Hi
I planted Tulips bulbs 7 years ago and they have been coming every Spring no problem. Last year, I planted Sedum goldmoss ground cover in that area. Right now, I do not see any sign of Tulips where the area is covered by Sedum; however I see sign of Tulips in the area which is not totally covered by Sedum. Can Sedum stop Tulips from coming out? Thank you very much.
Thank you for contacting the Toronto Master Gardeners. Tulips can be grown successfully (and look fantastic !) with groundcovers, depending on which groundcover and which tulip.
Sedum goldmoss (Sedum acre) grows to about 3” tall, and is mat forming. It spreads aggressively, primarily by underground rhizomes, and can overwhelm plants of similar height. The groundcover should be no more than half the height of the tulips. If your tulips are small and delicate looking, with narrow leaves and small flowers, they could have trouble pushing through the rhizomes and mats of S. acre. It could also be that the sedum is blocking direct sun for the tulips.
The most popular tulips today are hybrids (the original tulips are species tulips). Hybrid tulips are typically spectacular looking, in many shapes and colours. However hybridizing has weakened the ability of these tulips to rebloom in successive years, and many gardeners treat hybrid tulips like annuals, replanting new ones each fall. Species tulips are hardier than hybrids. I think 7 years of reblooming is a long time if you have hybrid tulips, so maybe they are finished blooming in that part of your garden and need to be replaced.
S. acre is shallow rooted and easy to pull up and replant elsewhere in the garden. You might want to try removing or at least thinning your sedum in the part of your garden where tulips have not appeared yet, and see what happens. It is still early spring, with the typical temperature swings, so it could be that your tulips will still appear, either through thinned out or removed sedum, or perhaps with the sedum in place as it is now.
If you want to consider another groundcover to replace your sedum, here is a link where you can find a list of native groundcovers :
Canadian Wildlife Federation – Native Plant Encyclopedia
The Toronto Master Gardeners also have a Garden Guide for Growing Tulips that has ben recently updated and might be useful. Here is a link :
Growing Tulips: A Toronto Master Gardeners Guide
Good luck with your tulips !