University of California, Riverside

UCR Botanic Gardens

The Physical Site

alder trees

The Physical Site

The UCR Botanic Gardens occupies 16 hectares (40 acres) of rugged, hilly terrain along the eastern boundary of the U.C. Riverside campus, in the foothills of the Box Springs Mountains. Natural features include two prominent arroyos with steep slopes and intermittent water flow in one - Chancellor's Canyon - and a spectacular assemblage of huge, weathered granite boulders in the upper reaches of the other - Alder Canyon. The elevation varies from 335 meters above sea level at the entrance to 442 meters in the southeast corner of the Gardens (1100 to 1450 feet).

The annual rainfall in this area has averaged only 271 mm (10.67 inches) over a 97-year period. From 1956 to 1986 the rainfall exceeded the long term average only ten times. The majority of this scant rainfall falls between November and May. With such low rainfall, especially during the hottest time of the year, the Gardens needs to be under irrigation most of the year to grow any but the most drought tolerant plants.

view of the gardensFrom a horticultural perspective, the Gardens is in USDA Hardiness Zone 9 and Sunset Western Garden Book Climate Zone 19. The combination of this local subtropical climate and the irregular terrain produce a range of "microclimates" that allow a surprising variety of plants to be grown. The cold-air-drained upper elevations are nearly frost free, while the lower canyon bottoms are likely to receive light frosts in winter. The average maximum temperature for the year is 26 degrees C (78 degrees F) while the average minimum is 10 degrees C (50 degrees F). Over a 59 year period, Riverside averaged 14 days with a minimum below 0 degrees C (32 degrees F) per year. Over a 12 year period, the number of days with a maximum over 32 degrees C (90 degrees F) has been 59 per year.

About one-third of the Gardens' 40 acres remains unplanted. This land consists of variably degraded Riverside Coastal Sage Scrub Community and grassland. Common plants native to the site include brittlebush (Encelia farinosa), California buckwheat (Eriogonum fasciculatum), California sagebrush (Artemisia californica) and deerweed (Lotus scoparius).

Native Plants found at the UCR Botanic Gardens

Perennial Plants
Artemisia californica California sagebrush
Baccharis salicifolius Mule fat
Datura wrightii Jimson Weed
Dichelostemma pulchellum Blue dicks, wild hyacinth
Dudleya lanceolata Live forever
Encelia farinosa Brittlebush
Epilobium (Zauschneria) canum California fuchsia
Eriogonum elongatum Wild buckwheat
Eriogonum fasciculatum California buckwheat
Galium angustifolium Narrow-leaved bedstraw
Gutierrezia californica California matchweed
Haplopappus (Ericameria) palmeri     Palmer's goldenbush
Lessingia filaginifolia California-aster
Lotus scoparius Deerweed
Marah macrocarpus Wild cucumber
Melica imperfecta Melic grass
Mimulus longiflorus Monkeyflower
Mirabilis californica Wishbone bush
Nothalaena newberryi Cotton fern
Opuntia littoralis Prickly pear
Opuntia parryi (O. californica) Snake cholla, cane cholla
Phacelia ramosissima
Salvia mellifera Black sage
Sambucus mexicana Elderberry
Salvia apiana White sage
Sarcostemma cynanchoides Climbing milkweed
Scrophularia californica California figwort
Solanum xantii Purple nightshade
Annual Plants in Season
Amsinckia menziesii Fiddleneck, rancher's fireweed
Antirrhinum nuttallianum
Calandrinia ciliata Red maids
Camissonia bistorta California sun cup
Camissonia micrantha
Crassula connata Pygmy-weed
Cryptantha intermedia Popcorn flower
Eucrypta chrysanthemifolia
Gilia angelensis
Lasthenia glabrata Goldfields
Lotus strigosus
Lupinus truncatus Collar lupine
Nemophila menziesii Baby blue-eyes
Pectocarya penicillata
Phacelia distans
Phacelia minor Wild Canterbury bells
Salvia columbariae Chia
Tropidocarpum gracile

More Information

General Campus Information

University of California, Riverside
900 University Ave.
Riverside, CA 92521
Tel: (951) 827-1012

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Botanic Gardens Information

Botanic Gardens Schneider House Office
Botanic Gardens

Tel: (951) 784-6962

Mailing Address:
Botanic Gardens
University of California
Riverside, CA 92521-0124