Native Plants
Q. Who is Mr. Smarty Plants?
A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.
Did you know you can access the Native Plant Information Network with your web-enabled smartphone?
Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.
rate this answer
Sunday - August 17, 2008
From: McAlester, OK
Region: Southwest
Topic: Non-Natives, Compost and Mulch, Diseases and Disorders, Shrubs
Title: Failure to bloom of non-native Althea in Oklahoma
Answered by: Barbara Medford
QUESTION:
I have 2 Althea bushes that will not bloom. For the past 2 years, they become covered in buds, which eventually yellow, but never open. The buds are fully developed. This year the branches have started to bow down, but the leaves appear healthy. They are about 3-4 years old. They are in full sun till 3-4 pm and are watered twice a week. What do these bushes need?ANSWER:
The althea is also called Rose of Sharon, scientific name Hibiscus syriacus. It is a mallow, a member of the Malvaceae family, and native to China and India. At the Lady Bird Johnson Wildflower Center, we are focused on the use of plants native to North America and to the area in which they are being grown. So, this plant falls out of our area of expertise. However, we will see if we can find some information for you on the failure of the blooms on your bushes to open.
Among the things we learned about your plant is that the blooms last just one day, they open in the morning, close in the evening and the closed bud remains on the bush for a while until it drops off. They require ample moisture to flower best and avoid leaf drop. This has been such a hot, dry summer that might be a clue to the problem. However, you say they are 3-4 years old. Did the blooms on the plant ever open? Another thing, bud drop can be caused by too much or too little water or over-fertilization.
So, with these pieces of information, but no real answer to your problem, we are going to make some recommendations in the culture of your plants, and see if that helps. These are not an immediate fix, but over time could help. First, blooms are on new wood, so the plant needs regular pruning. It probably is too late in the blooming season for pruning to do any good for this year. But, when the weather cools off, give the bushes a good haircut.
Second, make sure that the blooms are really not opening at all. Is there any possibility that you only have time to go out in your garden in the evening, by which time the blooms have already closed? For now, stop fertilizing. You may have been over-fertilizing with a high nitrogen fertilizer, which will cause lush green leaves but not blooms. Next summer, about 6 weeks before the time that your bushes have tried to bloom in the past, put a fertilizer on them with a higher phosphate content, the middle number on fertilizer designations. This encourages bloom. Read the instructions on the package to determine how much and how often.
Now, let's address the water issue. We don't know what kind of soil you have, but are betting it's some version of an alkaline clay. Which is probably fine for the Hibiscus syriacus, but it can affect the way the plant gets water. About every other day, stick a hose down in the dirt around the roots and let a slow dribble go in until the water shows up on the surface. If the water stays on the surface more than about a half hour, you have poor drainage. Water can collect around the roots and just sit there. If that is the case, water them less but more frequently. This will be trial and error to see how well the drainage is working. If you can, try to work some organic materials, like compost, into the soil around the roots. This will improve the texture of the soil and definitely improve drainage. And mulch them all with a shredded bark mulch. This will not only help hold in the moisture and protect the plant from heat and cold but, as the mulch decomposes, will add more to the organic content of the soil.
This USDA Forest Service website on Hibiscus syriacus goes into more detail on the matters discussed above, and also mentions a possible blight on the blooms caused by a fungus. It doesn't say what should be done about that, but it would probably be better to try some of the other fixes first before you buy an anti-fungal spray. This site also notes that the plants could use some protection from afternoon sun, and you indicate that they are in full sun until 3 to 4 pm. You probably are not interested in moving them just on that account, but there again, the mulch and additional watering should help the bushes do better.
More Diseases and Disorders Questions
Care for California lilacs from Portland OR
January 16, 2014 - Hi There,
We live in the Portland Oregon area, so temps are moderate and winters are wet. We have several California Lilacs that are about 7ft in height and have created the perfect screen. Love th...
view the full question and answer
Oak trees shedding leaves in Denton TX
May 27, 2012 - In Denton, TX we have two mature Quercus buckleyi. It is May 11th 2012 and one of these trees has been shedding green leaves for the last week. The only changes we have made are: planted English ivy...
view the full question and answer
Rust on Blackberry
April 17, 2015 - I have two new blackberry bushes that I planted fall 2014. Only weeks after I planted the plant began to have rust color balls under the leaves then leaves began to die and fall off. When I returned t...
view the full question and answer
Problem with American Beautyberry in Houston.
July 02, 2014 - My American Beautyberry is dying one branch at a time. The entire plant looks great, now flowering and starting to put out berries. Then one or two branches will completely die. Trim those off, wi...
view the full question and answer
Mountain Laurel having trouble in AZ
June 07, 2011 - A Sophora secundflora (Texas mountain laurel) was planted to an Arizona north faced front yard last year in August under full sun. Starting early this year, I noticed its leaves turn to light green an...
view the full question and answer
Support the Wildflower Center by Donating Online or Becoming a Member today. |