obelia cardinalis, commonly known as cardinal flower, is a native perennial plant that can be grown from seed with some specific care. Here's a guide for sowing Lobelia cardinalis seeds both outdoors and indoors, as well as general care tips:
Planting Outdoors (Fall & Spring)
Site Selection
Choose a partly shaded to full sun location. Lobelia cardinalis thrives best in areas with partial shade, particularly in the hotter summer months, but it can tolerate full sun in cooler climates.
Ensure the site is moist, well-drained, and protected from strong winds. Wetland or streamside areas are ideal.
Soil Preparation
Prepare the soil by adding organic matter (like compost) to improve drainage and fertility.
Aim for slightly acidic to neutral soil (pH 6.0-7.0).
The soil should be moist but well-drained, as Lobelia cardinalis does not tolerate dry conditions.
Planting Depth
Surface sowing is best, as the seeds need light for germination. Sprinkle the tiny seeds evenly across the soil surface, then lightly press them in or cover with a thin layer of fine soil or sand.
Do not bury the seeds deeply.
Watering
Keepthe soil consistently moist throughout the germination process. Water gently to avoid washing away the seeds.
Once established, cardinal flowers are moderately drought-tolerant, but they prefer consistent moisture, especially during the growing season
Stratification & Scarification
Stratification: Lobelia cardinalis requires cold stratification (chill) to break dormancy. For outdoor sowing in the fall, you can simply plant the seeds and let winter's cold naturally do the stratification for you.
If sowing in the spring, pre-chill the seeds by placing them in a moist paper towel or sand in the fridge for 30-60 days before planting. This will mimic the natural winter conditions.
Scarification is not necessary for Lobelia cardinalis seeds.
Timing
Fall Sowing: In colder climates, sow seeds in late fall, as they will naturally undergo the cold stratification needed for germination.
Spring Sowing: If sowing in the spring, start early enough to allow stratification, then plant once the soil has warmed.
Maintenance
Once plants start growing, thin seedlings to ensure proper spacing (6–12 inches apart).
Keep the area free of weeds and make sure the plants get enough water during dry spells.
Mulch around the plants to retain moisture and keep the soil cool.
Cardinal flowers may need staking or support if they grow tall or in windy locations.
Starting Seeds Indoors (Spring for Later Transplanting)
Planting Containers
Start seeds indoors 6-8 weeks before the last expected frost in your area.
Use seed trays or small pots with good drainage.
Soil & Planting
Use a well-draining seed-starting mix. Moisten the mix before sowing the seeds.
Sprinkle the seeds on the surface, press lightly, and cover with a thin layer of soil or sand.
Keep the soil moist but not waterlogged.
Place the containers in a location that receives bright, indirect light or use a grow light.
Stratification
As with outdoor sowing in spring, cold-stratify the seeds by placing them in the fridge for 30-60 days if you didn’t do it in advance.
After stratification, bring them back to room temperature and continue to care for them until germination.
Germination
Germination typically takes 2-4 weeks under optimal conditions (65–70°F or 18–21°C).
After germination, provide enough light to prevent seedlings from becoming leggy.
Transplanting Outdoors
Once the seedlings have grown large enough to handle and the threat of frost has passed, harden them off by gradually introducing them to outdoor conditions over a period of 7–10 days.
Transplant them into the prepared outdoor bed, spaced 6–12 inches apart.
Invasiveness
Lobelia cardinalis is not considered invasive. It is a native species in the USA, commonly found in moist, woodland, and riparian habitats. However, it can self-seed and spread over time if conditions are right, but it generally won’t outcompete other plants in a well-managed garden.
By following these steps, you can successfully grow Lobelia cardinalis and enjoy its striking red flowers that attract hummingbirds and pollinators.
Dark Green indicates the plant is native within the state, yellow rare, the lime green indicates where the plant is native and seen more within a state.
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