Sonoma County winter gardening tips: Turning one plant into many

Though the days are still short, and nights hover overlong, the growing season is approaching. Outside, the tangle of wet and decaying vegetation beckons to our pruning shears.

Under the tangle of plant matter is new, fresh growth and possible jewels waiting for us - jewels in the form of volunteer seedlings and plant divisions we can make to create more plants for our gardens.

Scattering or repeating the same plant around your garden or flower border helps unify it in terms of color and form. At this point in the season, spent plant stems and stalks are mostly rotted and cutting them back and removing them is easy.

Spent daylily and alstroemeria leaves have likely turned to rotted mush, and the old, dead stems of plants like agastache, aster, Shasta daisies, sedum, centranthus, gaura, Verbena bonariensis, goldenrod, coreopsis, eryngium, penstemons, Helenium, catmint, California fuchsia, lady's mantle, yarrow, and other perennials are really unsightly.

Underneath the dead, old or senescent stems is fresh new growth waiting to be liberated. This should be easy to see now, and indicates on the plants where they should be cut. Remove this spent foliage to as low as you can just below the new growth.

Yarrow needs to be cut almost to the ground. In some plants like the larger penstemons, cut old stems down to just a couple of inches above the ground to allow new buds to push growth. Native penstemon species usually just need flower stalks and any growth that looks scruffy removed. A sharp pair of pruners makes these processes easy.

Once the flowerbed or garden is liberated from this mess, it will be easy to see and assess what is left. Some plants may have died, some have spread and others have seeded themselves.

This is the perfect time and point of growth to determine what plants didn't work for you there, and what you want more of. You may choose to remove some plants, and to move others to another place. Plants that really grew and flowered well may be candidates to use more of. Flowers like blanket flower (gaillardia), verbena and wallflowers are short-lived and many only last two or three years. If they don't look good, it may be time to remove them. Plants spread at different rates and some can take many years to achieve any mass, while others may transform in size in one season from a 4-inch pot to a three-foot square area of growth, giving an indication of what the future holds. Garden conditions often dictate the rate of growth, and good conditions foster faster growth. Too-rapid spreaders may be candidates for removal if yearly maintenance is not on your agenda.

In winter, after plants are cut back, the state of the garden is completely revealed and the weather conditions are usually wet and cool - perfect conditions to dig up and replant plants without causing transplant shock. It is the best time to dig up too dense seedlings and discard them, give them away or plant them in other places.

Flowers like gaura and the tall Verbena bonariensis often have an over-abundance of successful volunteer seedlings and can take over flowerbeds. You can avoid this situation by cutting the plant back really hard midseason as the growth begins to become overmature. They will grow back with fresh growth and bloom again. Other plants, like columbine, have a limited amount of seedlings. These are like jewels for the taking and are worth digging up and replanting. Make sure to get a clump of soil around the roots. Plant at the same soil level they were growing in. If rain is not in the forecast, water the plants in.

Plants that spread are easy to divide. There are a couple of methods to divide plants that spread. Some form separate plants or clumps that are super easy to dig up and plant in other places. Plants like Aster ericoides ‘Monte Cassino' develops a bald patch in the center of the plant after a few years. This growth pattern indicates the plant needs dividing. The outside ring of growth is very easily cut to into pieces with a shovel. From one plant you may get four or five. The original plant will greatly benefit. Other plants like some Eryngium or sea holly, slowly generate offshoots that are easy to individually dig up. Plants like catmint, chrysanthemums, California fuchsia, monarda, Coreopsis verticillata, oregano, Salvia gauranitica, Shasta daisies, some perennial sunflowers and asters and yarrow form spreading clumps that are easy to cut into pieces with a shovel. Plants like daylilies, heleniums, and redhot pokers and some asters form large clumps over time, but don't spread. They require more effort to cut up. All of these plants can then be replanted, potted up to plant later or given away.

As you cut some plants like penstemons back you may discover roots coming from stems where they have been in contact with the ground. Simply cut these stems off, remove spent flowers, and replant them.

Another method of dividing plants is to dig the plant up and the swish the rootball vigorously in a bucket of water until the soil has fallen off. Then you can more easily see it and decide how you are going to cut it up with pruning shears into a number of pieces to replant. These pieces should be repotted or replanted right away and watered so roots don't dry out. This is best done in winter unless you have a cool greenhouse or can otherwise keep the plants moist and out of direct sun.

Propagation is fun and rewarding! One plant can turn into many.

Kate Frey's column appears every other week in Sonoma Home. Contact Kate at: katebfrey@gmail.com, freygardens.com, Twitter @katebfrey, Instagram @americangardenschool