You say you watered, but how much and how often? Did you mulch around them?

In sandy soil, you might need, especially while the gardenias are still getting established, to water 2-3 times a week. Since you want to soak the entire root area, long, slow watering is indicated. If you have been relying on a lawn irrigation system to get the job done, it probably isn't doing it. I would dig down around the roots, at least 6" deep, and see if it is moist or dry at that depth. If moist, then the problem most likely isn't water, but if, which I do think is more likely, it is dry down there, then you need to water, well and frequently, for at least another year. Water when the soil is dry, not on a schedule - stick a finger - or pointed piece of wood - down into the soil to the second knuckle/2" and see it it is wet or dry at that level. If dry, water; if moist, then wait, and check back later.

If you haven't mulched, do so - as widely as possible, no deeper than 4", and putting no mulch in the inch or so next to the trunks. Any good mulch will do - if there is grass where you want to put mulch, either carefully spray with weed-killer, or put down flattened cardboard or 4-6 overlapping sheets of black-ink newspaper - don't use landscape fabric or plastic under the mulch. The mulch will keep the roots cooler, and help whatever moisture is in the soil stay there longer, as well as limiting root competition from grasses and weeds. After you mulch, check under the mulch for soil moisture before watering.

Thanks. I watered every day when they were first planted. Then held off some. We had rain Tues. night, so I didn't water yesterday. They still look bad. Should I add some iron? Somebody mentioned that in another post.
Thanks

Iron chlorosis causes paling of the leaves, with the veins staying green(er) for longer. If the leaves on your gardenias aren't doing that, but are paling uniformly, turning yellow and falling off, then iron won't help and might hurt.

Since it has been pretty hot lately, at least for me, it may be that it's just too sunny where they are for them as newly planted babies. I would water a bit more often, checking to see how dry or moist the soil is before you water. Since all 4 seem to be struggling, I would be much more inclined to think that it is a moisture problem, rather than a disease or deficiency.

Even if it rained, you don't say how much it rained. Unless it was at least half an inch, and that on already somewhat damp soil, that's not going to get the water down among the roots where it is needed. Only if it rained an inch or more, or has been raining every few days, is less than an inch of rain at a time enough for you to not check and water as needed. What did your digging down to check at the root level tell you about the present moisture levels?

Trailing gardenia is Radicans.
They only like morning sun.
Are they in sun in the hot afternoon?
In the spring, they may tolerate the cooler days in the sun.
They are sun sensitiive and can't take any more than morning sun for about 3-4 hours.
After that, they need bright light for the rest of the day.
You also stated that you have amended the soil.
What did you amend the soil with?
You didn't state that.
ALso, check the bark and leavs for white powdery looking substance.
My radicans, or trailing gardenia had the worst case of this and the plant was having the same symptoms as yours.
Man, that powdery mildew is hard to handle too.
GOod luck with your gardenia!

dibbit and butterfly -
Thanks for the suggestions. I checked the moisture level and found the soil moist down about 6 inches. As far as the sunlight - they do get afternoon sun, but are planted under some pine trees that filter it somewhat. It may be too hot there, don't know. However, the two that seem to be doing a little better are actually out on the edge of the bed where they get more sun than the others (?) I have not seen any sign of mildew or whiteflies. We have had rain here twice this week so I have not watered. As far as amending the soil, I put some black cow in when I planted them and watered with miracle grow once after planting.
By the way, when I have seen whiteflies on other plants in the past, they are very visible and fly off when you shake the foliage, that is how I have been checking for them on the gardenias and have not seen this. Am I correct or could they be there and I'm just not seeing them.
Thanks

Ben,
by stating you fertilized with Miracle Grow right after planting, (which by the way is a no no- don't fertilize a plant that is under stress), are referring to Miracid?
They are 2 different formulas.
Don't fertilize with anything else til they start to look healthier.
Gardenia basics-
Water- doesn't seem to be a problem if it is moist 6 inches down. Did you mulch on top? Are they planted directly under a pine tree in the ground? Are they raised up? in a mound under the pine tree? Are they sitting directly on top of the pine tree roots competing for water and food?
Sun- they can't take hot afternoon sun at all. Put your hands where they are sitting and see if you feel the sun on your hands, if you do, you must move them or shade them somehow.
Soil, It seems to me, I am not familiar with sandy soil, that you did the right thing with your soil. The pine needles aren't going to hurt the situation either, good for mulch for gardenia.
I am sorry that I can't figure it out for you.
Radicans are my favorite gardenias, their foilage is so dark and beautiful.
I hope they pull through for you.

I lost two August Beauty Gardenias this summer. Both planted in the spring in good soil, average water, no fertilizer. It started with the base, the leaves turned yellow. Eventually, the plant was putting out new growth, but losing leaves faster. Neither bloomed. I pulled the last one out on Monday.

I have to disagree and say that radicans can definitely take afternoon sun in these parts. Mne gets sun from about 2-5 or so and has been happy as a clam for about 14 years now. I have neighbors down the road who have them in full blazing sun and they do ok. I also have one i planted in my fair plot this summer and it gets afternoon sun- about 12-3 or so and it's doing ok. If the plants in ben's case are doing better in more sun, i'd say leave them do their thing. Take cues from the plants on your site, not someone far away. Normally things take less sun down here than in PA, but that's just my observances, and backwards in this case according to what he's seen. I like the fragrance of radicans better than the taller varieties myself.

Also, i put in a very heavily variegated tall gardenia last fall that i lost this summer as well. Granted, we've been droughty and i haven't been after it all that much with the water, but i believe it had enough. I'll try to replant when we are getting more regular rain. It was in a fairly shaded spot as i was told by the seller that's what it needed and wanted to do well. The foliage does better in those conditions, but the bush won't flower as much. The foliage on that variety was so pretty i didn't care as much about the flowers.

Don't you folks know that gardenias need acidic soil. That's why the leaves yellow. Put a little epsom salt in the palm of your hand. Dig up the soil about a foot from the plant and spread it out in the ground. Also put coffee grounds spread out in the ground. Cover back the soil and water. You will see a difference in 8 hours? When you plant, you should untangle the roots.

My gardenia perked up within 8 hours!

I killed 5 gardenia (August Beauty) that we planted in our side yard when we moved in. I think it was a combination of factors but I believe the worst thing that I did to them was offer them no protection from the sun. I purchased them at the farmers market and they were represented to me as full sun plants that would fit my situation. I did feed them miracid from time to time and water them when it seemed dry. However they immediately yellowed although the leaves clung on for over a year they just looked worse and worse. When I pruned them to see if they would grow more stems (a book recommended this) they never grew back at all. I was glad to stop looking at them at this point. The neighbors I see successfully growing them have planted them in partly or mostly shaded locations. Maybe it helps to have them near a foundation of a house and out of the wind too. Now I try to be a more sophisticated shopper.