Woodsorrel, the shamrock-like plant in the foreground pictured in December, is a perennial herb that is not native to California. Some people like its yellow flowers in the spring, but it can be invasive. (Photos: Jeannette Warnert)

Tasks

• Control cool-season weeds before they mature and go to seed.
• Plants planted last spring and fall may need water if rainfall has been inadequate.
• Run sprinklers periodically through their cycles to maintain clean lines and to exercise the valves.

Pruning

• When harvesting blooms for arrangements, make cuts with an eye toward shaping the plant.
• Prune and shape dormant deciduous plants – shrubs and perennials.
• Cut away 50% of last year's growth on peaches and nectarines.
• Remove leaves from roses in January to force the plant into dormancy. This is not necessary with shrub or groundcover roses.

Fertilizing

• Apply nitrogen fertilizer to citrus trees prior to bloom.
• Always read labels carefully before applying fertilizer. Use only if necessary.

To control a nutsedge infestation, pull out the plants by hand, ensuring that the tubers on the roots are removed.

• Bare root planting season continues.
• Peas (both edible and decorative varieties) can be planted this month.  Before planting, soak dried peas between damp paper towels in a shallow dish. Cover loosely with plastic and keep towels moist.  Plant seeds when they're just beginning to sprout.

Enjoy now

• Annuals and perennials: Primrose (Primula polyantha), English primrose (Primula vulgaris), pansy (Viola), sweet violet (Viola odorata), Poinsettia (Euphorbia pulcherrima).
• Bulbs, corms, tubers: squill (Scilla bifolia), ‘Paper White' narcissus (Tazetta daffodils).
• Trees, shrubs, vines: Anthony Waterer spirea (Spiraea japonica), bridal wreath spirea (Spiraea prunifolia).
• Fruits and vegetables: lemons, navel orange, parsley.

Things to ponder

• Frost is possible when it is clear enough to see the stars.  Remember to leave frost-damaged foliage until danger of frost has passed. Prune later if needed.
• Remove fallen camellia blooms promptly to prevent petal blight on next year's flowers.

After decidious trees have lost their leaves, mistletoe is easy to spot. To control, remove the branch at its point of origin and at least one foot below the mistletoe cluster. (Photo: UC IPM)

• Remove fallen camellia blossoms promptly to prevent petal blight on next year's flowers
• Mistletoe is very difficult to control because reinfestation occurs from nearby infected trees. An infected branch must be removed at its points of origin and at least one foot below the cluster.

Pruning

• Wait to prune spring?flowering plants until after bloom - deciduous magnolias, spiraea, azaleas, and camellias
• Do not apply any treatments to pruning cuts or other wounds, because these materials are ineffective and often detrimental to plant health

Fertilizing

• No fertilization is recommended this month

Planting

• Bare root plants started now, while they are dormant, will have the full advantage of the spring growing season and will be well established during the coming year
• Bulbs, corms, tubers: cyclamen, dahlia
• Fruits and vegetables: bare root cane berries, garlic, leek

Enjoy now

• Annuals and perennials: dianthus, poinsettia (Euphorbia pulcherrima), toadflax (Linaria maroccana), stock (Matthiola)
• Bulbs, corms, tubers: snowdrop (Galanthus), narcissus
• Trees, shrubs, vines: camellia, Hawthorne (Crataegus)
• Fruits and vegetables: avocado, grapefruit, kumquat, pomegranate

Things to ponder

• Look through garden books for landscaping ideas using drought-tolerant or water-wise plants
• Avoid overhead watering if frost is expected

Pick up fallen camellia blossoms promptly to prevent petal blight on next year's flowers. (Photo: Wikimedia Commons)

December is the time to begin enjoying your home-grown citrus. (Photo: USDA)

Tasks

• Apply pre-emergent herbicide to lawns and beds later this month
• Deep-water trees and native plants if rainfall has been light

Pruning

• This is the time to work on dormant, deciduous plants - shrubs, vines, grapes, and roses, plus fruit and nut trees
• Crepe myrtles and redbuds may be pruned now
• Cut back and divide perennials

Fertilizing

• No fertilization is recommended this month
• When you do fertilize, always read labels carefully before application. Consult a plant expert at a nursery or a Master Gardener if you have questions

Planting

• This is the beginning of bare-root planting season. It is difficult to visualize the potential of bare-root plants, but they usually come with pictures to give you an idea
• Bulbs, corms, tubers: canna and crocosmia
• Fruits and vegetables: asparagus, cabbage, and bare-root berries
• Trees, shrubs, vines: azalea and camellia

Enjoy now

• Annuals and perennials: snapdragon (Antirrhinum), calendula, and Chrysanthemum Paludosum, Holiday cactus (Schlumbergera)
• Bulbs, corms, tubers: crocus and cyclamen
• Fruits and vegetables: beets, bok choy, chives, and mandarin oranges

Things to ponder

• This is a good time to look through seed catalogs
• Wood ashes are not beneficial in the garden as they increase soil alkalinity

Plant Iceland poppy transplants now for stand-out spring flowers. (Photo: Pxhere)

Tasks

• Monitor rainfall and adjust automatic sprinklers accordingly.  If rainfall is adequate, warm-season grasses require no supplemental irrigation
• Spray stone-fruit, apple, pear, nut, and flowering trees, and roses with dormant oil spray
• Now that the soil is cool and damp, sow seeds of spring wildflowers such as California poppy, clarkia and cornflower

Pruning

• Remove leaves from roses to force them into dormancy in preparation for pruning next month
• Prune out fire blight infections.  Cut the infected shoot or branch at its point of origin

Fertilizing

• Fertilize cool-season annuals, perennials and vegetables with a light, high-nitrogen or organic fertilizer

Planting

• This is not a big planting month unless you have purchased plants or bulbs and have not yet planted them
• Fruits and vegetables: radishes, spinach, plant from seed
• Annuals: forget-me-not (Myosotis), Iceland poppy (Papaver nudicaule), fairy primrose (Primula malacoides)

Enjoy now

• Annuals and perennials: stock (Matthiola), Iceland poppy (Papaver nudicaule)
• Bulbs, corms, tubers: paperwhite (Narcissus)
• Trees, shrubs, vines: heavenly bamboo (Nandina) Maidenhair tree (Ginkgo biloba)
• Fruits and vegetables: persimmons, potatoes, Savoy cabbage, snow peas

Things to ponder

• Be alert for frost warnings and cover tender plants when freezing temperatures are expected. Apply a layer of mulch to protect roots of vulnerable plants
• Amaryllis bulbs will bloom indoors and may do well planted outside with some shade and rich, well-drained soil

Source: Adapted from A Gardener's Companion for the Central San Joaquin Valley, 3rd edition, currently available from Fresno County Master Gardeners for $30. These can be purchased at our demonstration garden - Garden of the Sun (1750 N. Winery (McKinley/Winery), open Mondays, Wednesdays, and Fridays from 9 am to noon, and via email at mgfresno@ucdavis.edu. Gardening questions answered as well at mgfresno@ucdavis.edu.