How do I collect seeds from my geraniums so that I can start them in my greenhouse next year?
Your question doesn't say whether you're trying to collect seeds from hardy geraniums (Cranesbill) or the non-hardy variety (Pelargonium), but I'll assume you're talking about the non-hardy variety since that's what most people mean when they refer to geraniums.
Most information about the propagation of geraniums focuses on cuttings and there is a very good reason for that. It is far easier to propagate geraniums via cuttings than by starting them from seeds. That doesn't mean you won’t be successful going the seed route, it just means that once I finish outlining the requirements, you may join the hordes of gardeners who've decided that it isn't worth the effort.
The first thing you need to know before attempting to collect seeds is that most geraniums are hybrids and any new plants started from the seeds of hybridized plants tend not to come out true-to-type, assuming they germinate at all. The flowers you get may look like the ones you grew this year or they may share characteristics with one or both of the parent plants - and not necessarily the most desirable characteristics.
That's assuming the seeds are viable at all and they may not be. It's not uncommon for hybridized seeds to be sterile.
The reason you're having problems locating the seeds on your existing geraniums is because they launch their seeds as soon as they mature, which makes them notoriously challenging to collect. The best way to capture them before they go shooting off into nature is to tie a cloth bag around the flowers as soon as the blooms begin to fade and to leave it there until the flower stems eventually turn brown.
(Since geraniums are one of those plants that need to be deadheaded regularly to encourage them to continue flowering, you may want to keep a plant solely for the purpose of collecting seeds.)
Another thing you need to know is geranium seeds often germinate better when they have been cold-treated, so as soon as you gather them from your cloth bag, stick them in a container in the refrigerator. Twenty-four hours prior to sowing, begin soaking the seeds to soften their outer coats in preparation for planting.
Since geranium seedlings are slow-growing, the seeds need to be started in late January or early February to ensure that the plants will flower by early summer. The seedlings are also prone to damp-off, a nasty fungal infection that can wipe out an entire flat in no time, so make sure that any containers used for planting have been bleached, equipped with adequate drainage, and filled with a good quality soilless mix.
Now here’s the fun part: geranium seeds require daytime temperatures of between 21 and 24 degrees Celsius and night time temperatures of between 15 to 18 degrees Celsius for a period of seven to ten days just to germinate. The resulting seedlings require twelve to sixteen hours of full-spectrum light per day or they will turn out spindly. These are difficult requirements to meet in the dead of winter, so grow lights and bottom heat will take you a long way towards success.
If after reading all of this you still want to collect your own geraniums seeds, go for it. I personally am an advocate for experimentation and perseverance, which means I'm rarely put off by tales of caution, especially when it come to gardening.
If you have any questions or comments, please send them to me at vanessa@gardenmuse.ca.
