August Orchid Care Calendar

Compiled by Dixie McCulloch, a longtime KOS member who joined in 1988.

Temperature Range (˚F)DaysNights
Cool house61-9055-61
Intermediate house70-8160-70
Warm houseup to 9070-75

As long as the temperature is high, water should be supplied freely. As the annual growths mature, reduce watering gradually so plants can harden off. Ventilation should be generous as long as temperatures are not too cold. This also helps to harden off the plants. Plants in the warm section, as well as young plants, may require some heat if there is a temperature drop.

You should be fertilizing with 10-30-20 a little more often now to encourage blooming. As the plants mature they do not need the high nitrogen, and the low nitrogen will help to harden them off.

Plants that have flowered during the past few months should be repotted now so that they will still have some warm weather in which to make new growths.

Insects: Warm temperatures cause insect populations to increase. Pay special attention to pest-control management. Observe your plants carefully and spray for both insects and disease when first noticed. If any pest situation gets out of control, you will find yourself battling the adversary for the next several months—just to stay even. Endure the discomforts of patrolling the hot, muggy atmosphere of a greenhouse now in order to maintain healthy orchids this autumn and next winter.

Cattleya: Avoid splashing water on blossoms, and place flowering specimens where air circulation is sufficient to reduce the risk of a Botrytis infection. Continue to fertilize cattleyas frequently. As new growths mature, tie them up carefully to promote upright development of the pseudobulbs. This will maximize growing space and enhance the presentation of future flowers.

Paphiopedilums: Many of these have completed their growing cycle, and the flower buds are beginning to form on the earlier varieties. As buds begin to form, the plants need a little more water. Continue to keep them shaded, except for some filtered early morning sunlight. They will continue to need cool, moist, shady growing conditions to protect the still-tender new foliage.

Phalaenopsis: An abundance of water, filtered light, and fresh air continue to be needed. Any time the plants become dry they tend to lose their basal leaves, and since these leaves are their only means of storing water, the loss can be disastrous. You can start repotting this month and next. Cut back any stems as this time.

Masdevallia: Keep cool and well watered. Give them as much fresh air as you can.

Dendrobiums: A brisk, warm atmosphere helps them continue making rapid growth. The amount of light should be increased gradually so that by the end of the month they are shaded only during the hottest part of the day. Continue to water thoroughly and mist frequently.

The nobile-type dendrobiums are popular everywhere. While many are sold in the warmer latitudes, growers there find this epiphytic orchid a little difficult to flower. In order to promote the gradual shift from active growth (spring to early summer) to the flowering cycle, withhold nitrogen. Experienced growers say that accumulated nitrogen from excessive application through the year may be the reason why these orchids are sometimes reluctant to bloom.

Vandaceous Hybrids: Summer growing conditions are also ideal for hybrids of Aerides, Ascocentrum, Rhynchostylis and Vanda. Feed aggressively and provide high humidity for optimum responses. Try placing a rubber-topped plastic flower tube containing stale beer on a rigid, emerging new root. Rather quickly, the root will consume the beer and utilize its carbohydrate content, providing some remarkable growth responses.

Plants in full sunlight should be fertilized with high nitrogen fertilizer and kept well watered.

Odontoglossum: For Odont. crispum and its hybrids, the end of August and the beginning of September are the best time for repotting.

Outside plants: Check the plants for pests. Aphids and other flying insects tend to be attracted to the plants. You should give them regular spraying to control them. Also, slugs are little pests that like to hang around the plants with the extra watering. You can put the dry baits around on the ground to control them, but not in the pots. Slug and Snail granules work best for that.

Information for these culture calendars are taken from The AOS Bulletin, Orchid Digest, a book Orchids and How to Grow Them by Gloria Jean Sessler and some of my own experiences.

Common uses for Clorox around orchids

Clorox is a trade name for a common household bleach. It consists of about 5% solution of sodium hydrochlorite (so are the cheaper bleaches). It is ideal for cleaning pots benches, and greenhouse walls

Here are some suggested mixes:

  • To clean algae from wood benches, use a 10% solution with water.
  • To rinse your pots, one part Clorox to four parts water. Scrub your pots well before soaking for at least one-half hour in the solution. Wash, dry and rinse again.
  • To sterilize stakes, labels, one part Clorox for every 10 parts water is adequate. Rinse and let dry. If you have quite a lot to clean, change your Clorox frequently.
  • Some growers use a mild solution of Clorox (one cup in a bucket of water) to dip their plants in for several seconds when repotting.