The Shoestring Gardener
Home / Species & Cultivars / Growing Begonia From Seed

Growing Begonia From Seed

Growing Begonia from seed, just requires a little patience!

By Brad Thaompson

Growing begonias from seed can seem like something that only commercial growers and experts can do, but let me assure you that it’s possible for anyone to grow seed. The article below will show you the methods that I have used for years with very good results. They aren’t the only methods, by all means, but have been successful for me and will be for you also if you haven’t already developed good methods of your own. If you’re successful already; then continue with what you’re doing; don’t mess with a good thing, but if you are having problems, this article just may help you.

If you’ve gotten some begonia seed you need to know how to grow it, if you don’t already. It really isn’t complicated, but does require reasonably sterile conditions, some dexterity and a lot of patience. In return, you get to watch little miracles happen. If you follow the steps I outline below, you should have no trouble growing seed into mature plants. I’ll also try to outline problems that you may run into, and my solutions. I start planting seed in September or October when the weather is cool and stop planting in January so that all of the seedlings will hopefully be large enough to go outside in April or May, but seed can be started any time of the year..

1. What You Need:

a) Seed: First of all, you need some good seed but that really goes without saying.

b) Light: The most important thing you must have to be successful with seed is to have a fluorescent light setup to grow them under. Although you could conceivably start the seed on a window sill, you won’t be successful growing seed without a light setup unless, of course, you have your own greenhouse. Seedlings require a great deal of even bright light in order to form compact robust seedlings and you won’t get that on a window sill. You’ll get leggy one-sided seedlings that won’t transplant well and will probably not be strong enough to make it to maturity. Under a light setup they receive constant light from straight overhead so you won’t end up with those scraggly leaners like you would in a window.

As far as the light setup goes, you don’t need some fancy elaborate light stand, you can make your own with just a simple cheap shoplight, hung wherever you have the room. You don’t need expensive bulbs either. I use whatever is on sale, usually cool white bulbs which will work fine. Sure those gro-lights may be even better but not enough better to justify the expense, especially when you have to replace them every six or eight months.

c) Potting soil: For a mix to start seed in I use one part peat moss (or sunshine number 3), with a third to half as much #2 (small) perlite. You don’t have to be real particular because you could probably go with equal parts of each if you wanted with no trouble.

d) Fertilizer: When planting the seed, I use one quarter strength fertilizer. I use Miracle-Gro (TM), but you can use any fertilizer with roughly equal numbers. I also put in a few drops of Superthrive (TM) (vitamin B-l) just for a little extra help. I don’t know for sure if it makes any difference to the plants but I feel better. I’ve used it for so long that I really can’t remember what a difference it made when I first started using it, but it must have been good.

e) Containers: I plant my seed either in 1 1/2 inch pots or take condiment cups and put holes in the bottom to make my own pots – either works just as good as the other. Some people use shallow trays but they take up too much space under lights if you’re planting very many varieties at one time. After they’re planted, I put the pots in a small clear plastic shoe box with a clear lid on top. Any small, clear container with a clear lid will work as long as it doesn’t have air holes in it.

2. What to Do:

a) First you need to sterilize the container that you’re going to put the pots of seed into (the shoe box), and you can do this by filling with very hot water with a dollop of bleach in it. No, I don’t know how much a dollop is. I just put some in, probably an eighth of a cup or so, and let it sit with the water up to the rim for awhile, usually about an hour or so, and also do the lid likewise. After that, I rinse thoroughly with more hot water (don’t get the bleach on your hands, use gloves) and then I put the lid on the box to keep spores and stuff out until I use it.

b) Second, prepare the potting mix as above and pack it down gently in your little pots almost to the rim, allowing a quarter of an inch or so for watering. Next prepare the fertilizer water using boiling hot water and use it to soak all of your little pots of soil, I let them sit in the water for awhile. This has two benefits. One is the hot water will soak into the peat moss better so will thoroughly wet it and will also sterilize your soil mix at the same time. Make sure you use pots that won’t melt in boiling water. I leave them soaking in the water until after all of the pots are planted, taking each one out, planting it then putting it back to make sure the seed on the surface gets wet also. (No don’t submerge them in water, silly, I’m talking about a half inch or so of water in the tray.)

c) Third, plant the seed. To plant the seed, you need to first make a label with the name of what you are planting on it and the date. Put it into the pot before you plant it. (There is nothing worse than planting twelve packets of seed and when you’re done finding out you only filled eleven pots so you double planted one.)

Next, plant the seed the way you cleaned it (see hybridizing article on the Hybridizing Page), tilting the paper and rolling the seed off evenly onto the pot, (after the soil has cooled a little of course.) Make sure you do your planting away from the other pots you’re planting because the seed is so small you could end up with some of it in nearby pots if you aren’t careful.

Let maybe 50 or a hundred seeds roll off, if you don’t have good vision, you’ll just have to wing it and, hopefully, you’ll see that something is rolling off and just guess that you’ve planted enough. If you plant less seed, they may not come up well (I guess they like company because any time I have a pot of seed where only a couple come up they don’t seem to grow as fast as a fuller pot) and if you plant too many seeds, you’ll have trouble separating them.

After you’ve rolled them into the pot, you’re done. Don’t cover them (begonia seed needs light to germinate) or pack them down; just let them rest on the surface where they fell. Place the pot back in the tray of water to soak a little more (it may seem like we’re doing a lot of soaking but you want the soil to be all the way wet, because the seed won’t germinate if the surface dries out during the sprouting process. You don’t want to have to water them again before you do the first transplanting.) After you have planted all of your little pots (again, they seem to like company, so try to have a container that is shallow and that you’re planting enough little pots to reasonably fill it. That’s why a plastic shoe box works so well, it’s shallow and only fits 10 to 15 little pots at a time, which is a reasonable number to work with for each planting.)

After all of the little pots are filled and labeled, I take them out of the tray of water and put them on newspaper for a couple of minutes to drain; then, place them into the shoe box and under the lights. I put the lights 6 inches or less from the top of the box and try to run them for at least 14 hours a day. I have left them on 24 hours a day with good results but that was a waste of electricity.

The seedlings vary in sprouting time depending on the variety and the age of the seed but can come up as quickly as 4 days or as long as a month. I have heard it reported that some varieties take months to germinate but I guess I will never grow any of those because, if nothing comes up in a month or so, I remove the pot and count it as a loss.

3. Potential Problems:

a) If the surface of your mix appears to be drying out before the seed germinates, or even afterwards, you didn’t soak your pots well enough or you have too much bottom heat. You can rewet them by setting the pots in water to soak, leave them in until the surface is wet, and no, do not use boiling water this time.

b) If you see a slimy black or greenish substance on the surface of the soil, you have an algae problem and either the seed had spores in it or you didn’t sterilize well enough. You can save any seedlings that look like they are in danger of being smothered by transplanting them right away. It is a delicate procedure when they are that small especially if you lack dexterity. But they really don’t have any problem with the transfer as long as you got them out with some roots attached. Sometimes, moss spores grow and these will smother out the seedlings if you don’t transplant them right away because it grows faster than the seedlings.

c) If you have a problem with damping off, (the little seedlings start to grow but then seem to rot off or collapse) then you have one of several problems. The pots are too large for the seed and they’re staying too wet, you didn’t use enough perlite in your mix so it’s staying too wet, you used pots without drainage holes so the mix is staying too wet (are you getting the clue that the main problem is too wet) or you didn’t have sterile enough conditions so disease spores grew in your box. A proper mix of peat moss and perlite will stay just the perfect wetness for your seeds to start and grow in.

To try and solve this problem, make sure your little pots have holes in the bottom and then spray them with a fungicide. This may not help the seedlings but you will lose them for sure otherwise. Then, leave the lid of the box cracked open a half inch or so to let the pots dry out a little. Another possible cause is that the area where you have your light setup is too cold for growing seed; try a warmer location. Try to keep your conditions more sterile for the next batch you plant. I’ve really never had this problem occur in all the years I have been planting seed; so, if you have followed all the steps you shouldn’t have a problem.

d) If your seedlings appear to be tall and leggy, you don’t have your lights close enough or are not leaving them on for enough hours (or not using flourescent lights.)

Now you should be ready to start growing some begonia seed. Remember, there is seed available from the Auckland Begonia Circle Seed Fund: A full list of available seed can be obtained by sending a stamped addressed envelope to Val Cowie (the seed fund convener) c/- 2/147 Norman Lessor Drive, St Johns, Auckland.

Credits / references:
Brad Thompson | Brad’s Begonia World

The Shoestring Gardener Hundreds of Eco-Friendly Tips