Growing Streptocarpus: Germinating Seeds

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Robert Pavlis

Streptocarpus seeds are some of the tiniest you will ever sow but they are also very easy to germinate if you follow these simple instructions.

top view of a pot showing very tiny green seedlings
Streptocarpus seedlings – 3 weeks after seeding – 4″ pot
  • Surface sow in pots.
  • Streptocarpus seed needs light to germinate.

Sowing Seeds

The best way to germinate streptocarpus seeds is to do them in a community pot. Once they germinate and grow to a reasonable size they can be pricked out and potted up individually.

Take a 4 inch pot and fill it with your favorite potting media. Pack the media down tight. Since the seeds are very small you want to prevent them from settling too deep in the pot. Compacting the media helps keep them near the surface.

Set the pot in a tray of water and let it sit until the top of the media is quite wet.

Now sprinkle the seeds onto the media. Because of their small size, it can be difficult to get even spacing. A good technique for spreading the seeds is shown in this video:

Video: Growing Streptocarpus From Seed.

Suggested Trick: Plant only a few seeds at one time. Thirty seeds in a 4″ pot is lots. Save the rest of the seed for a future seeding.

Food Science for Gardeners, by Robert Pavlis

Place the pot in a baggy and seal it. I do this by simply folding the top over. A domed container also works. Now place the baggy in a well-lit area at room temperature and wait. Germination usually begins in 7 to 12 days.

two pots insdie a plastic baggy

Once enough seedlings have germinated, partially open the baggy and allow some air into it. This will reduce the humidity in the bag. A few days later, roll the bag down a bit more. Slowly expose the seedlings to less humidity so that a week later they are exposed to normal room humidity.

The majority of seedlings germinate around the 10 day mark, but some seeds will germinate over the following couple of weeks and a few may take more than a month to germinate. I have found newly germinated seed under flowering seedlings.

Light Requirements for Germination

Information about germination is sparse from both scientific circles and hobbyists.

Research done on Streptocarpus rexii found that seeds did not germinate in the dark and required light for at least 5 days to achieve significant germination levels.

I found no information about the light requirements for hybrid streptocarpus seeds, so I conducted the experiments described below.

Based on this information it is best to germinate seed in light conditions.

Where Do You Get Seeds and Plants?

I sell seeds, leaves, and plants on this website.

Ordering seeds

Ordering leaves

Ordering plants

flower spike with several flowers, white with dark pink strips.
Streptocarpus RP Lacey Bloomers

Potting Up Seedlings

Streptocarpus germinate easily but the new seedlings are very tiny and they don’t grow very much for a couple of months. Then they seem to take off, relatively speaking, and if grown properly flower in 4 to 6 months from seeding. An important step is to prevent them from getting too crowded.

Consider moving them after the first month. They are still small but can be moved to larger quarters. I prefer to move them to community pots where each seedling is about 1/2″ away from its neighbors. Once the leaves touch it is time to move them again, either into another community pot or into their own pot.

Video: Potting Up Seedlings – Streptocarpus – Pricking Out and Transplanting

Once the seedlings start to grow it is important to give them fertilizer and good light as described in Growing Streptocarpus: Light Conditions.

Experiment #1: Light Requirements for Germination

Seeds collected from Streptocarpus RP Lacey Bloomers (see above picture) were used for these tests. Two different germination methods were used: the baggy method and the pot method.

  • Baggy Method. This is my standard seed germination method which uses a paper towel and baggy. The advantage of this method is that you can visually see the seed during the complete experiment. This allows you to measure the time of germination and count the % germination.
  • Pot Method. This is the method that is described above in Sowing Seeds. It is my standard method for very tiny seed especially if they do not require a stratification treatment.
Streptocarpus seeds germinating in baggy method

Duplicates of each method were prepared on the same day. One set was kept in my plant room and received a low level of light for about 12 hours a day. The second set was placed in a cupboard in a dark room next to the plant room. The temperature of both rooms was very similar. Except for a few seconds every few days, the dark samples were in complete darkness all day.

Experiment DurationGermination
Seeds in Light
Germination
Seeds in Dark
Day 0 – seedingnonenone
Day 8several in pot, one in baggynone
Day 11lots of sprouts in pot and baggynone
Day 27 – move to lightlotsnone
Day 38lotslots

On Day 27, both the pot and baggy that were in the dark were moved to the same light condition as the seeds with the light treatment to see if they would germinate.

Microbe Science for Gardeners Book, by Robert Pavlis

The experiment clearly shows that hybrid streptocarpus seed requires light to germinate. This agrees with research done on S. rexii.

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Robert Pavlis

I have been gardening my whole life and have a science background. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

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