Food shed planet tells us that growing basil is much more economical than buying it in the store.
They did the figures and came up with the price of basil from the store being about $16.00 per pound. At that price I would have to agree it would be way way cheaper to grow your own. If you like pesto you can go through a whole lot of basil.
They also tell how they make their pesto and then freeze it in ice cube trays. That makes a lot of sense, if you grow your own and freeze it in the summer you will have your pesto all winter and never have to buy the expensive jars or the pricey fresh basil again.
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Assortment of 12 Culinary Herb Garden Seeds: Parsley, Thyme, Cilantro, Basil, Dill, Oregano, Marjoram & More