Agapanthus - Mysterious Disappearance

I bought four Agapanthus plants last Fall and planted them on the east side of the house. They thrived and two of them put out long flower spikes late last month. They started to open last week, so I checked on them today. Disaster! Nipped off cleanly!

You can see the barren spike behind and to the right of the Canna bloom and one lonesome Agapanthus flower on the Canna leaf.

Here's a closer shot of the Agapanthus spike.

Something similar happened to a fresh new Bouganvilla that I planted in the ground near a trellis. The thorns on it had not yet developed; one morning it was trimmed off at the ground.

Damned deer! Nibbled on a few Zinnea flowers, too, but didn't seem to like them.