Dwarf larkspur (Delphinium tricorne) can be found in the wild growing in woodlands, roadsides, and wastelands all over its native eastern USA. The plant’s showy purple flowers encourage ornamental growth and attract butterflies and hummingbirds. The plant’s name tricorne refers to its three-horned fruit pods.
I. Appearance and Characteristics
Delphinium tricorne, known by the common names dwarf larkspur or spring larkspur, is a species of flowering plant in the Ranunculaceae (buttercup) family. It is native to the central and eastern United States, where it is the most common Delphinium found.
The genus name, Delphinium, comes from the Greek word for “dolphin”, and may refer to the shape of the flowers. The specific epithet, tricorne, is Latin for “with three horns”, which describes the shape of the fruit.
D. tricorne is a perennial plant that grows to a height of 15–45 centimeters (6–18 in), with a thin flowering stalk rising from a group of basal leaves. There are a few alternate leaves along the stalk. All the leaves are grayish green to green, and deeply divided into about 5 lobes that are then each divided further into 2 or 3 secondary lobes. The basal leaves are up to 10 centimeters (4 in) long and across.
The inflorescence is a raceme at the end of the stalk consisting of 6 to 24 flowers that are violet, blue, white, or a mixture of these colors. The flowers have 4 to 5 sepals and a long, narrow spur in the back. They are 1–1.5 inches (3–4 cm) long.
The plant is pollinated by bumblebees and hummingbirds, and several other species of bees visit the flowers for nectar and pollen.
Toxicity
The diterpenoid alkaloids lycoctonine and tricornine (otherwise known as lycoctonine-18-O-acetate) have been isolated from D. tricorne. The toxicology and pharmacology of lycoctonine have been quite well studied, but there is only limited information available concerning the biological properties of tricornine. Both alkaloids have neuro-muscular blocking properties, and D. tricorne should be treated as a potentially poisonous plant. This species has long been regarded as poisonous to livestock.
II. How to Grow and Care
Sunlight
Dwarf larkspur requires 6-8 hours of sun per day, preferably morning sun. Additionally, proper air circulation is needed for disease prevention. Plant dwarf larkspur where the sun shines at least half of the day.
Temperature
Dwarf larkspur requires cool summer conditions for proper growth and does not do well in hot, humid conditions (except for a few exceptional hybrids). Flowering can be induced by the day-night temperatures between 2 to 16 ℃. Growth and flowering requires constant moisture, so water dwarf larkspur at least weekly. More caution should be observed during dry summer periods.
Watering
Thriving in its native woodland settings, dwarf larkspur has adapted to periods of moderate moisture followed by natural drying cycles. This species exhibits a preference for consistent moisture without being waterlogged, indicative of its resilience to the varying humidity levels it encounters in situ. For optimal growth, watering every week is recommended to mimic these conditions. As an herbaceous perennial commonly grown outdoors, dwarf larkspur’s growth cycle is closely tied to water availability, with peak vitality during the rainy spring season when hydration cues spur vigorous development.
Soil
Dwarf larkspur needs humus-rich, well-drained, moist soil for proper growth. Seeds will germinate in these optimum soil conditions. Start plants in plug trays having soil with sterilized peat moss, perlite, and vermiculite at ratios of 1:1:3 or 2:0:3, and with a pH of 5.5-6.5. Keep soil wet until roots are established.
Prepare the garden site by adding a foot-deep layer of compost and digging a hole twice the diameter of the pot. While backfilling the hole, the root ball of the plant should be level with the surface of the soil. Applying organic fertilizers to the soil and using grit can help prepare soil for dwarf larkspur.
Fertilizing
For healthy growth and vibrant blooms, fertilize dwarf larkspur in spring with balanced nutrition, switching to high phosphorus before flowering. Apply monthly, using dilute solutions to avoid root burn—typically 1/4 strength of the recommended dose. Overfertilizing can harm dwarf larkspur, so observe growth responses and adjust as needed. Seasonal changes dictate less frequent applications in autumn, none in winter dormancy. Always water dwarf larkspur before fertilizing to prevent nutrient overload. Proper fertilization enhances vigor and bloom quality in this beautiful species.
Planting Instructions
Sow dwarf larkspur in early spring or early fall. Start seedlings indoors in plug trays. For seeds to germinate, water, fertilizer, and temperature must be consistent. Pre-cool seeds at 7 ℃ to increase germination; then keep them at 16 to 20 ℃. It’s germination will takes 5 to 6 weeks.
After germination, keep the temperature around 25 ℃ during the day and 16 ℃ at night until 1 or 2 true leaves emerge, and then 10 ℃ at night to avoid premature flowering. Young plants can be taken to the garden for fall planting 5-6 weeks from the emergence of root or germ. Plant seedlings 46 to 61 cm apart.
Pruning
For best flowering, prune new plants to 2-3 spikes per plant, or 5 to 7 spikes per plant in established plants. Once the flowers wither, cut the spike to the size of the smaller shoots of the plant for a second round of flowers in late summer or early autumn. Once the plant wilts in the autumn, prune it completely to the ground.
Propagation
Dwarf larkspur is a herbaceous perennial that flourishes in woodland settings. Propagation is typically achieved through sowing fresh seeds directly in fall, as they require a period of cold stratification to germinate effectively. For optimal results, gardeners should sow seeds in well-draining soil rich in organic matter, with consistent moisture but avoiding waterlogged conditions. Thinning of seedlings might be necessary to provide ample space for growth, ensuring adequate air circulation to reduce the risk of disease. Careful handling is important since this plant has delicate roots that are easily disturbed.
Transplanting
The prime period to transplant dwarf larkspur ranges from mid-to-late spring, a time when growth cycles resume vigorously. Ensure a spot with partly shaded conditions to cultivate its potential. Gentle handling during relocation will help maintain its delicate root structure.
III. Harvesting and Storage
During peak summer months, dwarf larkspur flowers can be harvested for ornamental uses. Use sharp gardening scissors to cut at the base of the scape (or stalk), and prune the base of the flower branch obliquely at 45° to increase the water absorption area. Arrange in a vase with clean water promptly.
