Q: I adore hollyhocks for their vibrant, crinkled blooms, and I've cultivated a row alongside my patio from seeds. Sadly, last year, I noticed unsightly orange and yellow pustules on the upper leaves, with dark spots underneath. The leaves eventually dried out and fell off. What caused this, and how can I stop it from recurring?
A: The symptoms you're observing are classic signs of hollyhock rust, a prevalent disease stemming from the fungus Puccinia malvacearum. This fungus can also infect other plants in the mallow family, like hibiscus.
"It typically starts at the base of the plant and moves upward, also affecting the stems," explains a gardening expert. As you noticed, severely impacted hollyhocks may lose their leaves and struggle to flourish. Fortunately, there are effective strategies to minimize the risk.
With over 50 years in gardening journalism, this expert frequently addresses reader inquiries in Amateur Gardening magazine, authored four horticulture books, and has delivered numerous talks on the subject.
Hollyhocks beautifully enhance flower beds and borders
3 Strategies to Prevent Hollyhock Rust
Maintain the health of these stunning plants with the following tips.
1. Remove Plants After Blooming
The fungus responsible for hollyhock rust survives the winter on infected leaves and debris, releasing spores come spring, according to a gardening expert.
Even if plants appear healthy during their first growing season, they may develop rust in the following year. Therefore, many gardeners opt to discard all plant remnants post-bloom. Fresh seeds can then be sown in a new location – consider the beautiful 'Chaters Pink' hollyhock variety from Burpee for vibrant additions to your flower beds. "Proper moisture-retentive soil and adequate air circulation give plants the best chance of thriving," the expert advises.
If you prefer to keep your hollyhocks for another season, cutting them back to soil level in the fall can help reduce disease risks. Be sure to dispose of the trimmings rather than composting them, as recommended.
This expert trained at Kew Gardens and has worked in various horticultural roles since 1986, contributing to Amateur Gardening magazine and serving on BBC Radio 4's Gardeners' Question Time panel for 27 years.
Rust appears as orange pustules on leaves
2. Regularly Check Plants and Remove Affected Areas
It's crucial to frequently inspect hollyhocks for any early signs of rust and promptly remove any infected leaves. Always clean your pruning tools afterward to prevent spreading the disease.
If you're buying potted plants from a nursery, inspect them for any signs of rust, as a single infected plant can contaminate your other hollyhocks.
3. Use a Fungicide
Applying a fungicide, like BioAdvanced Disease Control for Roses, Flowers and Shrubs available on Amazon, can help manage the disease.
"Treat plants before rust appears and continue applications throughout the growth season," the expert recommends. These products are also effective against rose black spot.
Fungicides can help mitigate the risk of rust on hollyhocks
Common Questions
Are there rust-resistant hollyhock varieties?
'The attractive bicolored Halo Series is noted for its rust resistance and is worth trying,' the expert states. The 'Happy Lights Hollyhock Mix' is also said to have a lower susceptibility to this disease.
What's the method of spread for hollyhock rust?
Spores are released from pustules and disperse through air currents, often appearing unexpectedly, even in areas without previous hollyhock growth. However, wild mallows can also be a source, so eliminating any mallow weeds can help control the spread.
These charming garden plants are certainly worth nurturing for their stunning blooms, so don't let rust deter you. For an easy fix, simply replace them after their summer display – it's an affordable and straightforward way to grow these flowers from seed.
