Common camas can be propagated from seeds or bulbs. Common camas generally prefers full sun to partial shade, with bulb depth ranging from 2-8 inches (most commonly 4-6 inches deep). The bulbs of common camas can be substantially smaller in size and occur at more shallow soil depths than great camas. Bulb depth appears limited by shallow water tables, anoxic conditions, or restrictive layers. The occasional occurrence of a large, thick root beneath a bulb may aid in re-locating or re-establishing it at a greater depth. Plants require irrigation or moist soil conditions to become established, and camas can be difficult to establish in California.
Live Plant (Bulb) Collections
Common camas is readily established by transplanting wild or commercially grown bulbs. Wild harvests should be restricted to salvage sites with appropriate approvals or permits. Due to loss of wetland habitat throughout the United States, harvesting plants from the wild is rarely appropriate or legal except under salvage situations. Use of bulbs or seeds from local nurseries or greenhouses is strongly recommended.
The best time to excavate bulbs is from early summer through mid-fall. This is the “quiescent” period that follows seed maturation, foliar senescence, and development of the daughter bulb. However, commercial bulb harvest takes place when the leaves are still green and must be done carefully to avoid damage. The bulb tunic or covering is very thin (De Hertogh and Le Nard 1993). Given that camas commonly occupies sites high in silt and clay that dry out in summer, windows for digging are often narrow. There is a brief period when soils are moist after flowering in the spring; the next time to harvest is in the fall after the rains begin. Store the bulbs in a dry, dark, cool, well ventilated place in a potting medium such as dry peat moss, similar to recommendations for fall planted/spring flowering bulbs (such as daffodils and tulips). Keep the bulbs from completely drying out and transport or store at 63-68° F (De Hertogh, Noone and Lutman 1990). Common camas reproduces vegetatively by offset bulblets (De Hertogh et. al. 1993). However, much less than one percent of a wild population may produce offsets and bulbs may be stimulated to do so only as the result of a wound (Thoms 1989).
Plant camas outdoors in the fall or early winter, when soils are moist enough to dig and prevailing soil temperatures are cool. This is generally below 60°F. Fall planting allows for better root development and fulfillment of any chilling requirement for flowering (De Hertogh et. al. 1993). Bulbs, bulblets, and offsets can be utilized. However, if flowering is desired the following spring, bulbs must be of sufficient age (3-5 years old with 3-4 bulb leaves or scales) and size (Thoms 1989). Bulb leaves are laminate concentric layers that comprise much of the bulb, reminiscent of an onion. Bulbs with just two bulb leaves never flower, those with three routinely flower, and those with four almost always flower. Older bulbs will be found deeper in the ground, and bulbs which flower will probably be at least 0.6-0.8 inch (1.5-2.0 cm) wide (Thoms 1989). In the commercial bulb trade, the minimum size for export and thus flowering is a circumference of 2.4 inches (6 cm) (De Hertogh and Le Nard 1993). This is roughly equivalent to a diameter of 0.75 inch and about one-half the diameter and circumference of great camas.
The larger the bulb, the greater the planting depth can be. Planting depth ranges from 0.5-1 inches for 1-2 year old bulblets up to 4-6 inches for mature bulbs (as measured to their base). Larger bulbs (1.5 inches in diameter or greater) can be planted deeper (8-10 inches) if drainage is appropriate. Commercial production involves planting from October to November in well drained soil of pH 6-7 with at least 2% organic matter, covering with at least 3 inches of soil above the bulb “nose”, applying 2 inches of straw mulch, fertilizing with 7-14-28 fertilizer four weeks after planting, and harvesting in July (De Hertogh, Noone and Lutman 1990). Keep the camas bed damp until it gets warm. Once plants senesce after flowering, stop watering so seeds form and bulbs cure. Suggested spacing for flower beds and naturalized landscapes vary from 3-4 inches apart (8-10 per sq. ft.) to 6-8 inches apart. Other publications recommend 6-8 bulbs every 12 inches for outdoor gardens. A dense “natural” stand may have 9 plants/sq. ft. (100/sq. meter) or more (Thoms 1989). It may be necessary to bury bulbs with a protective wire mesh to prevent herbivory. The mesh needs to be coarse enough to allow shoots to grow through (De Hertogh et. al. 1993).
Seed Collections
Common camas propagates easily from seed. It can be collected as soon as the pods mature (turn light brown) or split open to reveal the mature black seeds. Pods ripen from late May- July depending on latitude, longitude, moisture conditions, or elevation. Dry seeds can be stored frozen or in a cool, dry place prior to planting.
Camas seed requires 42-100 days of cold temperatures (34-40°F) under moist stratification for maximum germination (90-100%)(Emery 1988, Guerrant and Raven 1995, Deno 1993, Northway pers. comm. 1998, Thoms 1989). “Moist stratification” means placement of seeds which are “imbibed”, or have soaked up water, in layers of a moist medium at cool temperatures to allow for after-ripening. Germination also requires cool conditions and can occur in the dark (Northway pers. comm. 1998). The alternative is to plant seed outdoors in the fall (Sept-Oct). One-leafed, grass-like seedlings will emerge in February or March under suitable conditions. Seedlings require moisture through the spring growing period to survive. Warm temperatures during seedling development can be lethal.
Suggested site preparation methods and seeding rates for wetland revegetation are not well known, but a broadcast rate of 20 live seeds/sq. ft. for both Camassia sub-species resulted in poor to good seedling counts the following spring (0-10 or more seedlings/sq. ft.) (Darris, pers. comm., 1999). Seedling success was dependent on weed competition, hydrology, type of disturbance, mulch, erosion, or other factors. Camas seedlings were inhibited by dense stands of live grass such as Lolium multiflorum. However, seedlings appeared to benefit when grown in the mulch of native grass (Deschampsia cespitosa), at least on well-drained, stable, slightly higher ground (Ibid). In areas with wet, mild winters, soil scarification for shallow seed coverage or just constant moisture from irrigation or winter rains can result in good germination. At least one grower sows seed directly on the soil surface in the fall (Robinson pers. comm. 1999). However, other growers have found that a 1-2 inch covering of organic mulch is required during the first growing season to protect the tiny bulblet from exposure to dry soil, surface cracking, and extreme temperatures. Sawdust or a chemically killed dense stand of grass works well (Watson pers. comm. 1999). Seeds deeper than 0.4-0.8 inch (1-2 cm) will not germinate successfully (Watson 1988).
Seeds per pound: Camassia quamash ssp. breviflora – 131,000 (+/- 20,000)