We’ve been visiting our sons in Vancouver for a number of years, and really liked the California Lilacs that we’ve seen. On our last trip last April, we bought a small one at a Vancouver nursery and smuggled it back in our carry on luggage – we live in London ON. We put it in a large pot, and it thrived (increasing in size by about 4x) during the summer situated on our sunny front porch. We realize that it is too cold in our area for it to survive the winter outside. We moved it into the house about 5 weeks ago, and put it in the sunniest window available. I have a cool mist humidifier going in the room (we have a forced air furnace), and it seemed to be doing well until a few weeks ago. It now seems to be drying out, and has dropped many leaves (it’s being watered regularly). Would we be better off placing it in our basement cellar (no light, temps are cold, but not below freezing), and let it go dormant rather than leaving it where it presently is?
Any help would be appreciated. Thanks.
Thank you for your question.
I suspect that your plant is the most popular variety of California Lilac available in Southern British Columbia, California Lilac Victoria, Ceanothus thyrsiflorus ‘Victoria’. This evergreen to semi-evergreen shrub native to California has bright blue flowers in late spring thru summer and leathery shiny green foliage.
These plants are drought tolerant and perform best in full sun and well drained soil with consistent rainfall. They dislike heavy pruning and soil disturbance. So, the leaf drop could be due to recent pruning or repotting. If you repotted the plant recently, did you use a quality potting soil with good drainage characteristics? (Given the plant growth over the summer, the soil used for your original repotting should be suitable.)
As you realize, California lilac will not survive a London winter outdoors, and must be moved inside. Given it is an evergreen plant, I suggest that you keep the plant in a sunny area over the winter. Humidification may not be necessary.
Water the plant consistently, using room temperature water. Add water to the pot until the water runs out the bottom of the pot, and then remove the extra water. Never leave the pot standing in water. Watering should leave the growing medium slightly moist but not saturated. Water again only when the soil has dried out.
Additional tips on watering can be found in the Toronto Master Gardeners’ Houseplant growing guide: