Blackberry lily is normally planted in the spring from potted nursery plants or bare roots purchased from online sellers. They can also be planted from seeds, though it may take three years to achieve flowering plants in this way. Bare roots will generally mature into flowering plants in their first season, though it sometimes can take two seasons. Native to parts of India, China, and Russia, blackberry lily is a fairly short-lived perennial, but its rhizomes will spread gradually to sustain the plant in the garden. And it will also self-seed, creating an ongoing colony of plants. All members of the Iris genus contain compounds that are mildly toxic to humans and to pets. If planting bare rhizomes, space them about 3 to 4 inches apart (6 to 9 per square foot) and 5 inches deep. Water well until they are established, but after that, these plants will do better without excessive watering. The flower stalks can get quite long, and may require staking to prevent them from blowing over in exposed locations. Provided the plant is grown in its recognized hardiness range, no winter cold protection is needed.
Light
Choose a site with full sun to grow your blackberry lilies. A minimum of four hours a day is necessary for plant health and good blooms, and six hours is even better.
Soil
Having the perfect soil isn’t important for growing blackberry lilies, but having good drainage is. Soggy soils, especially in winter, can cause the rhizomes of blackberry lilies to rot. These plants are not fussy about soil pH; they will do well in both slightly alkaline, neutral, and slightly acidic soil conditions (pH 6.1 to 7.8). Poor soils tend to make the plants shorter; in rich soils, they will be taller.
Water
While blackberry lilies respond to regular watering by producing larger, healthier blooms, they are also drought tolerant. Dry winter soils are ideal. Err on the side of less water, not more. If your garden is getting rain every week or two, extra irrigation is rarely necessary. During drought periods, 1/2 inch per week is entirely adequate. Water should be cut back during the dormant winter months to discourage root rot.
Temperature and Humidity
Blackberry lily is generally considered hardy in USDA zones 5 to 10, though zone 4 gardeners often grow it successfully, as well. Hot weather and high humidity are not issues for cultivating the blackberry lily. The plants are not susceptible to mildews or fungi, provided no standing water is present.
Fertilizer
Supplemental fertilizer is not necessary to grow blackberry lilies. The plants are not heavy feeders, and can get the nutrients they need from the soil. In poor soils, a single spring feeding with a balanced organic fertilizer—or a synthetic fertilizer formulated for blooming plants—is sufficient.
Types of Blackberry Lily
Until 2005, this plant was categorized as Belamcanda chinensis, and some sources may still list it under that name. But genetic sequencing demonstrated that this plant is an Iris species, and today is officially listed as Iris domestica. In addition to the pure species, there are two named cultivars commonly grown:
‘Hello Yellow’: This is a dwarf cultivar with leaves growing only 10 inches tall. The flower spikes rise to 20 inches, topped with unspotted, butter-yellow flowers.‘Freckle Face’: This is a more prolifically blooming version of the species plant, producing as many as 12 blossoms per plant.
Blackberry lily is not a common offering at most garden centers, so you may need to seek out a specialty nursery or purchase from online retailers, who sell either rhizomes or seeds.
Pruning
Although blackberry lily does not require “pruning” in the formal sense, removing the seed capsules as they form will prevent them from ripening and casting seeds into the garden, where you will need to pluck out the volunteers. Cutting back the flower stems after they fade may help prolong the bloom period with new blossoms. At the end of the growing season, remove the yellowing foliage to tidy up the garden and eliminate fungal spores and nesting areas for pests.
Propagating Blackberry Lily
Similar to the way that iris or daylily rhizomes can be divided, you can propagate blackberry lilies in the same way—by digging and dividing the root clumps. This is best done when the flowering is over and the plants are mostly done growing—in late summer or fall. Here’s how to do it: Division every few years will also help keep the clump healthy, as individual plants are not long-lived without regular division.
Growing Blackberry Lily From Seed
Blackberry lily can easily be grown from seeds collected in fall from the berries that remain when the seed pods dry and break open. It is best to chill the seeds in the refrigerator for several weeks before planting them. Sow the seeds indoors in mid to late winter in a seed-starter mix, covering them with 1/4 inch of mix. Keep the pots well-watered in a bright location until the seedlings sprout. Move them to a sunny location and continue to grow them, watering when the soil gets dry. When the weather warms in the spring, move the pots outdoors and continue to grow them until they are well established. At this point, they can be transplanted into the garden. If you sow seeds directly in the garden, do it in late fall or early spring, as soon as the ground can be worked. Fall-sown seeds may flower in the first year, but seeds sown in the spring will probably not flower until the second year. Blackberry lily self-seeds quite easily, and it is an easy matter to transplant some of the tiny volunteer seedlings to new locations.
Potting and Repotting Blackberry Lily
Growing blackberry lilies in containers is a great way to “stage” the plants when they come into bloom: Before blooming, place the containers in an out-of-the-way spot, as the foliage is not much to look at. When the blooms begin, move the containers to a prominent spot on the porch or patio where you can enjoy the flowers. Plant up two or three blackberry lilies in the same pot to give a full look. Use well-drained potting soil in any container with good drainage. Arrange the rhizomes close to the soil’s surface so that they are not touching. Divide and repot the lilies as they expand and become crowded. Repot in late summer, when growth slows down. In most climates (freezing temperatures and snowfall), dormant plants in their pots can usually be stored in a sheltered but cool outdoor area for the winter. Zone 5 gardeners, however, may find that potted blackberry lilies perish over the winter unless moved into a garage or basement, as plant roots are more vulnerable when they are above ground in pots.
Overwintering
Most gardeners will not find it necessary to give these plants any winter protection against cold, though if you are trying to cheat the standard zone recommendation by growing blackberry lily in zone 4, then a winter layer of mulch may be a good idea. The black seed berries on this plant can be attractive in winter, so many gardeners allow the flower stalks to remain as snows arrive. This will, however, encourage self-seeding in the garden, so if this is not to your liking, then it’s best to clip off the flower stalks before they can go to seed.
Common Pests & Plant Diseases
Blackberry lilies are generally trouble-free plants. However, the common iris borer can infect and even kill plants. The pest is insidious and may leave no signs at first except an entry hole at the base of the plant. If your plant looks wilted or discolored, look for this hole. Remove and destroy any infected plants, roots and all. Root sections can be salvaged by closely inspecting them and cutting away any rotting sections or areas with borer holes. Root rot may occur if blackberry lily is grown in soil that does not drain well, or if the plant gets too much water. This is a common problem in extremely wet climates. Badly affected plants will need to be removed and discarded.
How to Get Blackberry Lily to Bloom
Blackberry lily blooms only last a day or two, but deadheading will promote additional blooms, so you can achieve a color display for several weeks in mid to late summer. Failure to bloom can usually be traced to one of several reasons:
Plants are too young. It’s not uncommon for newly planted rhizomes to not flower until their second year, and plants started from seeds may be shy until their third year.Not enough sun. Like most iris, blackberry lily needs at least four hours, and preferably six or more hours, of direct sunlight each day in order to produce ample blossoms.Too much fertilizer. Unlike many flowering plants, blackberry lily prefers to get its nutrients from a naturally rich soil. Too much artificial fertilizer can actually cause fewer flowers. At most, these plants should be fertilized once in the spring with organic fertilizer or flower fertilizer. More than that may lead to disappointing results.
Common Problems With Blackberry Lily
Other than iris borer and root rot caused by excessively moist conditions or dense soil, blackberry lily is a relatively problem-free plant. Some gardeners find themselves disappointed by the relatively short bloom period and rather subtle display. This is not a great plant for gardeners looking for spectacular long-lasting color, but it can be ideal for those looking for interesting diversity in the garden. The most common problem is that the tall flower spikes can be prone to toppling over in windy conditions, so it is best to stake them, especially in exposed locations.
