I planted some gladioli 18 months ago, and last year they grew tall and colourful. However, they've just begin flowering this (second) year and so far they're arriving with the stems curled/folded up, with the flower heads pointing downwards. They're also only about a foot tall. And so far they're flowering yellow too. Last year they were multi-coloured dahlias with various reds, oranges and whites.
What's gone wrong?