As we hope for winter rains as nourishing as last year’s, now is the time to prepare perennial garden space. Many vegetable farms and gardens operate on a seasonal cycle of annual plants whose short lives span the longer, warmer days of spring to fall. In contrast, perennial plants have life spans ranging from several years to several decades (or even centuries, in the case of many trees) and provide a host of opportunities for year-round food and forage for the human and other-than-human world alike.
Perennials are integral to the design of any garden, and growing long-lived plants is a deep investment in the time and space of your garden. Taking many years to mature, perennials provide diversity of structure, food and shelter throughout the winter months when annuals have reached the end of their lives. Perennials are the shapes and forms a garden is designed around, since they persist through the years. They are the engineers of soil biology, building healthy garden soil over time thanks to the natural processes of leaf drop, fungal partnerships in long-lived root systems, and the pulses of water and microorganisms that plant growth creates.
Even a small space can grow a dense garden that provides a living landscape year-round. As human-caused climate change and habitat destruction continue to threaten many precious and unique plant, animal, bird and insect species, we can help counter these losses with urban habitat as refuges of food, water, and shelter.
In coastal Southern California, late fall and early winter are the best time to plant perennials while soil is soft and workable from winter rains and plants have a cool, wet period of acclimation before the heat of the next summer. The choices of perennial plantings are almost endless: “low chill” fruit trees for year-round food production, California native plants for food and nesting materials for the many native insects and birds that make coastal California so vibrantly diverse and other edible and medicinal plants that grow vigorously in our mild climate.
California native plants are very desirable in a long-lived garden plan. They are the most low-maintenance plants, growing happily in poor soil without supplemental watering. In fact, for many native plants the greatest danger is soil that is too rich or too consistently watered. Most natives prefer well-drained soil and the seasonal watering to which they are accustomed, including more than six months without water. However, if you wish to keep natives showy and abundantly flowering through the summer, just provide low-drip irrigation to thoroughly soak the soil every month or so. For a list of some of my favorite native plants for the home garden, see my previous article from October 2018 on coastalview.com.
For all other perennials, including fruit trees and non-native species, it is especially important to take the time to build healthy, living soil capable of sustaining plant growth for many years. The most important step is to add high-quality compost to your soil. If you do not have the time and space to create your own, choose to support local producers of living compost. While there are organic options now available in garden stores, many are sterilized with high heat processes that cook all the microorganisms responsible for soil health. Instead, go to a local farmers market and find the person selling homegrown worm compost, or look for “living” varieties at the store.
Even a small amount of compost can make a huge difference in a plant’s vigor and success, although more is always best. In general, I apply three to four inches of compost to the top layer of soil, turning it into the soil with a shovel or spading fork. Once soil has been gently soaked, it is time to transplant. Make sure plants are firmly pressed into the ground—root to soil contact is one of the primary triggers to growth, so don’t feel shy to step or tamp around a plant’s base.
Another important step for a perennial garden is a thick layer of organic mulch such as leaf litter, wood chips, or straw. Mulch serves to protect soil from the harsh effects of the sun and conserves water. There is often free mulch in front of City Hall on Carpinteria Avenue for small-scale pick-up. In addition, Santa Barbara County offers unlimited free mulch if you pick up at the transfer station, or will deliver for a small fee. See lessismore.org for details. And most importantly, let fallen leaves lie—they are free compost and mulch in a perennial garden, as well as important habitat for many over-wintering insects such as one of our showiest native pollinators, the day-flying sphinx moth.
Growing a garden of long-lived plants is a choice which holds a lot of hope. Dense, perennial gardens are wishes for a long and healthy garden life, as well as a gift to the many creatures which call our community home.