My latest average date of last frost in the Dallas Area is mid-March (13th) so yours would be a tad before mine. Feel free to wait around two extra weeks after your ave. date of last frost and then give them some fertilizer.

About 1/2 to 1 cup of compost, composted manure or cottonseed meal. Or Osmocote with a NPK Ratio of around 10-10-10. A single application of these slow-release fertilizers in the Spring should be enough for the whole year. Hydrangeas are not hungry shrubs like roses so they will done fine with that and decomposing mulch. Assuming your soil is not deficient of minerals, you could also skip fertilizing some years and nothing bad would happen.

Because our soil is alkaline, I would also always amend the soil with acidifying compounds in Spring. Think: greensand, aluminum sulfate, garden sulphur and iron-chelated liquid compounds.

If you feel like feeding the plant something later in the year, use "weak" fertilizers like liquid seaweed, liquid fish or coffee grounds. I get coffee grounds from Starbucks. ;o)

Check mulch levels now and see if the plants also need more mulch for the new growing season. My mulch just seems to disappear with time. I know it decomposes but -I think- some of my pooches may eat mulch too. Lord. :o)) You can maintain 3-4" of mulch up to or past the drip line. I go past the drip line since it gets warm here and slow summer winds can dry the plants in their first few summers.

Last suggestion... if you have never done a soil test or did one more than 5-10 years ago, consider if there is $$ in the budget for another one.

I got hit by the cold spell on Jan 5th too. Bottomed at 19F after weeks in the 50-70s. Many hydrangea shrubs here -in unprotected locations- show growth from the base and no leaves from the stems. I may prune those bare stems early since those (macs mostly) have been leafing out since early February. But I typically wait until mid May for that. A few shrubs in protected locations have had the broccoli going strong for a few weeks so they may bloom in 1-2 weeks. Way too early, I know, but last year was even earlier.

It has been a little dry this year in TX so, keep an eye on your shrubs' moisture since they were recently planted. Manually water them if necessary. Add water from the crown/base outwards and remember they probably do not have too many roots going far away from the stems yet. A gallon of water per watering when the soil feels dry to a depth of 4" should work fine (but use more water in the summer though)

Enjoy your ESs and TS. Luis

Thanks so much Luis you are always such a wealth of knowledge.