You could wait 2-3 weeks after your average date of last frost in Spring.

For example, the avge for the Dallas-Fort Worth Area, where I live, is March 13th so I wait a few weeks until the 27th or sometime in early April.

That habit helped me with a potted hydrangea that I currently have because today (3/24) we are expected to dip below freezing so I had to move the pot back indoors even though during the last few weeks we got quite high (the 80s).

Just a fyi: I almost planted it this morning. Sometimes a little dip that quickly bounces back up is not a big deal but if it had gone down much more than that, the leaves would have been affected. In a scenario like today, if I had planted it, I would probably cover it to protect it.

Luis

Luckily I am in northern california and we are in the high 60s to low 70s consistently now with a windy day here and there but no where close to freezing. So I am guessing planting them should do no harm. Thanks again for the speedy reply

If your hydrangeas have been outdoors in pots and acclimated to the weather you could plant them any time your soil is workable, meaning not overly saturated with winter or spring rain to the point you could ruin the soil structure spading it. It's the wet, not the light frosts we still may have, delaying putting container plants in the ground for me here in coastal washington.

If these are florists hydrangeas that have never been outside, the temperature/wind would have to be considered, and you'd want to gradually introduce them to the real world before installing them in the ground, much like you would ready an annual plant not hardened off to fluctuating temperatures or, as damaging if they've never been exposed to it, wind.