Lupines are a perennial I always notice and admire, but I’ve had no luck growing them in my own garden. They grow abundantly on the east coast and in other places (some may say too abundantly), but they do have a few “special requests.” I decided to ask a friend of mine who has grown lupines from seed for years in her Ontario garden for a few tips.
1) Lupines like acidic soil. Sphagnum peat moss, conifer needles, oak leaves, coffee grounds and ground sulphur will lower the pH of soil to some degree and help make it more acidic. However, I know gardeners in Ontario who have had great success growing lupines without ever purposefully lowering the pH of their soil (though they do add compost, which probably helps).
2) Lupines don’t like to be transplanted or have their roots disturbed. When growing from seed, try biodegradable pots, like the ones made from peat, that can be planted with the seedlings inside, or try a tactic that my friend uses. She sows her lupine seeds in big, six- to eight-inch (15- to 20-cm) deep trays. When they’re ready to transplant, she scoops under the seedling to avoid disturbing the soil and plants them quickly in a hole that has been thoroughly soaked and has sand and/or gravel in the bottom. Which leads me to the next important tip….
3) Lupines need good drainage. Try planting them on a high site so water drains away and doesn’t sit around their roots, or add gravel to the bottom of the planting hole. They won’t survive in heavy clay soil that retains water, but they can grow in hard-packed gravel. When starting seed, some people use sand as their growing medium, or you can try a thick layer of vermiculite in the bottom of the pots or trays.
4) Lupines send out a long taproot, anchoring itself to where it’s planted. When a seed is started in a pot, the first thing it will do after sprouting is send a taproot out the drainage hole and form a knot, which you can’t disturb without potentially killing the plant. You can try starting seeds in deep trays with no drainage holes and lots of vermiculite and gravel to improve drainage around the roots, or try cutting the container off from the taproot before planting.
5) Tip #4 means that growing lupines in containers can be tricky. However, I like to tell myself that you can grow just about anything in a pot if you overwinter it properly, and after seeing it done successfully in the past, I placed my lupine in a deep pot this year, with lots of drainage.
6) Lupines will self-seed, and you can divide them in the spring, but not in the fall. If you wish to save the seeds to sow at another time, wait for the green seed pods to turn brown and dry out. You can then pick the pods and save the seeds within. If you wait too long, though, the pods will explode and release the seeds themselves.