In all these years, I've never done preventive pesticide treatments and I have never pruned anything! Except for a year that I had to decimate it for being infested with aphids all summer that have all malformed leaves growth in that period. The next year I have drunk it of "Confidor" (a systemic pesticide).
This year, no nothing!
If the plant is generally in good health, leaf texture, gloss of the same, etc. .--- do NOT worry for a few yellow leaves or a few brown leaves or the loss of some leaf: it�s a natural replacement of old leaves, normal, especially in spring.
The action of insecticide and fungicide should be performed only after ascertaining the cause and intervene only when needed and never in advance. When there is a fine persistent rain let�s take it all. The soil will get rid of the salts accumulated during cultivation.
When to replace the pot
1 - The first sign that the plant sends us is the more frequent watering.
2 - The second signal that it tells us when it appears to be running out a "permanent" iron chlorosis and the new leaves appear "small".
3 � We have lots of "distorted" buds growing. In this case they will open all the same, but it causes several of them to dry (this happens even when the plant bears a lot of them, because it hasn�t the strength to take them to flowering).
4 - Another thing that determines that it�s time to change the pot is NOT issuing new growth on the branches at the nodes where the leaves have fallen for the natural turnover.

If the plant has chlorotic leaves on the leaves of last year use iron Sequestrene, is more direct in addressing the issue, within three weeks you will have the green leaves. If, however, is the natural replacement of the leaves, which takes place this season, the leaves are usually more clear.

The gardenias aging tend to produce twigs scantily dressed with smaller leaves and become susceptible to the coupler cochineal / sooty mold. The remedy is a drastic rejuvenation: in late winter (March), take out the plant from its pot and greatly reduce the roots by removing about 5 cm. of soil on all the perimeter of the entire root ball, trying to free the roots from the old soil, do not worry if you break the roots, do it with your hands because that way is simpler and faster, nothing dangerous happens. It is very important, to avoid problems in a successful repotting to expose more roots as possible: in this way, once repotted, the gardenia roots will find new soil and will start immediately. It is essential to treat the plant well, leave it to settle and, at the appearance of new growth, begin a proper fertilization plan.
At the same time the plant is cut back drastically and without fear then repot it in a new acidic soil plus, depending on the size of the pot, one or two or three handfuls of manure at the bottom plus a good drainage layer at the bottom. In a year the plant will resume great.

Is it okay to start with beef blood but no more than two or three times, because using it more helps the vegetation at the expense of flowering and homogeneous growth.
After repotting from the bare branches will sprout new growth, you will lose the first flowering, but if you hurry you�ll have the one before it goes dormant.

To make it grow more compact, cut over a couple of leaves below the withered flower. The withered flower is cut at the base, near the branch, thus doubling the branch, so after it you�ll have two branches that grow in width instead of one.
The cut must be done perpendicular to the branch so that the cut surface is smaller and heals more quickly with less risk of fungi or bacteria infection.

The loss of buds in a winter housed plant is a normal thing thanks to the warmth: the heat would be good but the light isn�t enough, so the plant cannot keep up the buds.
According to the plant strength, it has buds or causes them to fall throughout the year.
Pruning of Gardenia jasminoides
It is a plant that doesn�t need pruning: when removing the whitered flowers the plant doubles the branch.
With the right fertilization the plant does not empty or becomes straggly (it keeps being bushy) even after many years of cultivation in pots.
Of course it needs to be well nourished so that it can carry on * all * of the vegetation and doesn�t not have to let go buds or leaves.

Propagation.
just cut an apex, remove the leaves along the branch to be buried directly in soil for acid-loving plants. Water thoroughly, cover the cuttings with a well placed in the ground half cut plastic bottle.
Better to use the part with the cap, because if it creates too much condensation inside the bottle, opening the cap it decreases, and it can be close after it.
Occasionally check that the substrate is not too dry. In this case water it again.
By following these few rules cuttings root quickly.
So easy that I have done it several times in winter, take cuttings, prepared as above, at home in a good light and let it take care of itself.

Chlorosis If the plant is subject to it, no point in using Sequestrene, the plant is telling you that the soil is depleted and must be replaced almost completely. By doing so for several years you will never see more chlorosis on the plant just watered with tap water, until the next soil exhaustion.>
This is the link (with pics) of the author of the directions above.
http://freeforumzone.leonardo.it/lofi/Gardenia-jasminoides/D5118047.ht ml