Discovering Streptocarpus

Originally presented at the 1998 AVSA Convention Show in Sacramento, California by Rob.

Why we love “streps” (and why you can too):

1.  They are tough.  Our experience has been that people who have had little luck with African violets can successfully grow streps.  They are a great flowering houseplant for people without “green thumbs”–which is true for many of the customers who come to our shop.

2.  They do equally well under natural and artificial light.  We grow under both, and they don’t seem to care.  We place them in the worst areas of the greenhouse, where we wouldn’t think of putting violets.  They do well in almost any window of the house, making them great for windowsill gardeners.

3.  Ease of grooming.  Since they grow multicrowned, there’s no nee to remove suckers.  Have a discolored leaf, or the plant’s too big?  Just trim it to any shape or size with scissors.

4.  Flowering potential.  Unlike violets that usually only produce one bloom stalk per leaf axil, streps will produce 6-10 bloom stalks in succession from each leaf.  A mature plant with lots of healthy leaves can produce lots of bloom.

5.  Ease of propagation.  A 2″ length of leaf, rooted in a 2 1/4″ pot, can produce 20-60 plantlets, far more than a single violet leaf.

6.  Fewer pest problems.  They are susceptible to the same pests as are violets–mites, thrips, and the like.  Mealy bug is the most likely problem but, from our experience, they are less likely to attract mite and thrip.

7.  They are spectacular.  There are few things more spectacular than a mature plant in full bloom (and they mature quickly).  Most visitors to our shop come with the intention of buying violets.  Many leave with a strep–and at least as many of our return customers are strep buyers.

How to grow Streptocarpus (at least how we do it):

To propagate, cut a length of leaf, then remove the center vein (or rib).  Place the two remaining halves, or sides of the leaf, center (or vein) side down into the rooting mix.  It will look just like “two slices of bread in a toaster”.  Younger, more heavily veined leaves will produce more plantlets.  Unlike violet plantlets, which produce pairs of leaves, each leaf that appears from a rooted strep cutting is a plant–you needn’t wait for pairs of leaves to appear.  Plant each of these into its own 2″ pot.

The plantlet will produce its first bloom in 1-3 months, depending upon variety and conditions.  At this point in time, we pot the plant into a 3″ pot, where it should continue to grow and bloom.  Unless it is a small, or compact, growing variety, most streps will then need repotting into a 5″ pot in another 6-10 weeks.  Shallow (azalea) pots are best.  Except for the largest growing varieties, or those grown large or for exhibition, this is the largest pot necessary.  About every 5-6 months, repot the plant, dividing it if needed, removing some of the old soil and rootball, and adding fresh soil.

Some Streptocarpus problems:

Generally speaking, streps are harder to kill than are violets, being more tolerant of neglect.  This is especially true of the better modern hybrids.  There are, however, some potential problems that you may encounter.

1.  Species and many older hybrids.  It is true that these can be intolerant of warm temperatures.  A prolonged period of temperatures much above 80f degrees can be the beginning of the end for some of the species.

2.  Unifoliate and/or “annual” species.  Some of the species are “unifoliate”, meaning that they produce only one mature leaf.  Though not necessarily difficult, these are not recommended for novices–i.e. if the leaf dies, the plant dies.  Many other species are “annuals” in that they will bloom, set seed, and then expire.  These are best kept growing by continually sowing seed and/or rooting leaves.

3.  Overwatering and/or too dense a soil mix.  This is really the only way one can kill most modern streptocarpus hybrids, and is the most common problem of novice growers.  Streps almost always will recover from lack of water, even when almost totally limp, but can be killed by continual overwatering.  For this same reason, a lighter soil mix is always preferred over a heavy one.

4.  “Browned or yellowed” leaf tips or margins.  This can be caused by many kinds of stress, but the most common causes are infrequent or improper repotting and/or lack of grooming.  Sometimes that leaf is yellow simply because it’s old and should be removed!  These symptoms may also appear if the strep is very rootbound.

5.  Crowded and/or deformed center growth.  Streps are very fast, vigorous growers, and need to be divided and repotted into fresh soil at least every 6 months.  When very rootbound, especially in very old soil, center growth may show these symptoms.  In extreme cases, it can be mistaken for a mite infestation.

6.  Lack of bloom.  This is rarely a problem for us–we have had some plants that have been in bloom (or about to) every day of the year for four and five years running.  If it does stop blooming, and culture (i.e. feeding, light, etc.) is good, it may be because there is too much “old” growth.  Each leaf will produce 6-10 bloom stalks but, after that, will stop producing more buds.  Unless there are new, healthy, leaves being produced, blooming will eventually cease.  Dividing and repotting, giving the plant a fresh start, usually solves this problem.

Some suggestions:

Here are a few, simple, “rules of thumb” in growing streps that should increase your chances for success.

1.  Use very light soil mixes.  Especially true if you wick-water or otherwise plan to keep your plants constantly moist.  If wicking, we would suggest using a mix of at least 50% perlite.  It’s also a good idea to let the reservoir go dry occasionally before refilling (this goes for violets, too).  Keeping too-dense a soil, too wet, is the most common problem growers have.  Keep those roots happy!

2.  Use a balanced fertilizer.  “Bloom boosting”, or high phosphorus, fertilizers are not necessary for good blooming.  If you have healthy roots and leaves, blooms will come.  Streps are very vigorous growers and need to be fed regularly and adequately.

3.  Regular grooming and pruning.  Don’t be afraid to remove old leaves, especially if they’ve already produced a number of bloom stalks.  Also remove leaves that seem to be “competing” for the same space, or getting in each other’s way.  Remember, also, that leaves can be trimmed with virtually no effect on blooming–we’ve had pots of “stubble” in heavy bloom!

4.  Regular repotting.  If a strep has healthy roots, it’s happy.  If it doesn’t, it won’t be.  Proper pot size, and fresh soil, are needed for new, healthy, root development.  Neglect here is the second most common problem.  Be sure to water more sparingly until new roots have begun to grow into the added soil.

5.  Don’t overcrowd.  This goes for violets (and all plants) too.  Don’t create a “jungle-like” environment.  Threat them like weeds, and they’ll grow and look like weeds.

Future possibilities (what we look for in seedlings):

What we, as hybridizers, are looking for are qualities that don’t already exist, or need perfecting, and those that make the plant easy to grow.  As commercial sellers, we also want a plant that will be marketable (what people will buy), propagates and grows quickly, transports well (for shipping), and is unique to us (as opposed to other sellers).  Here are some of our current goals in our breeding program:

1. Plants that are tolerant of neglect and adverse growing conditions.

2.  Small, compact growers preferred.  So that they can fit on a windowsill, and more can be fit onto a light garden shelf.  Glossy leaves, sometimes with dark and/or red-backing, growing in a flat (not upright) manner, preferably in a rounded (even rosette) form.

3.  Long lasting blooms that are stick-tite and will hold up to mailing, transportation to shows, and handling.  Double, or triple, blossoms are preferred for this reason.  So that plants can easily fit onto light stand shelves, short, stiff, bloom stalks, with five or more blooms per stem, are desirable.

4.  Unusual colors, like fantasies, multicolors, and edges.  The possible colors, and combination of colors, are nearly limitless.  Unusual shapes and textures, such as frilled or velvety blooms.

5.  Even better, how about variegated leaves and fragrant blooms?  Such hybrids are just now making their way into the hobby.  They presently leave much to be desired with respect to growing ease and performance, but the possibilities for something really spectacular is there.

Many of these have already been achieved, by us and other hybridizers, to a degree.  The future is exciting!