Growing Begonia Seed
by Brad Thompson
If youíve gotten some begonia seed you need to know how to grow it, if you donít already. It really isnít 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. Iíll 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 wonít 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 wonít get that on a window sill. Youíll get leggy one-sided seedlings that wonít 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 wonít end up with those scraggly leaners like you would in a window. As far as the light setup goes, you donít need some fancy elaborate light stand, you can make your own with just a simple cheap shoplight, hung wherever you have the room. You donít 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 donít 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 donít know for sure if it makes any difference to the plants but I feel better. Iíve used it for so long that I really canít 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 youíre planting very many varieties at one time. After theyíre 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 doesnít have air holes in it.
2. What to Do:
a) First you need to sterilize the container that youíre 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 donít 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 (donít 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 wonít 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 donít submerge them in water, silly, Iím 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 youíre 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 youíre planting because the seed is so small you could end up with some of it in nearby pots if you arenít careful. Let maybe 50 or a hundred seeds roll off, if you donít have good vision, youíll just have to wing it and, hopefully, youíll see that something is rolling off and just guess that youíve 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 donít seem to grow as fast as a fuller pot) and if you plant too many seeds, youíll have trouble separating them. After youíve rolled them into the pot, youíre done. Donít 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 weíre doing a lot of soaking but you want the soil to be all the way wet, because the seed wonít germinate if the surface dries out during the sprouting process. You donít 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 youíre planting enough little pots to reasonably fill it. Thatís why a plastic shoe box works so well, itís 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 didnít 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 didnít 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 donít 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 donít 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 theyíre staying too wet, you didnít use enough perlite in your mix so itís 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 didnít 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. Iíve really never had this problem occur in all the years I have been planting seed; so, if you have followed all the steps you shouldnít have a problem.
d) If your seedlings appear to be tall and leggy, you donít 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 Seed Fund that you can try if you are an ABS member.
Part Two: Growing Begonia Seed
In the first part we talked about getting seed and how to plant it. This time weíll talk about where you go from there and how you go about transplanting those little things. It isnít that difficult but this is where most people fail at growing seed if they got them to come up in the first place: that horrifying first transplanting. Most failures are due to unsterile or too wet conditions which are easily fatal to begonias at this size and stage of development.
1. When to transplant: Although seedlings can be transplanted just as soon as they come up, it is best to wait for them to get larger before transplanting unless you are experienced. When the seedlings first emerge, they have only a pair of equal sized leaves. These are the seedling leaves and nourish the plantlet until it has formed enough roots to support itself. The seedlings at this point have only one little root trying to work its way into the soil. Within a week or so after the plantlet comes up it starts to form its first true leaf. (If you have ever looked at a begonia plant , you will notice that it puts outs one alternating leaf at a time unlike some other plants which put them out in pairs.) When this first leaf is out and is about a half an inch around is the proper size for transplanting. The reason for this is that it has now reached the stage where it has formed some roots but not so many roots that you wonít be able to separate the little plantlets. I separate the little plantlets by grabbing the one true leaf and gently using it to pull the plantlet out of the mix. Of course, you will ruin some but you will have plenty regardless. If your mix is too hard and the seedlings donít come out easily you can use a knife tip to break up the soil a little first but itís better not to if you donít have to. As long as your seedling has a root or two after you pull it out it will be fine. I usually only transplant about 25, or so, out of the pot at a time and save the remaining ones in case anything goes wrong with the first batch. The ones left in the pot will not grow much because they quickly run out of food but in the humidity of the sweater box they will sit there in suspended animation for a long time - sometimes up to a year. If they dry out soak them to rewater, donít overhead water.
2. What to pot them in: Transplant the seedlings into the same conditions you are removing them from. Use the same soilless mix such as peat and perlite, or Sunshine #3 and perlite, and keep them in a sweater box or clear covered container, at least until the next transplanting. You can either put the mix in shallow trays and transplant the seedlings in little rows or you can use regular seedling trays cut to fit your container which have separate little compartments for each seedling. The ones I use have individual 1/2 inch squares for each seedling and seem to work very well. I have used sandwich boxes, cut in half (bottom and top, not cut the other way), and put four or five holes in the bottom for drainage. These worked well too and are certainly easier to clean than the commercial seedling trays I use. I put a shallow layer of my mix in each tray and sterilize it by watering with the boiling hot water with fertilizer (light fertilizer, 1/4 strength) and let the trays of mix soak for a while to absorb the proper amount of water and to cool off. After they have cooled a little, I set them on newspaper to drain, usually tipped slightly on edge so they drain easier. I then take a pencil or pen and use the point to make little holes 1/4 inch deep, or so, at regular spacing, about 1/2 inch apart for the seedlings to go into. I also sterilize a sweater box, for them to go into after theyíre planted, with a bleach and hot water solution (as described in the earlier installments of this article) and after the sweater box is dry I put several layers of newspaper in the bottom. This will absorb any extra moisture from condensation later when you have the trays in it so they wonít be sitting in water.
3. Transplanting: Once you have everything prepared, get your pot of seedlings and immediately copy the label and put it in the tray where you are going to transplant so you wonít forget to do it later. No, you wonít remember what they were no matter how well intentioned you are, as I can swear to, (as can Mary Sakamoto when sheís looked in a sweater box and said, ďOh what are these? There isnít a label, and I suddenly remember that I donít remember.Ē Avoid the confusion and label first. Pull up a seedling, as described above, and set it into the hole you made with the pencil. If it doesnít fit then make your holes a little bigger. Repeat this process until youíve transplanted as many as you want. Then go back with your pencil, or whatever your favorite utensil is, and smooth around any that need it. They donít need much tamping around; if you made contact with the soil they will root and grow. If you soaked the mix properly in the first place, they shouldnít need any further watering until they are ready for the next transplanting. If any start to die or rot, you have the mix too wet so open the lid a crack to let it dry out some. If that doesnít work and they are still dying off, then, as a last resort spray them with a fungicide to try and kill the fungus problem the too wet conditions created. Donít be discouraged if you have some failures. Count those as learning experiences and try again. If you really think you need extra help, come to my house and visit and Iíll give you plenty of first-hand experience to take home with you.
4. Where to go from there: About a month or month and a half from that first transplanting they should have grown to fill the surface of the box. Its time to move them up again. At this stage they are running out of food and are becoming too crowded. Theyíll either just sit there and not grow any more or theyíll get leggy and be hard to make into nice plants and transplant. They should be ready to transplant into small 1 to 1 1/2 inch size pots. You donít have to be quite as concerned at this stage about perfectly sterile conditions as in the earlier stages but your sweater box should be sterilized. If you do encounter problems, you will have to sterilize the mix too for later batches. Peat and perlite or Sunshine #3 are already pretty sterile on their own since they contain no soil. If you wish to sterilize the mix, fill your little pots, place them in a tray and water with the boiling water/fertilizer mix, as in the above instructions, before you plant. You can use a knife tip to make an opening in the mix to receive the little plant. I use my mix dry, transplant the little plant and put the pots in a shallow tray filled with the cold or room temperature fertilizer water (not boiling water of course) to soak. Make sure to label each pot as you go so you wonít miss any, or if only one type of seedlings are going in one sweater box you can just put in one label for the box and label them before you take them out. I usually move the plantlets out of the sweater box at this size or after they have reached the next size pot and put them under light shelves that are totally covered in plastic to keep the humidity in. I place the small pots on a shallow tray filled with a layer of perlite to soak up any water from watering the plants and also to raise the humidity. Watering the perlite occasionally to keep it moist is necessary because the runoff from watering the little pots is not enough. After they have grown to fill these pots, you can treat them like regular plants. Lift the plastic cover gradually to harden them off and then transplant in your regular mix. If it is warm enough, you can move them outside in full shade for another couple of weeks and then start moving them into your regular growing areas.
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