Every year I look forward to seeing the blooms of the Humboldt lily (Lilium humboldtii) in June. The bold, orange spotted flowers sway on impossibly tall stems, brightening shady spots. They can be seen in the wilds of our local mountains (probably not this year after the fires, though there should be some nice wildflowers), or on the grounds and in the nursery at Rancho Santa Ana Botanic Garden. During the spring I watch as the tall stems emerge and shoot up, revisiting the plants until the showy flowers finally appear.
The Humboldt lily is one of many native geophytes that do well in Southern California gardens. Geophytes are plants that store carbohydrates underground in bulbs, tubers, corms, rhizomes or tuberous roots. They are similar to annuals in that most are present for a relatively brief period, and they do not tolerate wet soils during the heat of the summer. Because bulbs are fleeting contributors to the garden, they are best used as highlights or accents that will not be missed when their season is over.
Native bulbs that become established in the garden are long-lived, reliable plants. Dichelostemma, Triteleia, and Brodiaea will naturalize and spread slowly over time. When patches become too large or dense, they can be dug up in the summer for use in other parts of the garden.
Fall is the time to decide which bulbs you will add to your garden. They should be planted when the weather cools, in October or November. Plant them at a depth of approximately three times the length or width of the bulb, whichever is greater. Water the bulbs after you plant them and then wait for the rain. If the winter is dry, water, especially after the first leaves emerge, and continue while they are actively growing. After they bloom and the leaves die back, cut out the water. Watering during dormancy will rot the bulbs.
For some, it is difficult to use bulbs in the garden. They will not tolerate summer water, can be shaded out by more established neighboring plants, and are often sought after by gophers and other mammals who enjoy their rich succulence. Yet they make wonderful container plants. It is generally best to plant groups of bulbs in pots that are at least eight inches deep. Use a sandy soil mix: 40% potting soil, 40% sand, 20% loam. Once the leaves emerge, allow the surface of the soil to dry between watering. Fertilize your container bulbs with a mild liquid fertilizer during active growth. Re-pot the bulbs with fresh soil every third year or so.
A few years ago I received a gift of an adorable little bulb called cat’s ears mariposa lily (Calochortus tolmiei). The small, delicate, pink flower is lined with soft hairs, as implied by its common name. Sitting in a four inch pot on my back porch, I enjoy the plant as several flowers bloom over a period of a few weeks in April. After the plant dies back I set the pot in a protected spot near the house. Just as I look forward to the reappearance of the dramatic Humboldt lily, I anxiously await the spring to see if my diminutive cat’s ear will magically return again.