Medicinal Gardening: Annual vs Perennial Plants

One of the main components of a medicinal food garden, as well as optimal nutrition, is perennial plants.  Annual plants, such as tomatoes, zucchini and lettuce, are the typical garden plants, and they live out their lives in one season.  Usually they are started from seed in the spring, produce a mature plant in the summer, then flower and go to seed in late summer or fall.


In contrast, perennial plants either have “forgotten” how to produce seeds and just continue to grow year after year.  Or, more commonly, they produce seeds and fruit in late summer or fall, but this process doesn’t kill the plant.  There are countless examples of perennial plants — trees, shrubs, herbs and many, many others. 


Perennial plants usually have deeper root systems than annual plants, which allow them to anchor themselves against wind and rain as they get bigger.   These larger root systems allow the plants to “forage” the soil for needed nutrients more vigorously than annual plants.  In addition, because they are longer lived, perennial plants need to develop a defense system that typically is not needed by garden annuals.  Such defense systems include thick bark to ward off mammals and insects, as well as thorns.   More relevant for us, perennial plants typically develop a rich variety and robust amounts of certain phytochemicals (meaning plant-produced substances), which provide chemical defense and support for the plant’s immune system and ability to heal from infestation, disease or wounds.   It is one of my primary theses that these same phytochemicals support our own chemical defense and immune systems.  Phytochemicals have been extensively studied and have been shown to prevent and treat human disease.


In our garden in Napa, we grow many perennial vegetables. Some well-known examples include asparagus, artichokes, rhubarb, sorrel and dandelion. Less common varieties include tree collards and perennial kale.  Typically, the taste of perennial vegetables is stronger than common annual vegetables, probably because of their lower carbohydrate levels and higher phytonutrient levels. In future blogs, I will get more detailed about how to find, grow, and process these valuable additions to your diet. 


To encourage adding perennial plants to your regular diet, we offer three unusual perennial plants at Dr. Cowan’s Garden.  Cholla buds are the flowering tips of a perennial cactus grown in the Sonoran desert.  Chaga is a medicinal mushroom with great healing powers for a variety of health conditions; it is wild-harvested from the Northeast U.S. and Quebec.  The chaga nuggets are brewed into a tea that has been valued as a health tonic across many cultures.  Finally, we offer Horseradish Powder, made from horseradish grown from a farm near Mt. Shasta, CA.  Horseradish is a perennial member of the brassicas family (which includes broccoli, cabbage and cauliflower) that, because of its sulfur-containing phytonutrients, is also a powerhouse in disease prevention. 


I heartily encourage everyone to begin today to add the rich variety of perennial plant products into your diet.


Tom Cowan, M.D.

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