My Plants Are Regressing

 

A few weeks ago I bought a couple of dahlia plants to cheer myself up as the garden was so barren and void of colour.  I bought a beautiful deep velvety pink one and one that was red and white variegated - a bit like a raspberry ripple effect. The one above was the first I had my eye on.  Out in the garden its leaves quickly became ravaged with snails and slugs so I thought it would be best to bring it in at night.  I have watered and fed and tended it.  It stays in the garden during the day and comes in at night.

  

I recently noticed that one of the blooms had become two tone - or rather a few of the petals seemed washed out of colour.  Most strange.

The second dahlia I bought was the one shown above.  Beautiful quilled shaped petals that opened out into bi-colour.  I noticed that very quickly the flowers began to turn brown around the edges and die before they fully came out.  I deadheaded them hoping for a quick recovery.

Now look at what has happened.  Very strange salmon coloured flowers with a few red ones.  I wonder why just buying two random plants has resulted in some bizarre happening.  I wonder if some sort of cross pollination has gone on.  Any thoughts?