Lupines are a tall garden plant with spikes of spectacular clumps of flowers and strong lush foliage. Lupines bloom in early summer and there is a large variety of colors of lupine flowers. There are both annual and perennial varieties. They need lots of sunlight and slightly acidic well-drained soil. Mature lupines are hardy garden plants, but their seeds take a long time to germinate and the seedlings can be weak. In most climates, it’s best to sow lupines indoors and plant them out when the plants are established and the weather is warm.
Sow lupine seeds at least 8 weeks before you plant to transplant them out into the garden. Germination can happen at anytime from 2 to 8 weeks, so be patient.
Soften the lupine seeds’ shells by rubbing them gently with very fine sandpaper. Soak the seeds for up to 24 hours prior to germinating. When the seeds swell, take them out of the water and plant them while they’re still wet. Lupine seeds are similar to pea seeds in that they’re very hard-shelled, so germination will be faster and more successful if you soften up the shells first.
Plant the seeds about ½ an inch deep in flats filled with a good potting mix that hasn’t had any lime added to it. Potting mixes with peat or compost work well. Water the seeds in.
Keep the pots moist and put them in a sunny place. The optimum temperature for incubating lupine seeds is about 60 degeres F.
Transplant lupine seedlings into the garden in late spring, when there is no danger of frost or very cold nighttime temperatures. Lupine seedlings can be slow to take off, so don’t transplant them until they’re about 4 inches tall.
Choose the strongest plants and place them about 6 inches apart. Thin them to 12 inches when the plants are about a foot tall.
Keep lupines well-watered while they’re blooming. Aside from watering, they don’t need much special care once the plants are established.