Mine got about 6 feet tall and wide before I removed them from this bed. It was spreading below the ground as well as from branches that rooted when they touched the ground. There were 4 bushes in here. I am quite a bit south of you, so they may not be quite as vigorous with spreading up there.

{{gwi:819125}}

it also seeds itself.

The only thing it does in my yard is DIE!!!....LOL!

Mine is under an awning so it stay pretty dry there. Mine has never seeded itself or spread. Maybe if it got more water it would?

I have probably 50 of them and going to add 100 more, I love them......they attract the butterflies, are drought tolerant and fast growing. I have NEVER seen a single seed on the plants even with probably 100,000 flowers so far. They mostly just extend across the ground by the limbs getting longer and unless you anchor a limb down and put soil over it they don't seem to willingly root with just simple soil contact.

Mine reseed themselves. I had 2 and now have them all over my yard where I have transplanted the babies. Maybe it has to do with the variety.

I'm in Southern California....My little Plumbago plant spread apparently by some rhysome-looking underground lateral roots, (not unlike bamboo). The entire hill behind my house was taken over within 2-3 years, despite efforts to 'control' it, allowing other shrubs to co-exist.... HA! ...Stuff's UNSTOPPABLE! Now it's up in the trees, and over the fence, and into the neighbors' yards ==== und maybe tomorrow der Vorld. Good luck!