Planting

Assume you mean bedding plants? Look at your local weather forecast for coming weeks and plant when there is no frost forecast.
Generally it is best to wait until May.

After the last chance of frost, if they’re not hardy. Usually the second week in May.

I would agree with the second week in May. If the planter can be lifted, you could plant it earlier and put it in the garage or somewhere overnight if the weather turns cold.

If you can do so without breaking your back you could plant up the planters and keep them in the greenhouse overnight moving them outside unless the weather is inclement during the day. They will be nice and settled by the time they can be safely left outside once all frosts have gone.

Thanks starbird

Oh! Snap with liz