Sequential planning focuses on geophytes

ON GARDENING

Moore’s Crinum (Crinum moorei). A fast winter growing plant that rises to 3-4 feet high with stout deep-rooted bulbous bases and long broad green semi-succulent leaves. In mid summer, it produces 4-inch-wide goblet-shaped light pink flowers held in umbels above the foliage, then enters a short summer dormancy and leaves die down. This plant is native to the forests of South Africa’s Eastern Cape.

Spider lily, Peruvian daffodil (Hymenocallis × festalis ‘Zwanenburg’). This plant is a hybrid of garden origin within the Amaryllis plant family (Amaryllidaceae). It develops a basal clump of linear, strap-shaped, 36-inch-long leaves, growing directly from the bulb. In late summer, a solid 30-inch-tall scape rises from the center of the foliage, topped by an umbel of two to five fragrant, white, spidery flowers. Each flower is 5 inches across, with six narrow perianth segments and a daffodil-like staminal center cup.

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The current period of dormancy provides gardeners with time planning for the future. In a recent column, we emphasized sequential planning, with the long-term goal of developing a landscape with a year-round schedule of attractive blossoms.

This planning includes selecting plants that bloom during each season, acquiring those plants through local garden centers or mail-order nurseries, and installing them early enough for them to establish roots and develop blossoms at the intended time.

Pursuing a year-round garden goal all at once would be a formidable project. A more practical approach would focus on plants for a specific season, and acquire and install them to prepare for the targeted bloom time.

A recent column addressed several categories of perennial plants that bloom in the spring. That column was published early enough for the gardener to find, acquire and install such plants.

The next column was about pruning existing roses, with notes about propagating these popular plants and adding new roses to the garden. That was a break from sequential planning because rose cultivation should be considered presently.

Today’s column returns to sequential planning and orients to geophytes: perennial plants with an underground food storage organ, such as a bulb, tuber, corm or rhizome.

We emphasize geophytes in groups that will bloom during sequential periods from mid-summer to fall. This column’s image gallery includes a sampling of my garden’s geophytes that bloom during this targeted period.

Here are some geophytes for sequential blooms during the targeted period.

Mid-summer

• Japanese water iris (Iris ensata)

• Lousiana iris (Iris giganticaerulea)

• Trumpet lily, such as the Easter lily (Lilium longiflorum)

• Oriental Asiatic lily, hybrids of Asian and Oriental lilies (example: Lilium ‘Kaveri’)

Mid-summer to fall

• Gladiola, sword lily (Gladiolus)

• Blazing star, Gayfeather (Liatris spicata)

• Elephant ear (Caladium bicolor)

• Tuberous begonia (Begonia × tuberhybrida)

• Water arum, Calla lily (Calla palustris)

• Swamp lily (Crinum spp.)

Late summer

• Abyssinian gladiolus (Acidanthera)

• Spider lily (Hymenocallis spp.)

• Orienpet (Lilium longiflorum x L. orientalis)

• Stargazer lily (Lilium orientalis)

• Trumpet lily, Easter lily (Lilium longiflorum)

Late summer to fall

• Canna lily

• Montbretia (Crocosmia x crocosmiiflora)

• African lily (Agapanthus africanus)

• Guernsey lily (Nerine)

• Dahlia (Dahlia coccinea x D. pinnata)

• Taro, elephant ear (Colocasia esculenta)

Fall

• Autumn crocus (Colchium speciosum)

To produce blooms in sequence during this period, these geophytes should be planted after the last frost in California’s Central Coast, which historically is March 1.

There is nothing magical about March 1. The critical issue is to protect these plants from exposure to freezing temperatures. Gardeners need to adjust their schedules to accommodate inexorable climate change.

Succession planting

A gardener could design companion planting bulbs for a succession of early, midseason and late spring varieties, which is the best way to enjoy continuing blooms. Starting this project in the fall could have included layers beginning with early spring-blooming bulbs, such as hyacinths, snowdrops and galanthus.

However, this column’s selection of geophytes is planned for summer and fall bloomers, and today is past the time for planting spring bloomers.Several plants in today’s column have larger mature sizes and could be planted in separate groups to extend the season.

It’s still possible to install two close sequential groups of the smaller geophytes: summer-blooming blazing star, Gayfeather (Liatris spicata) and fall-blooming guernsey lily (Nerine), montbretia (Crocosmia x crocosmiiflora) and autumn crocus (Colchium speciosum).

Prepare the planting site. Geophytes do best in fertile, well-draining soil with a neutral pH. Choose a location that gets full sun and prepare the ground for planting by loosening the soil, removing large rocks and pulling weeds. Turn compost into the soil or add a balanced, granular fertilizer.

Dig a trench or several large holes, depending on whether you want your bulbs to grow in rows or patches. Dig the hole deep enough to accommodate these two groups of bulbs, all of which are planted 3 inches deep. The bulbs could be interspersed or grouped. In either approach, they should be 4 to 5 inches apart.

A little about lilies

Lilies are several of the plants featured in this column. To learn more about the Lilium genus, visit en.wikipedia.org/wiki/Lilium.

Horticulturists recognize several groups of lilies species and hybrids. Asiatic, martagon, American, longiflorum, trumpet and aurelian, Oriental and Oriental hybrids. Botanists might have different groups, but from a gardener’s perspective, planning for lilies focuses on bloom times, height and blossom color.

Lilies bloom during summer, each group having a different peak bloom period. The gardener could plant lily groups in succession to extend the summer bloom season. Longfield Gardens has developed a helpful guide for this purpose. Browse at tinyurl.com/79w22a9x.

Advance your garden knowledge

This column’s list of geophytes was selected from a chart, “A Guide to Spring and Summer Bulbs,” developed by Longfield Gardens in New Jersey. The chart is accessible online at tinyurl.com/bdz8ww2w.

This column has drawn information from the website of Longfield Gardens, an online source of several of the geophytes listed. Browse longfield-gardens.com.

There are other online nurseries specializing in bulbous plants. Some include K. van Bourgondien (dutchbulbs.com), High Country Gardens (highcountrygardens.com), Spring Hill Nursery (springhillnursery.com), Eden Brothers (edenbrothers.com) and Brent & Becky’s Bulbs (brentandbeckysbulbs.com).

There are even more sources: search the internet for “bulb plants online.”

Enjoy your garden and particularly your summer geophytes!

Tom Karwin is a past president of Friends of the UC Santa Cruz Arboretum and the Monterey Bay Iris Society, a past president and Lifetime Member of the Monterey Bay Area Cactus & Succulent Society and a Lifetime UC Master Gardener (Certified 1999-2009). He is now a board member of the Santa Cruz Hostel Society and active with the Pacific Horticultural Society. To view daily photos from his garden, facebook.com/ongardeningcom-566511 763375123. For garden coaching info and an archive of previous On Gardening columns, visit ongardening.com.