From the AOS - Monthly Checklist for July and August

Specialized Topics
Written By David Kirk

The American Orchid Society is a horticultural society that promotes and supports the passion for orchids though education, conservation, and research. This month Bridget shares an article originally by Ned Nash and James Rose, and upcoming programs from the AOS.

By Bridget Kerans, American Orchid Society Representative

Monthly Checklist for July and August

Cattleya - Cattleyas this month require careful attention to their watering and fertilizing needs owing to characteristically high temperatures. Evaporative cooling is a must in areas of the country where it is effective. Where it is not (the more humid regions), care needs to be paid to proper venting to keep temperatures within reason. Bottom vents in conjunction with top vents provide enough rising airflow to help keep plants cool. Increased air flow lessens humidity and dries plants out more quickly, necessitating more frequent damping down and watering, in areas where high humidity is not a problem. Higher light and heat indicate more fertilizer. The growths your plants are making now are the source of this autumn, winter and spring's blooms, so applying adequate fertilizer this month is the best way to ensure future blooms. Higher temperatures and humidity may also lead to fungal or bacterial rot problems, so it is important to closely observe your plants for any early indication of problems. Pests are also at a high point this month for the same reason.

Paphiopedilum - Cooling and air circulation are especially critical in these two months to prevent stress and avoid disease problems. Watering needs to be closely monitored to ensure that plants do not dry out. Warmer-growing hybrids will be at the peak of their blooming, with attention needing to be paid to staking of spikes. Look for water lodging in growths, which can rot emerging spikes and lead to the loss of the entire growth.

Phalaenopsis - Most, if not all, potting should be complete by now. This month and next are when these plants achieve their maximum growth. This growth will be that from which they set their spikes for the coming season. The more leaves the plants grow, the better potential for spiking will be realized. Growers in cooler areas such as the Pacific coast have the advantage this month, should they choose, of cooling for early season spikes. Lots of heat and light call for liberal applications of water and fertilizer.
 

Cymbidium - Summer can be the most rewarding season for cymbidiums. Growths should be coming strong now. The leaves of the new growths are best when they are broad and fairly stiff. The color should be a light green to nearly yellow. Early flowering varieties should be showing flower spikes, so move the plants into a cooler area with lower light. For mid-season varieties, lower the dosage of nitrogen to assist in spike initiation.
 

Aliceara Diana Dunn 'Newberry'

High-elevation Plants - For cooler-growing plants, such as masdevallias, other pleurothallids and the like, the next few months will be a challenge. During the hottest times, keep your plants more shaded and be sure to keep the humidity level much higher. Do not let plants dry out. Delay any potting until the weather cools.

 

Oncidium intergenerics - Many of the intergeneric crosses with oncidiums, will be blooming now. Take special care to train the spikes for best floral display. Keep plants under fairly shady conditions. Watch for snails and slugs.
 

The Philippine species, Vanda sanderiana, rewards growers with massive heads of flowers at the end of summer.

Vandaceous - Plants will be growing quickly now and really enjoying the hot humid days so similar to their native habitat. Watch for pests though, as many of these also enjoy the same conditions as the plants. Check flower spikes so that they can extend unimpeded for the best flower presentation later.

The AOS thanks Ned Nash and James Rose for this essay. Updated to current genera names (July 2024).

Upcoming AOS Webinars

**OPEN TO ALL**

Greenhouse Chat July 2025

Ron McHatton

Wednesday, July 2nd, 2025, 8:30 PM – 9:30 PM EDT (7:30 PM – 8:30 PM, CST)

Join Dr. Ron McHatton as he answers your questions about all things orchids. Please send your question and pictures to Sandra Svoboda at greenhousechat@aos.org by June 30, 2005.

**MEMBERS ONLY**

Orchids Under Lights─Greenhouse Not Required

Sarah Hurdel

Tuesday, July 8th, 2025, 5:30 PM - 6:30 PM EDT (4:30 PM – 5:30 PM CST)

Join Sarah Hurdel as she discusses growing orchids under lights.

In the Next Issue of ORCHIDS Magazine

Coming in our July 2025 issue

  • Tom's Monthly Checklist by Thomas Mirenda

  • Why Will It Not Bloom, Part 3: Cymbidium by Ron McHatton

  • For the Novice - Sunburn or Something Else? by Sue Bottom

  • My Favorite Orchid - Vanda garayi by Barb Schmidt

  • Collector's Item - Lepanthes guatemalensis by Judith Rapacz-Hasler

  • Orchids Illustrated - Franz Paula von Schrank – Polymath by Wesley Higgins and Peggy Alrich

  • A Dresden rehearsal; Preparing for the 24th World Orchid Conference, Dresden, Germany 26th to 29th March 2026 - Clare and Johan Hermans

  • Dendrobium and its Relatives Part 11: Dendrobium section Holochrysa by Jim Cootes

  • Cattleya violacea Part 2 by Juraj Kojš

 

David Kirk
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From the AOS - Orchid Fertilizer