Garden Calendar

* The Spring Orchid Fair with flowers on display and for sale, Saturday, 10 a.m.-3 p.m., at UC Irvine Arboretum, Campus Drive and Jamboree Road, Irvine, (949) 824-5833. $1.

* How to plant and maintain slopes on Saturday, 10 a.m.-noon, at the Arboretum of Los Angeles County, 301 N. Baldwin Ave., Arcadia, (626) 821-3222. $15, reservations required.

* “Twiggy Trellises,” a demonstration on making decorative garden supports, Saturday, 10 a.m., at Descanso Gardens, 1418 Descanso Drive, La Canada Flintridge, (818) 952-4401; https://www.descanso.com. $18.

* A talk on spring-blooming oxalis, Saturday, 9:30 a.m., at Sherman Gardens, 2647 E. Coast Highway, Corona del Mar, (949) 673-2261.Free.

* Japanese Garden Study Seminar, with lectures and workshops, Saturday and Sunday, at the Japanese Friendship Garden in Balboa Park, San Diego, (619) 232-2721. $225, call for reservations or register on the Web site, https://www.niwa.org.