Hello from Texas, Putri, and congratulations on your purchase. You did not mention the variety so I will assume that you purchased a mophead, a.k.a. as a French Hydrangea.

All hydrangeas will do well in a location where they get four hours of morning sun or less. Dappled sun under trees will also work. Full shade locations (like under some trees) will limit the number of blooms that the plants produces so do not choose location where the sun does not reach and where indirect sunlight from the other surfaces does not. Also, locate the plant label that comes with most plants and verify that the hydrangea can be planted in your climate zone.

In northern climates such as the Northeastern States, you can even plant hydrangeas in full sun but, in more southern locales like Texas and Florida, I would select a location where they get shade starting around 11am or they might suffer from sunscald. Some hot locations may actually be too hot for hydrangeas as they need also need to go dormant during winter months.

Note the estimated size of the plant at maturity and pick a spot where the plant will fit; you do not want to have to transplant it in later years and you definitely do not want to prune it every year either. Most mopheads will need about six feet.

Your location should have soil that drains well. Most hydrangeas will tolerate some clay in the soil but Oakleaf Hydrangeas will quickly suffer from root rot if allowed to get their feet wet for long periods of time (months).

The availability of moisture in the selected location is important. An overhang in your house may prevent rain from reaching the plant so make sure the soil can be kept moist, not wet. It is best to allow the soil to almost dry and then water. On a new plant, you may need to water it one gallon of water once/twice a week, depending on the temperatures. Watering slowly and deeply is best.

Because new plants suffer from wilting due to moisture issues, I suggest that you manually check the soil moisture daily by inserting a finger into the soil to a depth of 3-4 inches (7.5-10 cm). If it feels dry or almost dry then water; otherwise wait. Then observe how often you have to water (every 2/3/4 days and set your sprinkler to water 1 gallon of water on that schedule. When temperatures change by 10-15 degrees F and stay there, I manually check again to see if I need to water more. If the plant looks EXTREMELY wilted, give it some water immediately. But in most cases, try not to water a plant that is wilting if the soil feels wet; in most cases the plant will recover by bed time or next morning on its own. Wilting episodes start at the end of Spring and end in the Fall.

In northern climates, you can fertilize new shrubs with 1 cup of manure or cottonseed meal in June. Remove the mulch, water, spread the fertilizer and water again. Here in the South, I fertilize twice, in May and July. Keep the plant well mulched with 3-4 inches of acidic mulch up to the drip line; and maybe a little past that if you live in a hot location. You may not have to fertilize on your first year as most potted plants already contain slow-release fertilizers (can you notice some of those fertilizer colored balls in your pot?).

If your soil is not acidic, you may want to amend the soil in spring with aluminum sulfate or powdered Sulphur to prevent the leaves from developing iron chlorosis. Chelated iron products can also be used. Some plant nurseries sell a pH measuring kit that can help you determine the acidity of your soil. These kits are not accurate but should provide you with a good guesstimate. Kits that give you numbered results are better choices than others which just say that the soil is acid by color choices (it is hard to remember the exact hue of the color you had on prior tests). pH Levels between 5 and 7 are best. At approx. readings of 6.2, mopheads will begin to bloom blue flowers; above that they will bloom pink flowers.

You can also grow hydrangeas in pots too.

Does all that help you Putri?
Luis

yes i believe i have a mop head the color is blue. I transplanted the plant on my lawn and hopefully it'll thrive. by the way will fish emulsion do any good on hydrangeas?
thank u

As an occasional fertilizers, fish emulsion and liquid seaweed can be used. However, they do not provide the right amount of N-P-K minerals so, some manure, cottonseed meal or slow-release general chemical fertilizer would work best as "the" main fertilizer of choice in June.

PS - Putri, I forgot to mention that coffee grounds will also work. Not necessarily to acidify the soil (after boiling in water, they loose acidity) but because the leftover coffee grounds have some nitrogen.

Apply them once the danger of freezes has passed in spring and before July/August, when plants should be preparing to go dormant.

Putri, I'm sure you understand how your particular variety hydrangea blooms in the colors...pink ...and blue.
Pink, of course, is derived by the soil's being with a higher pH..(alkaline) and blue by its being acidic.

Normally you want to select the color you prefer--but your plant is a young thing and I think its not in the best interest of the plant to fool around with the soil trying to get a particular shade. Besides, allowing the first year at least, to show you how that pink might be something you like, you might stay away from adding anything to your soil until at least one year's growth. Keep your soil rather moisty ...not wet or soggy. See to its good drainage.

If you have other acid loving plants in the same vicinity as the hydrangea.....well then, that's different, by all means treat your soil so that the best color comes out.
But obtaining an acid soil unless it is already leaning in that direction (hydrangea likes it 4.5 to 6.5) is not an overnight happening. It may take many months--perhaps a season or two to give a proper pH.
You don't want to drastically change your soil to suit one plant. That could prove disastrous if you go too far.

The "macrophylla" mopheads are better not pruned at all rather than pruned badly. Let your plant grow and set it roots before thinking to cut it back any. Unless you plant is badly shaped and in need of cutting back, I'd leave it alone.

In your southern locale, summer heat can be very hard on plants. It is generally recommended for plants in the south to be given shade at its roots.
Whatever your sun conditions, do shade your roots by any number of means. For the hydrangea, you might think gravel or stones of size, wood such as a log...anything that can insulate the soil at the plant's roots.

Macs prefer a rich composty soil and if your soil is heavy do incorporate some humus rich compost, bark dust or aged manure. Leave a slight raise of the soil at the base so that it settles back without leaving any depression where water can puddle. A height of 1" or so is fine.

Your particular plant blooms on new shoots as well as old wood. For this reason you will have to see that this season's wood makes it through to spring. It is rather late to be concerned about that in your young plant but keep that in mind next late fall....it must be given protection so the wood of that season is the wood of the next season.

The mac prefers a welcoming shade...not direct sun..and not especially that hot afternoon sun of your locale.
If you have it in a sunny postion you will have to devise some way to give it shade.

If you are intent on trying to acidify your soil, then do read the label on packages or bottles of garden sulfur,aluminum sulfate or ammonium sulfate.
Thse are soil conditioners....not fertilizer, they treat the soil...not the plant.
Garden sulfur is a fungicide.

Lime is the opposite treatment for soils...it too is not a fertilizer but a soil conditioner. When you are unsure just how much, then treat the soil gradually so that harm doesn't make its ugly appearance overnight.
Water in your conditioners.