How to Grow Summer Bulbs for Superb Garden Impact ‐ Don Kinzler

The term “bulb” is a nickname often given to any plant with enlarged, fleshy underground structures that go dormant part of the year. Types of “Bulbs” ‐ Corms ‐modified stems flattened on top with no visible storage rings when cut in half. Original corms shrivel during growth and produce new corms. (Gladiolus) Rhizomes ‐ underground stem with multiple growing tips. (Canna, calla lily) Tubers ‐ swollen stems that are covered with buds (aka “eyes”). (Tuberous begonias, Caladium) Tuberous roots ‐ resemble tubers but are swollen roots. The buds are at the base of the old stem on the tuber. (Dahlias) True bulb ‐ Onion, Easter Lily “Summer bulbs” are “tender,” meaning they do not survive our winters and must be dug and stored in a cool, frost‐free area for the winter. Their bloom time is summer, as the name implies. Shopping for summer bulbs:  Reputable mail‐order companies, local garden center.  Beware national chains whose bulbs are on store shelves in February, deteriorating the longer they sit at high temps.  Larger bulbs produce larger blooms. Select firm bulbs free from soft or rotting spots. Planting Time: Plant to avoid frost. If bulbs are direct‐planted outdoors on May 10, by the time they emerge from the soil, likelihood of frost is past. Some are best started early indoors between April 1‐15, such as canna, tuberous begonia, calla lily and dahlia. Preferred soil: Good soil drainage and aeration are essential. Add 2‐3 inches of compost, peat moss or other organic matter and work into the top 12 inches of soil before planting, and incorporate fertilizer at planting. Planting Rules of thumb: The pointed end goes up. Planting depth is measured from the bottom of the bulb to the soil surface. Bulb size dictates the depth; the larger the bulb the deeper the depth. Types: Canna ‐ Bulb type ‐ rhizome. Height ‐ 18 to 30 inches up to 5 to 7 feet.  Exposure ‐ full sun. Planting Depth ‐ 4 inches. Spacing – 12 to 18 inches apart.  These popular plants have an extended flowering period and luxurious green, striped or bronze foliage. New dwarf cultivars may reach only 2 feet tall.  Cannas bloom from early summer until frost if you remove old blossoms regularly so they do not set seed.  Divide rhizomes in spring if you want to increase your plants. Gladiolus ‐ Bulb type ‐ corm. Planting Depth ‐ 2 to 3 inches. Spacing ‐ 3 to 6 inches apart. Height ‐ 24 to 36 inches.  Full Sun. Often grown as cut flowers. Space planting times a week or so apart to have gladiolus in bloom the entire summer.  Glads can be planted by digging out a trench and planting corms in either a single or double, staggered row.  To keep plants erect, they must be staked. Hilling up soil on both sides of the row also gives good support.  Cut the flower spike when the first floret is showing color for the best quality cut flowers. Be sure to leave at least two, and preferably four, leaves on the plant after cutting spikes to help corms mature properly.  The most troublesome pests are gladiolus thrips. This insect causes malformed and spotted flowers. Shake corms with Sevin insecticide in paper bag before storage, and again before planting. Dahlia ‐ Bulb type ‐ tuberous root. Planting depth ‐ 3 to 8 inches. Spacing ‐ 1 to 3 feet apart. Height ‐ 9 to 48 inches.  Exposure ‐ full sun. Plants normally bloom from midsummer until frost.  Start early indoors between April 1 to 15.  Pinch out the tips of the main stems three weeks after planting (when about 6 inches tall) to produce strong, bushy plants. Remove faded blooms during summer months to encourage continuous blooming. Tall dahlias need staking. Caladium ‐ (Elephant ears, Angel wings.) Tubers. Planting Depth ‐ 1 inch. Spacing ‐ 8 to 12 inches. Height ‐ 6 to 24 inches.  Exposure – Morning sun to 50% shade. Start indoors in spring 4‐6 weeks before the average last frost or purchase potted plants. Place the knobby side with the eyes up (both roots and shoots emerge from the top of the tuber) and barely cover with soil. Tuberous Begonia ‐ Bulb type ‐ Tuber. Height – 1 to 2 feet. Plant tuber about 1 inch deep.  Exposure ‐ shade. Require rich, organic soil mix, well‐drained.  Start indoors 4 to 6 weeks before frost. (Start about April 1‐15.) or purchase plants. Calla Lily (Zantedeschia) ‐ Type ‐ rhizome. Height ‐ 12 to 24 inches. Planting Depth ‐ 2 inches. Spacing ‐ 12 to 18 inches.  Exposure ‐ Full sun to 25% shade. Not for hot dry locations.  Start early indoors 4‐6 weeks before last spring frost (April 1‐15) or buy started plants. Alstroemeria ‐ Planting Depth ‐ 2‐3 inches, Spacing ‐ 12 inches. Height ‐ 12 to 24 inches.  Exposure ‐ Full sun to morning sun. Elephant ear (Alocasia) ‐ Bulb type ‐ bulb. Planting Depth ‐ 3‐4 inches. Spacing ‐ 24‐36 inches. Height ‐ to six feet.  Exposure ‐ Filtered light. Start early indoors 4‐6 weeks before last spring frost. (Ismene) – Peruvian Daffodil  Unique because they can be timed fairly precisely to bloom, for weddings, etc.

Digging Bulbs: At about the time of the first frost in fall. Tops can get lightly frosted, but then dig within a day to avoid rot. Use a spading fork to lift the bulbs from the ground. Shake off excess soil, wash only if muddy. Avoid breaking, cutting or damaging the storage organs. Curing Bulbs: Allow excess moisture to dry in a warm location out of direct sun, 60 to 70 degrees  Gladiolus corms ‐ cure about a week, then remove old corm.  Tubers, Tuberous roots, Rhizomes ‐ Cure for a few days. Don’t allow to desiccate or shrivel. Storage: Label bulbs.  Store these dry: Gladiolus corms. Paper bags or shallow trays at 35 to 40 degrees.  Store these so they don’t desiccate and shrivel: In a cool basement, store in peat moss, dry sawdust or other medium to prevent desiccation. Cannas and dahlias at 40° to 45° F. Tuberous begonia, caladium, and calla lily at 50° to 55° F.

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