More info for the terms: capsule, charate, duff, root crown, top-kill
Deer brush reproduces from seed and by sprouting from the root crown and/or stem [22]. It occasionally layers where branches contact soil [14].
Seed reproduction: Deer brush first produces seed at about 4 years of age [21]. Ripe seed is forcibly ejected from the capsule when the capsule dries and splits [64]. Deer brush is a seed banking species. Seed is stored in extremely high densities in duff and the upper few centimeters of mineral soil. Anderson [4] estimated that the deer brush seed population in a mixed coniferous forest in northern California was greater than 2 million seeds per hectare. Viability of the seed averaged 90.6 percent in the laboratory [4]. Similarly, Kauffman and Martin [37,38] reported a range of 60 to 90 percent viability of deer brush seed from three northern California mixed-conifer forests. Viability of deer brush seed is generally high, and the seed is long-lived. Quick and Quick [62] reported 90 percent viability of 24-year-old seed. Other researchers have suggested that deer brush seed remains viable for well over 100 years [4,22,62].
Seed is dormant until the hard seedcoat is scarified by fire or mechanical disturbance such as logging [19,22]. Optimal temperatures for scarification range from 170 to 195 degrees Fahrenheit (77-90 deg C) [39]. High-consumptive fire (> 90% of duff burned) kills most seed in duff, but most seed in mineral soil survives. Anderson [4] found that following one high-consumptive fire, 12.5 percent of seed in duff and 52.4 percent of seed in mineral soil was viable. Seed requires stratification follow scarification, and usually germinates in spring [39]. Keeley [41] reported that light inhibited germination, an unusual response, and that charate (charred wood powder) had no effect on germination.
Best establishment occurs with seed in bare mineral soil [7,22]. In a greenhouse study, seeds planted at one-half inch (1 cm) when in shade and at 1 inch (2.5 cm) when in sun showed better seedling emergence than seeds planted at greater or lesser depths. Emergence did not occur with seeds planted on the soil surface [1]. Nearly all seedling establishment occurs in the first postfire spring; establishment after the second postfire year is rare [22]. Plants typically average 3 to 4 inches (8-18 cm) in height at the end of their first growing season and 8 inches (20 cm) in height at the end of the second growing season [21,22,77].
Vegetative reproduction: Sprouts grow more rapidly than seedlings, reaching a height of 30 or more inches (76 cm) in their first year [22]. Age at which deer brush sprouts first produce seed is undocumented; however, sprouts of most Ceanothus species produce seed after 3 to 6 years [21]. When deer brush plants are top-killed before they become decadent, roots remain alive, and root crowns retain the ability to sprout for years beyond the 35-year life expectancy of other stem tissue. Without periodic top-kill, root systems and root crowns of decadent plants die [22].