What to do with my outside bonsai during winter?

Like I said in my post about the orchids, you do not have to worry about winter care of bonsai if you live in the tropics, but if you don't maybe you find this information useful for you.

You must become familiar with the specific varieties of bonsai you have to determine if protection (or how much protection) is required. For example the tropical bonsai candidates, such as the desert rose (Adenium obesum), can be treated as houseplants, but the vast majority of bonsai are temperate plants (not tropical) and they definitely need to be left outdoors. The most familiar bonsai specimens are hardy trees — either evergreen or deciduous. These rarely should be treated as houseplants in the winter--and then only in areas where the winters are extremely severe — because they have the same growing requirements as their full-size counterparts, and they need the same seasonal growth cycles. So leave them outside. Heel them in by burying their pots in the ground in an area where they are protected from snow cover and covered with a protective layer of mulch. If the temperatures drop well below that which the plants are hardy to, move them into an unheated garage for two or three days or into the house for up to a week or two, provided they receive adequate light and temperatures are cool (60 to 65 degrees).

The concept of wintering over a bonsai is not too much different from wintering over what is already planted in your yard. Most temperate climate trees grown as bonsai are capable of handling the severe weather as long as a few simple conditions are met. 

It's better to allow them to go through a couple of light frosts at least - junipers can take anything down to 15-20 Fahr., and need to get cold to go dormant. 

Remember that winter winds combined with temperatures below the mid twenties Fahrenheit (or below -5 Celsius) will freeze dry almost any bonsai. 

But ting to keep temperate plants warm by placing them in the sun is a mistake. The added warmth from exposure to too much direct sun can cause a tree to wake up from dormancy too early. If this is followed by temperatures once again plunging down very low, the water in the sap can freeze within the cambium layer and kill the tree. So, please do not put an outdoor bonsai in a heated house for the winter.

Usually it is usually not necessary to take trees out of their pots. Good pots are capable of handling the temperature changes. One exception would be Trident Maple. This particular tree should be removed from its pot and the soil ball buried in the ground or a large box. If it is wintered in the pot the roots will turn to mush.

All other temperate plants can be kept in a sheltered area out of direct sun and wind. The pots should be mulched or buried to the top of the rim in the earth. Burlap barriers work well as a wind break. You can also make a wall using bales of straw.

If there is not much snow or the weather warms it is possible you will have to water your trees from time to time. Here is a good tip: once the soil freezes, don't water If the soil ball thaws and starts to dry you must water. The soil should not get saturated with water that freezing and expansion could break the pot. Be careful not to overwater in winter, especially deciduous trees as a tree with no winter foliage uses very little water.

(For more information, Please refer to my post from last year regarding Bonsai care during winter HERE)

How to take care of your ochids in winter

If you grow orchids outside (temperature around 32 F., 0 C.) basically your orchids unfortunately will be. Most orchids are tropical type plants. Some orchids can survive freezing temperatures somewhat (Cymbidiums being a good example). But freezing temperatures over a continued period of time can really damage them as well.

So, If you think your orchids will freeze try to protect them. Bring them inside in a hallway, or perhaps behind a window (they look great in a kitchen window). The structure will give them some protection. If you can not bring them inside, snuggle them up close to the side of a house. Houses can give the plants the extra couple of degrees to help them through the coldest time. Move them into a greenhouse if you have one. 

Most Southern areas do not need to take special precautions for winter care of orchids except when a frost alert is in place. (For example here in Miami, we are still in the 80's or low 70's).

Orchids need a certain amount of light and temperature to grow normally and the winter season can change that. A significant number of plants will have this as a normal period of dormancy or rest needed to get ready for the next budding period.

Some orchid plants like Cattleya, Epidendrum, Dendrobium and Oncidium may possibly need some artificial light. The high intensity orchids need about 12 to 14 hours of light during their growing season and less than that puts them at a disadvantage for generating buds and blooms.

It is only in the extreme northern US latitudes that we don't find at least 14 hours of daylight. The intensity of the light may be diminished because the sun is lower in the atmosphere during the winter. So if your plant needs more light you may need to move them from an area of where they used to get bright diffused light to a sunnier area of the home. The use of grow lights is not out of the question either especially for those plants requiring high light intensity like Oncidums and Cattleys. Lighting is an important aspect of winter care of orchid plants and if the plants do not get enough they will not bud.

The winter care of orchid plants usually means less watering because there is a needed period of rest. Instead of watering twice a week try watering once a week or instead of watering once a week we need to do it every 10 to 14 days. Now this changes if your home has low humidity, in this case you will need to water more often. The normal humidity that orchid plants love is between 40 - 80%. Most homes have about 40 -50 % humidity. If your home does not you may need to use humidity trays. These are metal or plastic trays that are filled with pebbles and then about 1/2 with water. 

Since most orchids need temperatures between 55 - 80 degrees F, the plants in the middle and northern US need to come indoors. There are certain things we need to bear in mind. Normal home temperatures are usually good for orchid plants but we need to consider that if we keep our home temperatures low due to the high heating bills we may need to add some warmth during the day to the plants. It is not good to keep them at a constant 60 -65 degrees, they do need times with temperatures higher.

Be careful of the setting as well, a window sill in the day time may be wonderful for the plants but at night it may get too cool. In order to protect the plants use a curtain as a barrier to the cold. On the other hand the window sill can also burn plants if it gets too hot. By the way this damage also occurs with lack of water and over heating of the orchid plant.

The most common signs of cold injury include injury to the plant leaf which can be seen as pitting marks, large sunken areas or the eventual discoloration which can lead to a brown leaf. The amount of damage varies considerably with the cold injury. If a plant is frozen you will notice this rather fast after thawing. The dead spots on the leaves as well as the flowers and buds is easily noticeable.

This period is usually one of resting the need for fertilizer diminishes as well. You should stretch out the fertilizing to be twice as long as you would during the summer. For example if your routine for fertilizing was once a week in the summer than the winter care of orchid plants says that it now should be once every two to three weeks.