The blue lupine plant is a hardy perennial that grows up to 3 feet high and is native to the northern areas of North America. The plant is favored in partially shaded gardens, as it produces deep blue flower spikes in the spring that attract butterflies. Lupine plants require a well draining soil and are sensitive to over-watering and high temperatures.
Propagate perennial blue lupine plants by collecting seeds from pods that grow on the plant after flowering in the months of June and July. Dry the seeds and store them in a paper envelope until ready to plant.
Process the seeds for planting by scarifying with sandpaper to make a scratch on the seed. Stratify the seeds by placing them on damp paper towel in a plastic bag. Set the seeds in a refrigerator for 10 days to complete the stratification process.
Choose a planting location for the blue lupine perennial plant that has an acidic soil that is well draining. The area should receive full sun to partial shade light conditions for best results. Test the soil pH, as the plant grows best in a soil pH of 5.6 to 7.5.
Amend the soil by working in ground rock sulfur to lower the pH number if needed. Apply water to dissolve the sulfur and let the soil rest for two weeks prior to planting.
How to Plant
Prepare the planting area by removing all weeds and vegetative growth and working 2 to 3 inches of organic compost into the soil to increase the nutrient content and moisture retaining qualities.
Sow lupine seeds into the soil at a depth of 3 millimeters just before the last frost in the spring as soon as the soil begins to warm. Space the rows 6 to 18 inches apart.
Care and Maintenance
Water blue lupine plants frequently to keep the soil moist during the growing season. Fertilize the plants with a low nitrogen and high phosphorus fertilizer each month during the growing season to promote flowering.
Excess nitrogen will produce heavy foliage and few flowers. Remove all spent flowers to stimulate more blooms on the plant.
Monitor the blue lupine plants for an infestation of slugs under the leaves and near the soil surface. Apply slug-removing pellets or place slug traps around the plants to eliminate the pests.
The plant has few insect problems. Do not over water or allow water pools around the stem of the lupine as this will cause root rot and kill the plant.