Winter Wrap UpThe winter of 2013 was particularly difficult for growing Stanhopea. In January the temperature dipped to 31°F (-0.6°C) for only the second time since I have lived in San Diego. This low temperature duration was only for a few hours on one night, but it was unusual in that is was part of a 10 night period in which temperatures ranged from 35-39°F (1.7-3.9°C). This long cold period was particularly difficult for several of the Stanhopea. Some orchids exhibited bacterial growth presenting a few days after the cold snap along with a loss of few leaves after several weeks. In addition to this cold, a very intense hail storm occurred one night and caught me off guard. Most of my Stanhopea collection is sheltered by trees, roof overhangs, and plastic saran; however, a few plants were partially unprotected during this storm and took some damage. If I continue to have these tough winters, it will give me incentive to complete the building of a cool greenhouse to protect the orchid collection better by next year.
|Stanhopea shuttleworthii growing underneath a tree canopy. The plant looks good from a distance (left). However the hail storm damaged the right side of the leaf causing pitting and the cold weather cause bacterial spotting (right)|
Stanhopea Spring Culture Checklist
· Begin watering these species regularly when new growth begins (S. hernandezii, S. insignis, S. jenischiana, S. lietzei, S. maculosa, and S.martiana).
· Begin fertilizing all species regularly once new growth begins. I often reduce the manufacturer’s recommendations in half and fertilize every week or what is known as weakly-weekly. Stanhopea can be rather heavy feeders when they are in active growth.
· Weed baskets to prevent ferns and other plants from taking up space in baskets.
· If you grow Stanhopea in a sunny area or a greenhouse that receives strong sunlight you may want to place saran shade cloth over the growing area in early spring before the sunlight becomes too strong for them. You may also want to consider moving the Stanhopea to another shadier growing area.
· Use of methaldihide products is advised on a weekly basis at this time to prevent slugs from disfiguring new growth and impacting new inflorescence and bud growth. I often use a product called “That’s It” that is a granular form and therefore leaves less residue in the growing media. I am currently testing some more organic methods of slug control.
· In mid to late spring make sure to check for growing inflorescences and ensure that their growth is unimpeded by other plants or the basket. If need be place a plastic label underneath the inflorescence to help direct the growth out of the basket.
· Spring is the second best time to re-pot or re-basket Stanhopea, I think late fall is actually the best time because most Stanhopea have already bloomed and are in a rest period. It is recommended that you allow new growth to begin before you re-basket so that the growth can mature somewhat before you transplant the orchid. This will prevent the new growth from being impacted during the process. Early spring is a good time to transplant because it will also prevent damage to most nascent inflorescences.
· Keep a careful eye out for spider mites as the spring continues and our weather begins to warm and dry out. Small yellow spots on the foliage signal that these pests are active on your Stanhopea. Spray infected areas with an insecticidal soap to kill the pests as soon as possible to prevent them from damaging the plant further and spreading to other orchids.
· You should also be diligent in keeping watch for fungus infections at this time on leaves. Several fungus attack leaves when humidity is high and temperatures are warm. Black or brown spots of leaves and yellowing of leaves in odd patterns are usually the cause of fungus or bacterial infection. Treat with a fungicide or bactericide. I often use Physan 20 to deal with the problems and prevent further damage to the plants.