How to Keep Beautiful Re-Blooming Orchids

by Dr. Chris Kline

Orchids have become quite popular, resulting in their increasing availability and selection. This popularity is well deserved because there truly is something special about their exotic color and elegance. Sadly for many, orchids are treated almost like cut flowers because their owners fail to understand the plant’s needs particularly with regard to long term health and repeat blooming. The good news is that with a little know how orchids are not particularly hard to grow, and by understanding and addressing their unique characteristics and needs, one will be rewarded with repeat seasonal blooms as beautiful, or more beautiful, than those that motivated the purchase in the first place.

Getting off to a Good Start

It is possible with proper knowledge of orchid varieties to select varieties that are best suited to the home in which they are to be placed. The most critical environmental factor is temperature. For simplicity, orchids are generally grouped into cool-growing varieties (preferring daytime temperatures of 60 to 75 degrees F), intermediate-growing varieties (preferring daytime temperatures of 65 to 80 degrees F) and warm-growing varieties (preferring daytime temperatures of 70 to 85 degrees F).

One of the many advantages of buying orchids sold by professional growers or reputable nurseries, as opposed to discount stores, home centers or even grocery stores, is that the plants are more likely to be clearly labeled and advice may be available on the preferred growing conditions of each type available. Fortunately, if the growing environment can be maintained above 60F and not exceed 82F (well within the range in most homes) almost any orchid can be grown successfully. Provided that the temperatures are kept within this range, a more critical factor in growing and re-blooming orchids is the variation between daytime and nighttime temperatures.

Orchids are also available from several online sources. The selection is great and they generally guarantee safe arrival. There is a quite a bit of useful growing information on some of the online vendor sites and they even make searching for varieties based on color, bloom season, light requirements and other criteria easy. The following online vendors offer a large selection of orchids:

Orchids.com http://www.orchids.com/

Orchid Web www.orchidweb.com

Waldor Orchids http://www.waldor.com/

There are two basic categories of orchids. The most common are called epiphytic orchids and grow in trees in the wild. If an orchid comes potted in a course, quick-draining medium, generally some form of bark, it is likely a type epiphytic orchid. The quick-draining material is designed to help replicate short but heavy rains that occur in the plants natural environment. Terrestrial orchids, on the other hand, grow in the ground in the wild and are generally potted in some form of potting soil similar to that used to pot most house plants.

It is a good practice to repot epiphytic orchids after purchasing. Often these plants have been growing in the same pot for some time and the growing medium may have begun to decompose. By repotting, one can insure that the orchid is in fresh medium with quick-draining characteristics and that the roots are well conditioned.

Purchase an appropriate medium for epiphytic orchids which will generally contain large pieces of bark and charcoal to accommodate good drainage. Orchid-potting medium is available at nurseries and most home centers and can be found online at the following sites:

Green Barn Orchid Supplies www.greenbarnorchid.com

Home Harvest Garden Supply www.homeharvest.com

Kellie’s Korner Orchid Supplies www.kkorchid.com

Lone Star Orchids http://www.lonestarorchids.com/

Orchidsupplies.com www.orchidsupplies.com

Orchid Web http://www.orchidweb.com/

Tindara Garden and Orchid Supplies http://www.tindaraorchids.com/

US Orchid Supplies http://www.usorchidsupplies.com/

When repotting, it may be necessary to go to a slightly larger pot, but it is not necessary to have a great deal of extra space above that needed to accommodate the roots comfortably.  Orchid pots come in a variety of styles and can be purchased from the suppliers listed above. Most orchid pots are designed with holes in the sides to allow rapid soil drainage. Sometimes these holes are an inch or so from the bottom to allow a small amount of water to remain in the bottom of the pot. Carefully lift the orchid out of its pot and shake gently if needed to release the growing medium from the roots. Examine the roots and use scissors to clip away any dead or damaged roots or root tips, leaving only white healthy roots. Place a small mound of fresh medium in the pot, set the orchid on top and carefully fill medium around the roots so that the orchid sits up straight in the pot.

Now that we are off to a good start, there are several other important factors that must be addressed in order to keep orchids happy, healthy and most importantly beautiful.

Daytime vs. nighttime temperatures

The name of the game in gardening is to try to match the growing conditions to the natural environment of the plants as much as possible. In orchids’ natural habitats, evening temperatures are at least 10 to 15 degrees (F) lower than the daytime temperatures. The most common reason orchids don’t bloom indoors is that the environment does not have enough of a change in temperature between day and night. This temperature difference helps to induce the orchids to start the budding process.

Several things can be done to help produce a better day/night temperature differential. It is very helpful, regardless of where orchids are being grown, to have an inexpensive min/max thermometer that can be placed near the plants to monitor the minimum and maximum daily temperatures. These can be purchased for less than $20 from a number of online retailers including the following:

Home Harvest Garden Supply www.homeharvest.com

The Greenhouse Catalog www.greenhousecatalog.com

If plants are being grown in a climate controlled growing room, then a programmable thermostat (available at most hardware stores) will allow settings to be different for day and night to accommodate cooler nights. If plants are not being grown in a climate controlled grow room there are still several things that can be done to create a better day/night temperature differential. In fall and spring, orchids can be placed next to a window that is cracked at night. It is best to use a small curtain and/or position the plants so they are not in a direct cold draft. Another option is placing the plants in an unheated room at night.

Many people have good results by placing orchids outside when the summer high temperatures drop to 80F. This technique takes advantage of the natural variations between day and night temperatures. The plants can be kept outside until the low temperatures threaten to drop below 60F. If these outdoor growing conditions can be sustained for four or more weeks, there is a good chance for many orchid varieties to be triggered to bloom. This process can also be used in the spring when low temperatures become consistently above 60F, and can continue until high temperatures threaten to break 80F.

Light Requirements for Blooming

Perhaps the second most common reason for orchids not blooming is insufficient light. There are some indications that can be seen by looking at the foliage. Lush dark green leaves may look healthy, but a lighter grassy shade of green is more likely to indicate proper light for blooming. It is best to take the guess work out of determining light requirements by buying an inexpensive light meter and finding out the light requirements of the orchids being grown. As with temperature preferences, reputable growers or nurseries can give some guidance as to the light requirements of various verities of orchids. The following list gives light requirements for some popular varieties.

Phalaenopsis            1000+ fc

Cattleva                   2000-3000

Vandas (strap leaf)   3000-4000

Oncidiums               2000-3500

Paphs(mottled leaf) 1000

Paphs(strap leaf)    2000-3000

Psychopsis             1200-1800
Bulbophyllum         1800-2500

A source for inexpensive light meters is Grow Light Source http://www.growlightsource.com/

Watering

As with light and temperature concerns, the proper watering of orchids should attempt to mimic natural growing conditions. Epiphytic species grow in trees in tropical rainforests. Conditions can best be simulated by submerging the orchid pot into a container of water for a few minutes to soak the growing medium and then allowing the pot to drain well. Do this once each week, with perhaps a small squirt of top watering at mid week.

The exception to regular watering is that some orchids, like some of the dendrobiums, require a very dry period, up to several weeks, during the winter, when very little water should be given to the plants. This dry period mimics their native habitat, in which their winters are dry. The dry period triggers flower buds to form. Then when watering or natural rainfall begins in the spring, the buds are ready to swell and produce flowers. Once plants have set buds, it is very important for them to have consistent water to allow the buds to swell and flower.

Fertilizing

Orchids do not have high nutritional needs, but particularly with Epiphytic species grown in inert media it is important to fertilize regularly because the plants are not receiving nutrients from the growing medium. Most of the time orchids do well with a balanced fertilizer. It is possible to use a high nitrogen fertilizer to increase lush foliage, but if this is continued for too long, or into the blooming season, the high nitrogen will cause the plants not to bloom. A high phosphorous fertilizer is needed to give orchids the energy needed to grow new blooms and flowers.

Regardless of the fertilizer that is used, it is very important to avoid over fertilizing orchids. Fertilizers that are specially formulated for orchids will have guidelines that should be followed, but if using regular house plant fertilizer, it should be used at no more than half strength. Fertilizing every other week should be sufficient during most of the year and fertilizing can be eliminated or drastically reduced during the winter when watering is also cut back.

Even if one is very careful not to over fertilize, it is a good practice to leach orchid plants once a month by thoroughly watering them with plain water several times and allowing them to drain. This helps flush out the fertilizer salts that will build up over time. These two companies offer orchid specific fertilizers:

Orchid Focus Premium Orchid Food http://www.orchidfocus.com/

Grow More Orchid Fertilizer http://www.growmore.com/

Humidity

Orchids may not be stopped from budding by insufficient humidity, but they will certainly not perform at their best, and there is a possibility that if the air is too dry when the buds are forming, they may dry up before they open. Optimally, if the humidity in the growing environment can be kept above 60 percent, most orchids should be happy. One of the best ways to increase humidity, and add a great relaxing feature to the growing area, is to add a small indoor fountain. Another option that is also popular with bonsai enthusiasts is to use some form of shallow drip pan to set the orchids pots above that will create a more humid micro climate through evaporation. By using a plant mister often, humidity can be increased around orchid’s leaves and flowers. The best time to mist, to avoid encouraging fungus, is in the morning which allows leaves time to dry before nightfall.

After the Bloom

Once an orchid is finished blooming one must decide whether to cut off the spike or not. As a general practice it is best to leave the spike intact, unless or until it turns brown. Some species can grow a new spike from a node of the previous one and some even flower again from the original spike. Unless specific advice to the contrary has been give for a particular species from a reputable grower, no harm can come from leaving spikes on after a plant is done blooming. After all, plants grown in nature do not have their flower stalks cut off and it does not stop them from re-blooming.

Dr. Christopher J. Kline is a master gardener and writer living in Paradise Valley Arizona. Chris is a member of the Garden Writers Association and a columnist for Garden and Greenhouse Magazine www.gardenandgreenhouse.net. You can contact him at CKline72@Cox.net