August 2020
By Debbie Lestz Teahan

Summer Grooming and Care
This is the season Dahlia enthusiasts wait for all year long. The plants are growing tall and every day new buds and flowers appear. It’s what makes all the hard work worth it!

These tips are based on information from the Rochester Dahlia Society, American Dahlia Society, and my own experience. It is often said that if you ask ten Dahlia growers the same question, you will get ten different answers! The tips here are basic Dahlia growing methods preferred by most.

Dahlias need plenty of water during the summer, at least one inch a week. Drip irrigation is the preferred method, as it will keep water off the leaves and moisture will soak down to the roots. It also helps prevent fungal and mildew problems. Watering by hand is not recommended. My plants are watered every other day for 45 minutes to an hour with drip irrigation. Mulching is suggested to help retain moisture but do not let the mulch touch the stem. Leave a circle around the stem. Dahlias will rot if over watered.
Dahlias are vigorous healthy plants and respond well to organic care. The main grooming activity is “Disbudding”, which encourages bigger, hardier flowers. Dahlias almost always produce three buds at the end of a branch along with two more buds at the next lower pair of leaves. With your fingers or garden scissors, pinch off two outer buds of the three at the end of the branch and the two at the next lower pair of leaves. This saves only one flower out of five, but it will be healthy and large. Even if you are not entering flowers in a show, it is important to groom plants for the best flowers possible. Dahlias produce multiple branches with numerous buds. You will not be lacking in gorgeous blooms by pinching buds. Disbud in the morning or evening when plants are full of moisture. Cut off fading blooms as you would for other flowers. By doing so, Dahlias will bloom continuously up to the first frost. I like to dead head by bringing cuttings inside to fill vases with these incredible flowers.

Staking and Tying
Dahlias need to be staked and then tied several times as they grow taller. Put stakes in the ground when tubers are planted in the soil and perform the first tie once the plant is tall enough. Dahlias need this support and will fall over or break branches if not supported well enough. Some growers set up fencing and tie the plants from top to bottom. There is no wrong way as long as your Dahlias are well supported.

It is particularly important to fertilize often during the summer. The plant is now sending out feeder roots and receives nutrients from those rather than from the tuber. Additional nutrition is required and any low nitrogen fertilizer, either granular or liquid will do. Fertilize every 2-3 weeks and the difference is amazing. Your plants grow larger and produce more blooms. The heat and dry conditions this year make this care especially important. Sprinkling Epsom salts is also recommended to add more nutrients. Liquid kelp is a great way to feed the leaves, too. Stop all fertilizing in late August or early September, so the tubers start storing food and energy for their long winter nap.
Fighting Pests
Pests can attack Dahlias and this is one of those cases where every Dahlia grower has their preferred method to keep their plants safe. Just like all plants we grow, keeping your plants healthy will enable them to better fight off pests and problems. Slugs are a common eater of Dahlia leaves. They can strip a plant as
effectively as rabbits. I’ve fought slugs before and this year for the first time, am fighting hungry rabbits. It is unbelievable how similar the damage looks. Pick slugs off by hand or sprinkle a slug control product around the base of the plants. It will also control snails.

Insecticidal soap is a way to reduce some of the pests that eat leaves. When spraying, do not forget the underside of the leaves. Another leaf eater is the cutworm. Other pests suck sap from the Dahlia and include aphids, thrips, mites, and leafhoppers. There are also numerous small flies and bugs who seek to snack on your plants. Neem oil is an organic method of controlling pests and also helps prevent fungal diseases. Some growers prefer systemic insecticides and herbicides. Whatever you decide to use, read the label and follow the instructions carefully.

Above all, enjoy your blooms and take time to marvel at the majesty that is a Dahlia. I was enthralled and completely hooked after seeing a Dahlia bouquet for the first time. The joy only increases every year.

For more information you can go to or
The Latest on Unsolicited Seed Package Shipping
USDA APHIS Update August 3, 2020.

The U.S. Department of Agriculture (USDA) urges anyone who receives an unsolicited package of seeds to mail those seeds to the location listed below for your state. If more than one location is listed for your state, please select the location closest to your residence.

Instructions for Mailing Seed Packets:
  • Place the unopened seed packet and any packaging, including the mailing label in a mailing envelope. If the seed packets are open, first place the seeds and their packaging into a zip-lock bag, seal it, and then place everything into a mailing envelope.
  • Please include your name, address, and phone number so that a State or Federal agriculture official can contact you for additional information, if needed.
  • In some cases, you may also submit your information online. Instructions are provided below if that is an option in your state.

If you are unable to mail the package to one of the locations below, please contact your APHIS State plant health director to arrange a no-contact pick up or to determine a convenient drop-off location. 

New York:
JFK Plant Inspection Station
Attn: Supervisor Erich Glasgow
230-59 Rockaway Boulevard
Building C, Suite 100, Room
109 Springfield Gardens, NY 11413

Check in With Your Trees (from NYS DEC)
If you have trees on your street or in your yard, this is your friendly reminder to do a seasonal check-in.
What You May See Now
Tar Spot
Noticing black spots on your maple leaves this summer? Your maple tree may have tar spot - but fear not! Tar spot is a fungal disease that resembles splotches of tar on leaf surfaces, but it is mostly just a cosmetic nuisance. Heavy infections may cause early leaf drop, but the fungus does not cause long-term damage to the tree.The fungus can overwinter in leaf litter in your yard. If you would like to prevent tar spot in your trees for next year, be sure to remove all leaf litter when the leaves fall in autumn.
Oak Wilt
In July and August, keep a look out for signs of oak wilt disease. Oak wilt is a fungal disease that affects both red and white oaks, but red oaks (pointy leaf tips) often die much faster than white oaks (rounded leaf tips).

Photo: Leaves from a red oak tree infected with oak wilt. Infected red oak trees lose all or most of their leaves very quickly in July or August.
Gardening Helpline at Your Service
When plant, insect and wildlife problems happen in the garden, who can home gardeners call? A team of trained Master Gardeners are available to help answer gardening and pest questions, and solve problems using current research-based information.

By calling the helpline, you’ll find yourself in contact with someone who will help identify the cause of your problem, or give an answer to your question using Cornell’s experience and research knowledge. If the issue is addressed in one of our many factsheets, it will be sent to you for your reference.

Contact us: (585) 753-2555 or

Gardening Helpline Hours:
April – October: Monday - Friday, 9 AM - 12 PM       
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The world’s longest-living people share this hobby—why studies say it can help add years to your life
What do you know, it's gardening!

Reasons why gardening could help you live longer:
  • It gets you into nature
  • It's good exercise
  • You'll eat what you grow
  • It exercises your mind, while also relieving stress

Upcoming Zoom Events
Presented by Master Gardeners (MGs). Registration Required.
Be on the lookout for your confirmation email with the Zoom link to access the class!
Monarch Butterflies
Tuesday, August 18, 7 PM - 8 PM
Hosted by Webster Public Library
Register Here (FREE)
The population of Monarch butterflies has plummeted and there are concerns that they could become extinct. This presentation will discuss the fascinating life cycle of these insects, the multiple threats to their survival, and what upstate New York gardeners can do to help their survival.

Presented by MG John Nelson.
Gardening with Native Plants
Thursday, August 20, 7 PM - 8 PM
Hosted by Brockport-Seymour Library
Register Here (FREE)
Gardening with native plants helps pollinators and other native species! Learn about the many benefits of including native plants in the garden. Suggestions for native plants for sun, shade, wet and dry locations will be provided.

Presented by MG John Nelson.
Poisonous Plants in Ornamental Gardens
Wednesday, August 26, 1 PM - 2 PM
Hosted by Central Library of Rochester & Monroe County
Register Here (FREE)
Many of our favorite ornamental garden plants are poisonous and some have fascinating histories! 

You may be surprised to learn that there are poisonous plants growing in your garden. Join us online for our next gardening workshop and learn about a common shrub whose pollen produces toxic honey, and another called the “Tree of Death!” The speaker will provide some common sense precautions to safely grow these plants in your garden.

Presented by MG John Nelson.
Photo: Manchineel, known as "Tree of Death"
Master Food Preservation Classes
Our colleagues at CCE-Saratoga are offering a series of food preservation classes online. Register for one or all of these FREE classes taught by Diane Whitten, CCE Nutrition Educator and Cornell Certified Master Food Preserver. For additional information, contact Diane at

Need help with your garden? Try a Home Site Assessment!
The Cornell Cooperative Extension of Monroe County Master Gardeners offer site assessments of residential properties within Monroe County.

A $75.00 fee provides a one-hour consultation with a team of two CCE-MC Master Gardeners in the areas of plant identification, disease, pest or weed identification. Master Gardeners can offer suggestions on landscape and garden design. If a sample needs to be submitted to the diagnostic lab, a lab fee of between $5 and $20 will be charged.

Master Gardeners can also report on environmental situations limiting the growth of particular plants (soil or light conditions). They will also identify situations that might require professional follow-up such as tree care or removal and can provide a list of companies.

Visits scheduled April through October. Call to schedule your home site assessment now! 585-753-2558
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