Gardenia is a high-maintenance beauty

QUESTION: I have an issue with a gardenia plant/tree that I purchased this summer. It was blooming nicely and looked to be very healthy, but when I brought it home I transplanted it out of the 3-gallon bucket to a larger pot and

Photo by Forest and Kim Starr

placed it on our porch, and it started to show a yellowing of the flowers and then stopped producing flowers. It was getting direct morning sun till about 10  a.m. and shade for the rest of the day. I moved the plant to the basement with no direct sun but plenty of light and much cooler temps. It still does not seem to be recovering. I water it every few days but careful not too water too much because the leaves turn brown if I do so. What do you suggest I do to revive this beautiful plant? – Rick

Gardenias are beautiful and their sweet fragrance is almost intoxicating, but they present a challenge
even in the best environment. I spent some time leafing through gardening books and looking around the Web for information, and it looks like you are experiencing a typical reaction to bringing a gardenia home. It sulks, and stops producing flowers.

Of course, a gardenia has a limited flowering season, typically spring into early summer, so it may be that yours was coming to the end of its flowering cycle when you brought it home. Plus, remember that gardenias grow better in the South’s lower regions, where winters don’t get as cold.

In our area, they should be treated as house plants, which means that you will have to bring it indoors or into a greenhouse and baby it through the winter or it will sulk some more. In the house, it becomes a magnet for mealybugs, mites and whiteflies.

So, if you still want to revive this temperamental beauty, here’s what it needs: acid soil, good drainage, full sun or partial shade, regular watering, high humidity, and nighttime temperatures of 50 – 55 degrees in winter and spring if you want flowers.

By the way, the most common gardenia, G. jasminoides (G. augusta), is said to be hardy to about 10 degrees, and may survive to zero degrees, but will likely die back to the roots. There are several varieties that may be hardier in colder climates: ‘Chuck Hayes,’ ‘Grif’s Select,’ and ‘Klein’s Hardy’ are
said to be slightly more tolerant of cold weather. Good luck.

*

Oh, deer: In many areas, deer come out frequently to sample the goodies they see growing around the house. Check out the list of deer-resistant plants in The Garden Club column in Saturday’s  Tennessean.

*

Two meetings at Cheekwood Tuesday night, Sept. 20, both open to the public:

The Perennial Plant Society will meet in Botanic Hall. Refreshments and plant swap begin at 6:30, and the meeting at 7  p.m. features guest speaker Kevin Guenter, president and owner of Design Resource and founder of The Sustainable Living Guild. He will speak on “Sustainable Patterns in the Garden.”

The Orchid Society of Middle Tennessee meets at 7 p.m. in Botanic Hall. Speaker is David Johnston of Jewell Orchids; his topic is “New Trends in Blue Cattleya.”

Fall — and aphids — in the air

QUESTION: Sometimes we see white, wooly-looking bugs in the air and all over the hackberry trees in the fall. At the same time, there is a black coating of something on everything under the trees. What is this?

These are Asian wooly hackberry aphids, which have been flying around Middle Tennessee for about a decade after making their way to the U.S. sometime in the mid-1990s. The aphid has a tiny mouth that resembles a beak, with which it pierces the leaves to extract the plant sugars. Then, like all aphids and
plant-sucking insects, they excrete a sweet, sticky waste product called honeydew, and in the heat of late summer, that substance grows sooty mold, the black substance you see on patio furniture, plants and anything else under a hackberry tree that is playing host to the insects.

I talked to U.T. Extension agent David Cook about the insects several years ago. He said that the feeding doesn’t cause serious damage to the tree. It’s considered mainly a nuisance pest.

If you feel the need to control the insects, Cook has suggested a systemic insecticide, applied around the tree’s root zone in the spring.

IF YOU THOUGHT last month seemed hotter than usual… you were right. Bobby Boyd at the National Weather Service sent me a list of factoids that made me sweat just to read them. Consider this:

August 2011 in Nashville was the 25^th hottest on record. There were 24 days when the temperature was 90 degrees or higher, and one day when it bubbled up to 102. That was August 3, and it broke the record for that date of 100 degrees, which was set in 1952.

The average temperature for August was 1.8 degrees above normal. The average high was 92; the average low was 68.9. Three of the 10 hottest summers in Nashville have occurred in the last five years.

All this makes these past few days of cooler weather even more welcome. Fall, ready or not, is in the air.

What else can go wrong with tomatoes?

QUESTION: My tomato plants are tall and full, and they have been blooming a lot but the blooms disappear. The flower usually dries up and falls off. Otherwise, they look  healthy. Can you tell me what’s wrong with them? – D.S.

When the weather is hot, tomato blossoms fall.

Two things could be causing tomato flowers to fall off: extreme heat and dry soil. When temperatures get above 90 degrees for several days – and we’ve had a lot of those days recently – tomato blossoms tend to drop off without setting fruit. Blossoms also drop off if the plants don’t get enough water. When the heat wave passes and if we finally get rain, you’ll probably see the tomatoes begin to bloom and set fruit again.

QUESTION: Some of my tomatoes look ripe but when I go to pick them they still have green patches that don’t ripen. – J.H.

I found information that suggests that the green patches on ripe tomatoes may be due to the tomatoes being on the interior of dense plants with heavy foliage. It’s a condition called “blotchy ripening.”

At the same Web site, which is CornellUniversity’s Vegetable MD Online, there are pictures of  tomatoes with catface, cracks, russeting, zippering and other common disorders. If you want to see just about anything that can go wrong in a tomato patch, find it here.

–

Cooler weather is coming soon, inviting you to get back out to the garden. Look for the September Landscape & Garden Calendar Saturday in The Tennessean.