One of the greatest wonders to be seen in this wonderful business of growing plants indoors or out is the sprouting of a brown, dead-looking seed. And even more miraculous is the sprouting of seeds so tiny they cannot be discerned from a particle of dust. Such is the amazement you will experience when you plant your first semperflorens (wax) begonia seed.
Of all the plants which produce dust-like seed, wax begonias surely head the list as being easiest to germinate, and if you keep them growing until their first true leaf is an eighth of an inch across, you will probably be successful in flowering your baby begonias.
Begonia seeds need warmth and constant moisture to germinate. Plastic dishes (from Chinese take-out) are ideal for planting containers. Start the procedure by punching a few drainage holes in the bottom of the container with a heated ice pick. Over these drainage holes, place some coarse sphagnum moss, or pebbles, to a depth of about a half inch. On top of this, a mixture of peat mos and sand should be placed to a depth of one inch. Over this, use a third of an inch of fine vermiculite or screened sphagnum moss.
Make this top layer smooth and set the container in a pan of water until water soaks through the drainage holes up to the top of the mixture. Allow this mixture to drain, and then dust the begonia seed over the top of the mixture. Do not cover them. Simply place the plastic cover of the dish over them, and set the container in a warm place (70-80 degrees) to expedite germination.
Light and Seed Germination
They do not need light for germination. Watch the top of the dish for drops of moisture condensation. When these appear, remove the top and wipe dry, and then replace.
In about ten days when the tiny green plants begin to appear, move the dish to where the plants will receive good light, and perhaps some early morning sun, provided that hot sun is not allowed to shine on them directly for more than a few minutes. As germination seems to be completed, leave the top off for a few minutes each day, gradually increasing the time until the lid does not have water soaks through the drainage holes up to the top of the mixture.
Never let the seedlings dry out. They will need plenty of sunlight to keep them from becoming leggy or spindly. A daytime temperature of 72-75 degrees with a ten degree drop at night is ideal.
If you planted the seed thinly enough, it is likely that you can wait until the baby plants have several true leaves before you transplant them. If you planted thickly, as soon as they have one or two true leaves, begin to transplant them.
In the greenhouse, put the seedlings in flats of soil, if possible otherwise, into individual small pots. In the window garden, inexpensive small plastic flats are ideal. They are light, easy to handle, and they are attractive to have on a windowsill.
Ten or twelve plants may be grouped together in a six or eight inch community bulb pan or pot. This soil mixture for transplanting may be one of the good potting soils found down at the local garden center.
Begonias like a loose, but rich soil… especially one rich in organic matter. If you allowed two inches between the seedlings at transplanting time, it is likely that they may be left in these containers until May or early June when you may take them outdoors to use in your garden.
If they become crowded in these first containers, move them into individual pots, or take a few from each flat, pot them, and use them in your window garden, as greenhouse specimens, or give them to your friends.
Light applications of house plant fertilizer are worthwhile after the plants are five or six weeks old.
Wax begonias are ideal for use in the outdoor garden, and some sunlight gives their leaves a shiny bronze color which cannot be excelled. Blossoms come freely from well grown seedlings four months old, and a grouping of begonias will give flower and foliage color from June until the nights become chilly in September.
Cuttings may be taken of favorite plants, or you may give the plants a severe pruning both above and below the soil line and place them in flats of soil in which you can winter them in the greenhouse. For the window garden, take a few cuttings and pot two or three to each six inch pot preferably a bulb pan or “squatty” pot because begonia roots like to spread out instead of down.
Year after year, for outdoor bedding purposes, it is best to start from new seed each winter or very early spring. Seedsmen offer many named varieties of semperflorens begonias, which come in three categories: dwarf, six to eight inches, medium, nine to eleven inches; and tall, over twelve inches.
When planting in the border, they should be planted close together for a mass effect with up to six plants in each planting, preferably of the same variety for emphasis in color. These begonias combine beautifully with other shady border plants such as impatiens, caladiums, summer blooming oxalis, coleus and tuberous rooted begonias.
All types of begonias may be grown from seed, and the procedure for the most difficult to grow varieties is not much different than the method described here.