Seed – When it comes to seed, there are many sources.

  • Commercial seed companies carry the more common garden varieties of Begonias, usually B. semperflorens or Dragonwing types.
  • American Begonia Society members have access to rarer and more exotic types of begonias, through the seed fund. Here’s where you’ll find cane-like, rhizomatous and rex cultorum seeds.
  • Online sources can provide many different species of Begonia, but be careful. You’ll want a reputable dealer and to avoid sources where the seed is harvested illegally from endangered plants.
  • Many times you can collect dried Begonia blossoms and harvest seed right from the dried blooms yourself.

A couple of things to remember:

  1. Store your seed in the refrigerator, in envelopes with the contents written on the outside. The refrigerator stays cool and keeps the humidity low, which is exactly what seeds need to be stored long-term. Avoid hot dry locations, as the heat can kill the seeds. Definitely do not leave seed out in full sunlight.
  2. Labels are critical. Storage containers, pots of germinating seed, individual plants as they grow always need a label to help you remember what they are. Even the professional hybridizers have learned their lessons and label every step of the way, because you may think you’ll remember what is in that pot or envelope, but eventually we all forget.

Light – How bright, how long, and what kind?

  • How bright?

Outdoors/Greenhouse – if you live where you have outdoor space or a greenhouse, you can grow your seed in any place with filtered sun, not direct, cooking hot sun, but placed in bright shade. Make sure containers are covered, to avoid rain damage and sheltered from windy conditions.

Indoors – Either fluorescent lights or LED lights work well for Begonia seed.  Place the lights between 12-18” over the pots you will be growing the seeds in. You could conceivably start the seed on a windowsill.

  • How long?

For seedlings, you always want a day length that is longer than 12 hours. 14 hours is even better, as the “longer” days encourage more growth and energy in your seedlings. Day length of less than 12 hours act as a signal to tell plants to stop growing, and get ready for winter.

Timers and settings – there are many simple timers you can plug electric lights into. If you are growing in a greenhouse, you can either have your lights turn on earlier than sunrise, before sunset and extending into the night, or you can have them turn on in the middle of the night (10 pm – 2 am) (but you may need to check and make sure you aren’t causing problems for your neighbors).

  • What kind of lights?

With sunlight, you just want to make sure it is bright, not hot direct sun, but as bright as possible without building up heat.

With electric lights, either fluorescent, coated or Gro light fluorescent, or LED will work. LED fixtures tend to produce less heat, so if you are worried about heat build up, that might be a better option.

Potting Mix

Potting soil is one of those questions where every person will have a different answer as to what works best, so in truth you’ll need to experiment a little bit to find what works for you. The key things you want are a fine textured soil mix, that holds moisture evenly for a long time, and good drainage so that excess water is not held around the seeds.

That being said, there are many different kinds of soil/media that are used:

  • Potting soils, especially those labelled for germinating seed are a great place to start. These potting mixes are finely milled, and a mixture of peat moss and perlite, with some fine bits of bark mulch.
  • Other growers swear by using long fibered sphagnum moss, the raw moss which is very different from peat moss.
  • Some add charcoal, others use calcined clay particles, but you can always customize things later. Start simply and learn what works for you.

Fertilizer

Begonias do not need a lot of fertilizer, especially when they are very small. Try watering seedlings with  ¼ strength fertilizer. You can use premade soluble fertilizers like Miracle-Gro™ or Peter’s™ as they are the easiest to dissolve and apply initially.

Avoid very strong fertilizer concentrations as they are essentially very salty and can burn the tender little seedlings. Fish Emulsion fertilizers are also a bad idea in the early seedlings stages, as they can have a very high salt level.

Containers

Here again, there are many different options, and you can have lots of success with all of them. Remember the key is to be able to seal the container initially to give the little seedlings very high humidity in which to begin growing.

  • Some people use 2” pots and place them in sealed tupperware containers until seedlings have reached transplantable size.
  • Others use clear plastic clamshells from the food industry as each one acts as a small greenhouse.
  • Plastic cups with holes poked in the bottom, old clear glass milk bottles on their side, condiment containers, the alternatives are endless. Just pick something that is simple and makes sense to you to get started.