I.Cl.S. - Collecting and Growing Clematis Seeds

It is the right time of year in the Northern Hemisphere to be collecting Clematis Seeds and we have had a number of queries recently. Many of you are keen to have a go at growing your own so we hope that this page will help.

Identifying Viable Seeds

Clematis seed head

Any seed you collect needs to be 'viable', that is it has the potential to germinate. Generally viable seed will be visible in the seedhead, this is particularly true of species. If you can't see any seeds, however small, then probably none have set and so there is nothing to germinate.

With some varieties you'll find only a few of the seeds in the seedhead are viable and so you'll only be able to see a few seeds. But for all varieties, wait until the seeds go brown before you collect them as this is the most common indication they've ripened and dried and can be safely stored.

It is easy to identify seeds in large flowered hybrids as they have large 'heads'. Hybrid seed probably won't grow true to form, often producing a plant which is reluctant to flower at all. However this is how many new clematis are produced, though breeders go to great lengths to make sure they know exactly the parentage of all of their seedlings.

The picture above shows Clematis heracleifolia with some seeds that have 'set' and others that have not. Remember if you are collecting seeds, the I.Cl.S. Seed Exchange would love to receive some, please see below for details.

Fiona Woolfenden, Great Britain.

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Germinating Clematis from Seeds

Clematis seeds may take up to three years to germinate, but you should get some germination in about six months to a year. Collect ripe seed in the fall and plant in sterile seed starting mix, covering seeds with a thin layer of sand. Place the container into a zip lock polyethylene bag and place it outside in a shady spot (or a refrigerator) for several months during the winter so that they go through several freeze/thaw cycles.

Then place the covered container in a warm location out of direct sunlight and wait for your first seedling. As the seeds germinate, the small plants should be pricked out of the germinating container and planted into a small pot using a sterile soilless mix. Be very careful as the root will be a single long root in the beginning. As it grows larger it will need a larger pot, fertilizer and constant moisture. When the plant has three sets of leaves, pinch out the growing tip to promote branching.

Seeds collected from hybrid clematis will usually not breed true to the parent so you might create a new and exciting cultivar that may be named after yourself or a loved one. The chances of getting a new winner are about one in 200, but acceptable smaller flowers of little commercial value will result. They make great gifts to fellow gardeners if you get too many.

Your seedling will take at least a year to offer its first bloom and another three years to become a mature plant. I usually wait until it blooms before planting it out in the garden. A greenhouse helps. It is a labor of love! Good luck!

Bill Bird, USA.

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The Society's Seed Exchange

The seed exchange is a vital part of our Society and one of the main benefits for Members who live all over the world. The seed exchange enables Members from different parts of the world an opportunity to obtain seed of Clematis plants which is difficult to find in their own countries.

The 2021 Seed Exchange List, comprising seed collected during 2020 along with some seed collected and remaining from 2019, is now available. It is available on this website, please click 2021 Seed Exchange List. Seed can be requested by any International Clematis Society member and is provided free, subject to availability. Instructions on how to request seeds are contained in the seedlist. Note, one year old seed should be just as viable as seed collected much more recently.

Instructions on donating seed to the Seed Exchange

The best seed to donate to the Seed Exchange is from species as these are most likely to germinate true to type. Seed collected in the wild, specially from expeditions, is much appreciated by other members. Varieties common in one country are often difficult to find in another.

The seeds that you donate to the Seed Exchange should be 'viable', generally the seed in the head will be visible, particularly with species. If it is not then the seed has probably not 'set' and will not germinate. On a number of varieties you find one or two seeds are viable and the rest are not. The seeds should be well ripened and dry, this usually means that the seed head will be brown.

We would appreciate if you can put the dry seeds in a paper envelope and mark the outside with the name of the Clematis species or hybrid that you picked them from. If you collected them in the wild please add the name of the place that they were collected from.

The Seed Exchange Administrator is Benedikt Herian who lives in Germany. All members have received a Society newsletter giving details of where to send their seed, but if you have mislaid this, or have any other related question you can get in touch with Benedikt. To protect Benedikt's personal email address please email:

If you believe that you will be able to donate some seed but that it is not yet ripe, please contact Benedikt and let him know. The seeds are collected this year and early next year the Society will send its Members a list of the seeds available. Seeds are free to Members but we ask that if you would like to donate some money towards the running of the Seed Exchange that you add a little extra to your Membership Fee.

However please note, new regulations are due to be introduced on 14th December 2019 which would require a phytosanitary certificate to accompany seed sent into the EU from an outside (non-EU) location. To be on the safe side, please send in seed to arrive before this date.

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@ K.Woolfenden

All information contained at this site is personal to Ken Woolfenden and
does not represent the official view of the International Clematis Society.