How to grow Tuberous Begonia

Tuberous Begonias grow best in cooler shady areas. In Southern California that is our coastal areas in about 15 miles. . The further inland you go the more difficult it will be. We have so many micro climate areas and there is such a difference in gardens it's not a hard and fast rule.

The garden that has lots of fuchsias, impatiens, ferns and other plants growing will have a higher humidity and the begonias will grow more easily.
Yes, you can grow tuberous begonias where it is hotter and drier but it will be much more difficult.

Shade
You want to give your begonias some shade. Early morning sun or direct sun in late afternoon is OK. The sun that would give make you feel too warm if you sat in it for an hour or so is too bright and will burn the leaves. There are other newer different tuberous begonias that can take more sun and we'll talk about them at the end.

Handy Hint....Shade MapOne of the most useful things you can do in your garden is begin a shade/sun map. Most of us don't really know when any particular spot is sunny or shady. This is what you do. Make an outline sketch of areas of your garden. You'll need copies for all 4 seasons.
Go out into your garden at 9 am., noon time and 3 PM.
I like using colored pencils but different pencil shadings can do the same thing. At 9 a.m. shade in the areas that have full shade or full sun....or anything in between. Do the same thing at noon and at 3 P.M.. Using different colored pencils makes it easy.
You will then have an accurate idea of which areas are full sun or just partial. Do the same thing in each of the four seasons and keep those records where you can find them.

Soil

All begonias like good light well drained soil. Actually almost all plants would like this kind of soil. Unfortunately that is easier said than done.
How do you know what if your soil is "good light well drained' soil?
Really good soil is soft enough that you can easily push your spade or shovel down into the flower bed with about 2 to 3 hard pushes. If your spade bounces off the surface, you need to add lots of amendments before you plant. Humus, humus, humus! If you have real clay why not give up and plant your begonias in pots?

Of course, you can plant your begonias in flower beds, in pots or in hanging baskets. A very flexible plant they will be happy in any of the above.

Watering
Contrary to what most people believe they do not want to be over-watered. The heavier the soil the less often you will need to water. At Weidners the baskets and potted begonias are in our greenhouse soil mix. This is a very light soil mix and the begonias in this will need water more often than the ones you dig that have a regular outdoor soil.
Water them well, then let the soil dry out a little bit. Feel down in the soil a little to check for dryness before you water again.

Air circulation
Tuberous begonias like to have space between them so that the air can circulate. Planting too deep or planting with too many other plants close up to the stem can cause stem rot. This is where the stems close to the base just turn to mush and rot off. Having good air flow helps deter this. It is a fungal disease so spraying with any good mildew spray

Fertilizer

Yes, of course they want to be fed. How would you feel if you only got an occasional meal? Begonias are not terribly fussy. Any good liquid fertilizer is good.

In the Fall
Sometime in the fall your begonia will begin to decline. Blooming will stop or slow way down, the leaves begin to fall off and eventually the entire stem will fall off. You will be left with the storage tuber under the ground...sleeping the winter away. Think of a little hotel room sign over it saying, "Sleeping, Do not Disturb". If you have them, [we hope you bought more than one] in pots or baskets you can simply turn the pots over on their sides in a convenient corner and let them sleep. Baskets the same way. Many people are just too busy so the empty basket just hangs their and gets a little rain. Don't leave the water tube in if you water that way. In the ground you can leave them in and take your chances that the soil will not be so wet as to rot them or you can dig them up. If you dig them up, let the tuber dry off in a sunny dry spot. Place it in a safe box or bag with just a little slightly damp soil, peat moss or something. You want your tuber to be dry but not to so dry as to desiccate the tuber. Be sure to mark all pots, boxes, bags so that no one throws them out as trash. Let them sleep away until spring.

In the Spring
Sometime in the spring around March your tuber will begin to wake up. What do you do then?
Tubers left in baskets or pots. Give them one good drink of water and place in the warmest spot you have. Remember it is warmth and daylight that will wake your tuber up. It does no good and can rot your tuber for you to water a a lot There are no roots yet, there are no leaves yet. Hello...there is nothing there to use extra water! Too much water can rot your tuber and then you have lost it.
For tubers that are stored you can choose between two methods.
Method one is to simply put the tubers bare on a window sill or in a flat and wait to see that little pink bud appear. Then you can pot your tuber in some good soil and let it begin its spring growth cycle.
Method number two is to place your tubers in some good light soil mix with just an inch or less of soil on them. Water them in once and wait to see the growth begin. Either way there is a huge difference in when each tuber decides to wake up. Some wake early, some wake late and a few never wake up at all. Just like people.

Once you begin to see some growth, give your plants some bright shade and begin to carefully water. Don't kill it with too much water. As the first real leaves appear you can feed the first time with some half strength liquid fertilizer. We hope you are using Weidners Good Stuff but the truth is that any good well balanced liquid feed will do. After you have three to four leaves going well then you can begin to feed twice a month.
Basket varieties: You did remember to mark them didn't you? Your basket begonias will have a better form if you pinch out the growing tip to force the branches out sideways.
Now your begonias are off and growing you can bask in your success. Forget about the ones that didn't wake up. Gardening is for pleasure and life is too short to worry about failures. Come in to Weidners for some new spring plants and brag a little. We love to hear about your successes.

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