Question
QUESTION: I have phals growing inside the house all year round but put my dendrobiums and cattleyas outside from May through October (Virginia coastal area).  I have been using the same fertilizer for years but now that I've come to the end of this box, I'm asking if I need to get different fertilizers for different orchids and if growing them indoors or a mix of indoors for the winter and outdoors for the warmer months makes a difference.  And do the numbers for N, P, and K make a big difference as well.  Thank you.

ANSWER: Corinne, your growing approaches seem fine. Feeding phals weakly with each watering is fine because they are almost always in growth.  On the other hand, Cattleyas can only benefit from feeding when they are in their active growth cycle. Since they are exposed to more light, they could be fed with a slightly more concentrated plant food.  As a general rule, orchids can only make use of suppllemental feeding when they are in active growth, so suspend the feeding when they have finished their growth.  When these plants approach or begin their bloom period, you can make effective use of a bloom booster plant food.

Both cattleyas and dendrobiums have a rest period after completing growth.  It is important that this rest period be respected by not only suspending feeding but by cutting way back on watering. You may be able to suspend watering entirely during this time in favor of misting since the purpose is to prevent the pseudobulbs and canes from shriveling too much.  Keeping these plants wet during rest could cause rot and result in the loss of the plant.  

For actively growing plants, nitrogen (N) promotes growth so you want the N to be equal to or higher than the numbers for P and K.  Phosphorous (P) can boost flowering and improve flower color. Fertilizers with a  high P value are called "bloom boosters".

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QUESTION: Many thanks for your very informative answer. It is very much appreciated.  As a follow-up, I would like your opinion on when to consider the dendrobiums and cattleyas in their dormant stage.  Does this coincide with the onset of cooler weather here on the East Coast (around the end of October to early November)?  Normally they appear to be 'growing' such as sending out new canes or leads from late spring and throughout the warmer summer and early fall months.

Second question: I usually stage my orchids from the fresher air of the outdoors when night temps drop to 50 degrees or cooler.  I first move them to the protected garage before bringing the orchids into the warm but much drier air of the house (I do have a whole-house humidifier that I set at 40% for human comfort).  I use these few days to try to eliminate as much of the bugs and pests that have taken up residence in the pots.  How do you recommend I do this with least toxicity to the orchids?  I have soaked the pots in water but have not yet found any good method of eliminating ants and roly polly bugs.  They still come into the house but normally they stay in the pots.  Do you think that by stopping watering and fertilizing and only misting the leaves and pseudobulbs the bugs may die on their own?  I try to repot every 2 years but maybe that's not soon enough and why the bugs are proliferating.  Advice there as well?

Thanks again and sorry for so many questions.

ANSWER: With regard to your first followup question, there is no set date for plants to go into dormancy.  One of the reasons for this is that most orchids are hybrids which are the result of crossing one species with another or by crossing two hybrids, or by crossing a hybrid with a species. I try to stay away from plants that don't have name tags because I have no way of knowing which species or hybrids are the parents.  Many mass marketers, such as are marketed under the name "Easy Orchids" rarely, if ever, include name tags.  I have found that orchids marketed under the name "Better Grow" often do have name tags.  The reason there is no simple answer to your question is that the species used to create your hybrid orchid come from different parts of the world and different climates.  Most species of dendrobium and cattleya orchids come from areas that have distinct dry seasons.  These dry seasons may be different in different parts of the world, different elevations, etc..  To ascertain the rest period of your plants, water and feed them during active growth until the growth is fully mature and no further growth or flower spikes are evident. It your plant shows no signs of being in growth, treat it as if it is a rest period.

With regard to pests, sow bugs (ie roly polly bugs) live and reproduce in a potting mix that is older and tends to retain moisture in the root zone.  This problem should go away when you repot in fresh, high grade, orchid potting mix. Generally, these don't do major damage on the plant or its roots as they feed on the contents of the potting mix.  Fall is a good time to treat your plants before bringing them indoors.  Use a good systemic insecticide such as "Eight" which is absorbed into plant tissues and kill the sucking insects as they feed on the plant tissues.  It usually is effective for 6-8 weeks.  Most other insecticides are "contact" insecticides which actually kill the insects that it contacts.  These usually require several applications as there are always insects hiding in sheaths, potting mix, etc which will not come into contact with the insecticide.  Most "home remedies" such as isopropyl alcohol or various soaps, neem oil, etc are of the letter type. Remember to protect yourself with gloves, mask, etc and stand upwind when applying any insecticide. For ants. there are a number of remedies such as ant traps orpellets/granules (the latter work there way into the potting mix and can eliminate ants that may have colonized the potting mix.  

With regard to humidity, 40% is a good humidity level.  To increase this for the plants, you might try using a pebble tray. It is simple a tray containg small pebbles and a small amount of water which wet the pebbles.  The pot(s) are then placed on top of the pebbles above the water level to create a microclimate for the plant.

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QUESTION: You recommended a systemic insecticide called 'Eight" but I can't seem to identify this product.  Can you be more specific?  If you cannot recommend a brand can you give me a hint as to the ingredients?

Thank you!

Answer
Corinne, Eight is marketed by Bonide, a marketer of Home and Garden products.  It is available in the midwest at many local garden centers. On line, you can find it at Bestnest.com and a number of other retailers by googling Bonide Eight Insect Control.