Are you sure the meter is right? What was the soil like before you tested it? What was the soil made of in general, like sand or clay? You can buy lime that is a powder forum at any good garden center, but I would not suggest over doing it, in case the meter is wrong. How does the rose look, is it suffering? What about buying a bag of rose planting mix instead?

I don't know for sure how accurate the meter is but the readings Ive taken generally make sense. Maybe ill buy a soil test kit to verify the accuracy of this unit. The soil seemed okay to me, it looked like pretty well drained soil and like I said I used Miracle grow potting soil mixed with some sand. The rose has only been in this location for about 5 days but so far it looks okay.

So your own soil is the correct PH for the rose. You added two acidic soil amendments.( MG potting mix is largely peat moss)

What was the rose growing in to start with ?

I would probably lift the rose and mix the amendments with the soil that's there better. Setting a plant in a "bowl" of whatever is not conductive to it adapting and growing out and down. Roses are tough, so it will probably be fine. Assuming your not having a heat wave, that is.

The rose was growing in a sunny area in the back of my yard but I had other plans for that area and decided to move it to the front. I didn't realize that potting soil was that acidic. The typical soil pH around my yard is probably closer to 6.0 except for the location of my blueberries.

I kind of doubted MG Potting Mix would have a pH that low, from the looks of what I have bought it does have shredded wood and compost and is not 100% peat moss. But peat moss can be around pH 4 so who knows. Scotts should have some specs for it, since it's probably produced at various plants and they want it to be consistent, but I could not find any on their website. They probably don't want you to know how simple it is to make. :-]

If the rose looks OK I would just add lime dust around the plant, scratch it in and water. Monitor pH and add more as required. If it's looking really bad and you just planted it, probably won't hurt to pull it up and amend the soil.

Since your pH is on the acid side everywhere in the yard, I would not use a lot of peat moss. It doesn't offer nutrients anyway, and the benefits of organic matter can be met with compost, which should have a neutral pH and nutrients as well.

Also, don't bother getting potting mix for in-ground plants. It's specifically designed for containers (particularly the particle size) and the extra expense is not necessary for the garden.

Where in the United States are you?
Those "soil test meters" are not known to be very reliable, but check it out with some vinegar (about pH 4.5 or so) and a baking soda solution (about 8.x or so). Best is a good reliable soil test from your state universities Cooperative Extension Service, if they do those.

Next time by a rose planting mix bag instead of the Miracle grow, I think miracle grow is mainly for house plants that would like that condition. But, if the rose is doing ok, you could still just add some rose mix to be certain, but if you dump a lot of lime on it, that could be bad and shock it.

Peat-based potting soils almost always have some sort of pH adjustment included with them - the intent is to have a potting mix that is nearly neutral to slightly acidic. I seriously doubt the mix would contribute to a pH reading that low. I'd be much more inclined to doubt the accuracy of the meter, specially one that is not a dedicated pH meter. Get a test kit from your local garden center and try that, using distilled water (NOT tap water).

btw, potting soil is not intended for garden usage. It is formulated specifically for containers and will possess characteristics which do not aid in inground plantings. And further, amending individual planting holes is a horticultural practice that is no longer encouraged. Plant roots are not supposed to remain confined to the original planting hole but spread out well beyond it. An enriched planting hole discourages this proper kind of root development. It also impacts good drainage in many soils. What comes out of eth planting hole goes back in - no additions. If you feel you need to use amendments, do so over the widest possible area or save them to use as a mulch or topdressing after planting.

This will sound rude, and it's not meant to be, but a pH of 4.0 is just bogus. I would toss that POS meter and rely on other signs.

Some areas of the East Coast could be close to 4.0, but mostly only in bogs, I think.

I doubt those meters are all that accurate. I have a $16 one that insisted a bag of PURE pine bark fines had a pH of 8.0. There is no way at all pine fines would be that high - they're almost as acidic as peat! Should be more like 5ish.

So the meters are junk. I'd get a REAL soil test.