Knowledgebase

Hollyhocks Not Blooming #850627

Asked September 20, 2023, 12:29 PM EDT

Hello.  I have a grove of hollyhocks that only partially bloom each year.  The plants produce many flower buds but only the top 1-2 buds per stalk actually produce a  flower.  All the other buds turn brown, dry up, and do not bloom.  I was wondering what I should do next year to reduce or eliminate the flower buds from not blooming and turning brown.  Fertilizer, watering, soil, etc.  It would be a pretty grove of flowers if I can figure out how to get all of the buds to flower.  I have attached a photo example of the brown buds that is typical to what I am finding.

Thank you.

Warner

Boulder County Colorado

Expert Response

Hi Warner,

Thank you for you email and the picture of your hollyhocks. While hollyhocks are a water-wise choice for landscaping, they can be susceptible to rust (fungus) and weevils. They prefer a site that gets at least 6 hours of sun a day and fertile, well-drained soil. They do not thrive in clay. If you would like a definitive diagnosis of the problem, we will need a sample to look at under a microscope. 

General care:
  • Hollyhocks are biennial and bloom the second growing season. They typically have a 2-3 yr lifespan.
  • Remove any diseased or dying leaves promptly.
  • Cut back the stalk to a couple inches from the base after blooming. You may get a 2nd bloom.
  • Water from below, and do not overwater. (Our especially wet spring has produced many "new" problems for Colorado gardeners including fungal disease.)
  • Make sure there is sufficient airflow among stalks. You may need to thin.
  • If soil has low fertility, add organic matter (compost) when planting or a liquid fertilizer during the growing season. Use according to package directions.
This Plant Talk addresses hollyhock rust and how to treat. This flyer on the hollyhock weevil has pictures of the insect and how it affects the plant. Whether you decide to use a fungicide to treat rust or an insecticide for the weevil, please follow all instructions on the label and use only as directed.

If you would like to drop off a sample at the Boulder County Extension Office in Longmont, here is information. The address is 9595 Nelson Rd, Longmont, on the south side of the Boulder County Fairgrounds.  Instructions for collecting and packaging the sample are here. 
Best,

CSU Extension Boulder County Master Gardeners


Please take a moment to complete the following confidential survey in order to ensure our continued ability to serve the public.

https://www.surveymonkey.com/r/HorticultureREGDATA



An Ask Extension Expert Replied September 20, 2023, 9:53 PM EDT

Loading ...