Spring blossoms pop from late February through the first weeks of June. Some spring blooms, like the shrubby lilac, have to mature for several years before blooming, while others, like the eager crocus, spring from bulbs that hold all the nourishment they should bloom. Although some planting times may vary for several species, planting time for spring blooms typically depends on whether you are planting seeds, grasses, plants or bulbs.

Seeds

Ripened seeds in existing plants like Calendula (Calendula officinalis) or California Poppy (Eschscholzia californica), are planted once the seed pods ripen in summer. Other spring annuals, such as Johnny jump-ups, or pansies (Viola tricolor, V. cornuta), may re-seed themselves throughout late summer and fall. If you’d rather not trust Mother Nature, sow seeds in store-bought packets of Columbine (Aquilegia spp,), sweet William (Dianthus barbatus) and additional mid-to-late spring bloomers in autumn after the first rains begin into early winter. Native wildflowers’ cycles might vary according to local climate events like fire season or drop drought and wind, so check with the local university extension’s Master Gardener program or a chapter in the nation’s native plant society for advice about California’s native plants like Siberian spring beauty (Claytonia sibirica), tickseed (Coreopsis spp.) or tufted poppy (Eschscholzia caespitos).

Divisions

Perennials like daylilies (Hemerocallis spp.) , yarrow (Achillea millefolium) and bee balm (Monarda spp.) Or natives such as Columbian windflower (Anemone deltoidea) and scarlet larkspur (Delphinium cardinale) develop from thick clumps that could be divided to create new plants. For the best spring bloom, these divisions should happen in mid to late autumn. New plants need four to six weeks to establish roots before cold weather enforces dormancy. In warmer U.S, Department of Agriculture plant hardiness zones 8 through 10, this means that lots of spring-flowering plants may be divided successfully through December.

Bulbs

Flowers such as California’s native Humboldt lily (Lilium humboldtii) and other garden lilies grow from bulbs. True bulbs have narrow necks in their tops and increase plates on rounded bases. Iris, including California natives Douglas (Iris douglasiana) and Del Norte Country iris (Iris innominata) grow from rhizomes, but are treated as bulbs. Daffodils (nartcissus spp.) and alliums (Alliums spp.) , including mountain onion (A. unifolium), all of develop from true bulbs. Mariposa lilies (Calochortus luteus and C. monophyllus) also create bulbs but develop best when opened from bulblets or seed. In USDA zones 8 through 10, bulbs and rhizomes are best planted from late autumn through early December. Divided bulbs, rhizomes and bulblets should be re-set instantly when raised in late summer or early autumn.

Seedling and Bare Root Plants

Local nurseries and mail order growers do a lot of the work of growing crops from seed or maturing bulbs for gardeners. They will release plants available in — or a few weeks before — optimum planting time in spring or fall. Nursery packs of spring-flowering annuals and perennials or bare root plants must be planted immediately upon receipt, providing the danger of frost is past. Local growers and reputable mail order nurseries supply putting instructions and hardiness info on plant tags or invoices.

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