[Yana]

I got hold of a lot of spring bulbs towards the end of last year and planted them into large plastic planters. The planters / pots are sitting in the greenhouse at the moment covered in newspaper and one or two of them are starting to show green tips of the bulbs. I've removed the newspaper from those that have and kept the others covered until they have green tips showing.
If I move them outside they are going to get waterlogged as the rain does not seem to be easing up and colder weather is forecast next week. I have put good drainage in the bottom of each planter. I really potted them up for outside as I wanted a good show of colour to brighten the garden up (the planters are used for veggies later in the season) so if I keep them in the greenhouse (unheated) too long will this be detrimental to them eventually going outside? 

[Goosegirl]

Beside your drainage, I would put them on bricks or something so any excess water can drain out. Spring bulbs are pretty hardy but hate being water-logged. I would remove their covering but would have some bubble-wrap handy in case the weather really turns very cold.

[Yorkie]

Are there actually holes in the plastic planters?  If so, then as GG says they should be fine outside if they are outdoor bulbs - perhaps harden them off a little if it suddenly gets cold overnight in the first few days after putting them out - and I agree with the suggestion to raise them on bricks or similar so that water can drain better.