So far I have had great success with some bulb type plants mixed in semp beds. I think the raised beds make it easier to manage the bulbs.
I was told Triteleia hendersonii) would take over the bed. This planting has been in the bed for about 5 years and has never attempted a take over.
Same with this one.
This one is very prolific, but easy to harvest the bulbs in the fall and move them to different beds.
Tulipa clusiana is not as prolific and plays well with the semps.
And one of my favorite bulbs to grow with semps:
Alliums in the semp beds:
I only grow the smaller types of allium and cut the seed heads off before they ripen.
