta) but is not for everyone so proceed with caution with lemon basil.