How to harvest hollyhock seeds – to grow more summer flowers for free

Q: I have grown hollyhocks along a backyard fence this summer and they are blooming beautifully. I'd like to save the seeds for sowing new plants – what's the best way to do this?

A: Collecting seeds is a fun and low-cost way to grow a fresh batch of flowers. And with hollyhocks, it's simple, as the robust seed pods are easy to handle.

There are just a few things to bear in mind, such as harvesting the seeds at the right time and storing them correctly if you don't plan to sow them straight away. Below, the experts explain how to go about this rewarding task for more of these cottage garden favorites.

How to save hollyhock seeds for sowing new plants

Hold back the temptation to deadhead these tall flowering plants and they'll produce a generous supply of seeds. 

Left alone, these seeds will eventually fall and self-sow. By collecting them instead, you can control where new plants will pop up – perhaps you want to grow some along a front yard wall, for instance.

When to harvest hollyhock seeds

Anna Ohler, the owner of Bright Lane Gardens nursery, says, 'After the flowers have bloomed and faded, hollyhocks produce seed pods that start off green and gradually turn brown as they mature. 

'You should wait until these pods are fully dry and brown, which usually occurs in late summer to early fall,' she continues. 'At this point, the seeds inside will be black or dark brown, indicating they are ready for harvesting.'

Seeds can be collected from many other summer flowers around this time of year, too, including coneflowers and marigolds.

Anna Ohler

Anna is an avid plant hobbyist and the owner and operator of Bright Lane Gardens, a boutique plant nursery in Northern Michigan. With over a decade of experience in gardening and landscaping, she takes every opportunity to share her knowledge on all things plant-related. She also runs the company's YouTube channel, which is full of practical advice.

How to harvest hollyhock seeds

Meredith Bishop of Bloom & Bounty recommends using pruners to clip the seed pods off into a brown paper bag, or you can remove them by hand. 'As with harvesting all seeds, wait for a dry day to harvest, or fungus may develop on the seeds,' she adds.

Brock Ingham of Bigger Garden advises keeping the bag in a warm, dry spot with good airflow for about a week or two, so the seeds can continue drying out. 'After that, gently break open the seed pods to release the seeds,' he continues. Pick out the chaff and lay them out on a paper towel for a few more days to ensure they're completely dry before storage.

Meredith Bishop

Meredith Bishop is an heirloom cut-flower grower in urban Nashville, TN. She operates a design studio called Bloom & Bounty with her organically-grown flowers, and enjoys writing, speaking, and leading all manner of gardening workshops.

Brock Ingham

Brock is an experienced gardener who is studying to become a horticultural expert. With over a decade of experience, he has become gifted at growing a variety of unique and rare plants. He's also a strong advocate for farmers and knows that behind every crop, there's a farmer with a story to tell.

How should you store harvested hollyhock seeds?

Janice Cox, a National Garden Bureau member and author of Natural Beauty from the Garden (from Ogden Publications), recommends packaging the dried seeds into small paper envelopes or glass jars. 'Make sure to label your jars and packages with any details you would like to remember,' she adds. 'I usually note color and bloom shapes.' Brock says, 'It’s best to avoid plastic bags unless the seeds are absolutely dry, since plastic can trap moisture and lead to mold.' 

These paper seed envelopes from Amazon should do the job nicely, and you get 100 in a pack.

Hollyhock seeds then need a chilling period, as Meredith points out. Sowing hollyhock seeds in the fall allows them to chill naturally over winter. But, if you want to store them, she recommends keeping them in a refrigerator or freezer.

Meredith also highlights how they should be kept dark and dry – the opposite conditions that seeds need to germinate. 'For seeds that I save in the freezer, I add a desiccant to the envelope or bag to ensure any escaped moisture does not enter the seeds,' she adds. We like the look of these well-rated silica gel packs from Amazon.

Top tip: Note that harvested seeds may not produce plants that are the exact same as the parent plant. However, different variations can be just as beautiful.

Brock says, 'Properly stored, hollyhock seeds can stay viable for up to three years, but they’re most reliable when used within a year or two.'

It's worth noting that hollyhock seeds are biennials, which means they will put on leafy growth in their first year after sowing, and then bloom in the second year. Because of this, Janice recommends sowing the seeds every year. That way, you'll always have a summertime show.

Looking for more advice on collecting seeds from your favorite blooms? Our guides on how to save hibiscus seeds and collecting lavender seeds are well worth a look.