Gardenias

Gardenia jasminoides 'Mystery'

Gardenia jasminoides ‘Mystery’

Q. I’m the caretaker of an apartment building and I do our little flower garden.
Way over 10 years ago I planted two gardenia plants together. I didn’t think they would even grow. Well, you should see my bush now!
I have over a hundred flowers sometimes. I would like to know if I should cut it back as it’s getting pretty big and heavy.
– Annette Vaseloff, Van Nuys
A. After reading the above, I must admit that I had my doubts as to the veracity of the writer’s claim.
In more than 30 years of plant watching in the Valley, I had never seen a gardenia with a hundred flowers. More often than not, the gardenias I had seen were struggling plants that appeared to flower with great difficulty, mere survival appearing to be their main purpose in living.
I had to take a look for myself and went to visit Vaseloff’s gardenia. As it turned out, she had erred greatly in her flower count, but on the conservative side. The number of flowers, together with fat flower buds ready to open, number several hundred at least.
In the Valley, gardenias, due to the powerful fragrance of their blooms, are among the most frequently purchased plants, despite their high rate of failure. Their downfall is alkaline soil. Valley soil, like that throughout Southern California and the southwestern U.S., tends to be on the alkaline side of the pH scale.
Gardenias are native to tropical China, Africa and Oceania where, due to heavy rainfall, alkaline compounds are leached out of the soil, making it acidic.
You can acidify Valley soil by adding peat moss, iron sulfate or gypsum to it during planting, by using fertilizer that is formulated specifically for acid-loving plants, and by continual applications of compost. The breakdown of compost, in releasing humic acid, has an acidifying affect on the soil.
Regardless of the pH, your soil must be fast-draining if gardenias are to have a fair chance of feeling comfortable in it. If your soil is compacted, mix in topsoil, sold in nurseries by the bag, whose primary constituent is sand. Adding compost will also improve soil drainage.
Much to my surprise, Vaseloff’s gardenia was growing in a south-
facing exposure. The healthiest gardenias I had seen locally received either morning or filtered sun, such as that provided in a narrow side yard between two houses, and still had their fair share of yellowing, chlorotic leaves.
The success of Vaseloff’s gardenia, like that of most plants, may ultimately be explained by its microclimate, especially where its roots are concerned. The bushiness of this gardenia means that its roots are always shaded and cool.
Like many tropical plants, gardenias grow best with their heads in the sun and their feet in the shade. In addition, Vaseloff’s plant is growing behind a low wall, which also protects its roots from the elements, and in front of a concrete patio. Patios keep moisture trapped underneath, benefiting adjacent plants.
Finally, the surrounding hardscape prevents people from treading on and compacting the soil and makes soil cultivation, and the root damage it causes, impossible.
As I told Vaseloff, gardenia shrubs should be minimally pruned, allowing them to reach their mature height and girth of 4 to 5 feet for maximum bloom. With a gardenia, the only pruning required is removal of dead stems and trimming back shoots that go outside the natural shape of the plant.
Vaseloff’s gardenia is a Veitchii (VETCH-ee-eye) cultivar. Although its flowers are half the size of those on the Mystery gardenia, Veitchii produces significantly more flowers and over a much longer bloom season than Mystery.
During the summer, Vaseloff waters her gardenia about once every three days and fertilizes it occasionally with Miracle-Gro.

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