It's not too late, but it IS time to get at it!

Gardenias are one of the easiest plants to propagate, but I remember how it felt to be told "easy" when I was just starting out. So, here it is step by step. (Forgive me if this is more than you wanted.) It's true that you can root gardenia cuttings in water. And it's also true that you can do it without the rubbermaid box that I describe. But this is the easiest, most foolproof way that I have found.

1 Fill some pots with potting soil, packing the soil in firmly. (I like about a quart pot that's not too big in diameter, but is as deep as possible. This gives you a good root run without taking up too much space or soil at first.)
2 Take a skewer or ice pick and "drill" a hole into the soil in the center of the pots.
3. Take cuttings from your bush. Cut from the tips of branches with nice healthy looking leaves. You want each cutting to have at least 2 or 3 sets of leaves on it. It is perfectly okay to take a long cutting from one branch and then cut it into the three leave sections. Just be sure to keep track of the bottom and top of each section. The bottom must always go into the soil, the top must always point toward the sun.
4. Cut the bottom set/s of leaves off the stem cutting, leaving one or two sets of leaves at the top
5. Stick the cutting into the hole you drilled, stopping when the top leaves are resting just on top of the soil.
6 Water. Water. Water, until you see water coming out the drain holes of the pot.
7. Let the pots drain until there's no more coming out of the bottom: about 10 minutes usually. (This is VERY important.)
8. Place your pots of cuttings on top of the lid of a Rubbermaid storage container (clear plastic).
9. Turn the box part upside down and place it over the pots, forming a dome.

10. You should see humidity begin to collect on the inside of the dome almost immediately. Put the whole "mini greenhouse" in the shade (a porch is perfect). Leave the lid in place, although it's quite alright to peek occasionally until your cuttings are rooted. With Gardenias this can be as soon as 10 days to 2 weeks. You won't have to water or anything while your plants are under the dome.
11. Remove the dome when you see new leaves beginning to form on the tops of your cuttings. Then water and fertilize as you would any potted plant.
12. When you see roots starting to come out the bottom of your pots, pot the plants up into bigger containers. (1 gallon if you are going to leave it in the pot for a year or less. 3 gallon pot if you're going to grow it longer.)
13. I would recommend that you keep your plants in pots through the first winter, just because they're so small, that you could lose some of them. But if that's not an option, put them into very well prepared soil this fall as the temperatures begin to fall. Most of them will make it.