Category Archives: Kentucky Shrubs

Creating a Hydrangea Heaven

June is the month with blessings from several varieties of the Hydrangea shrub in the Kentucky garden and landscape! Hydrangeas are the number 2 most popular shrub planted in the home landscape. It grows in zones 3-9 and offers different shapes and colors of blooms for the landscape throughout the growing season. This plant is relatively pest free if planted in the correct place for bloom production.  

Uses of Hydrangeas

Hydrangeas can be used in mass planting, border, and as an accent or specimen plant.

Types of Hydrangeas:

Smooth Hydrangea- Hydrangea arborescens

Oakleaf Hydrangea- Hydrangea quercifolia 

Panicle Hydrangea- Hydrangea paniculata

Bigleaf Hydrangea- Hydrangea macrophylla

Watering

Hydrangea means “water lover” in Greek where “hydra” means water and “angeon” means “vessel”. After planting, water hydrangeas consistently throughout their first year. Even after establishment, hydrangeas will require 1 inch of water per week either by rainfall or irrigation. Additional water may be needed in a sunny or windy location. Make sure to give hydrangeas the proper location based on the type being grown and provide ample amounts of mulch to conserve soil moisture and keep roots cool.

How to Adjust Bigleaf Hydrangea Flower Color

For Bigleaf hydrangea also known as Hydrangea macrophylla, blooms can vary by color from true blue, deep purple, to pink according to the soil’s pH or the availability of aluminum in the soil. For example, in acid soils, aluminum is more available and leads to a blue bloom color. In basic or more alkaline soils, aluminum is found in less amounts and gives a pink bloom color.

Altering soil pH for hydrangea production can take up to 6 months and requires a basic soil test for complete accuracy. Based on soil test recommendations, add powdered or pelletized lime or sulfur in the fall for desired pink or blue blooms for the following summer.

Remontant Hydrangeas

Remontant hydrangeas also referred to as “repeat bloomers” are plants that flower more than once in a single growing season. Some top mophead remontant selections include ‘Blushing Bride’, Endless Summer ‘Bailmer’, ‘Decatur Blue’, and ‘Nantucket Blue’. “Twist-n-Shout’ is the only remontant lacecap type. The bigleaf hydrangea cultivars are more strongly remontant. Make sure to fertilize remontant hydrangeas to help support repeat blooming.

Pruning

In order to prune hydrangea, know the type you have and understand if it blooms on old or new wood.

“Old Wood” refers to previous year’s growth. Hydrangea cultivars with old wood formed the buds the year before.

“New Wood” refers to the current year’s growth. Hydrangea cultivars that bloom on new wood set their buds during the year in which they bloom. 

When is the correct time to prune specific hydrangeas?

Smooth hydrangea blooms on the current year’s growth. For this type, prune back by early March, so plants have time to grow stems and form flower buds.

Oakleaf hydrangea– allow this type to grow in its natural form and prune as little as possible. Oakleaf hydrangea flowers are produced on old wood. If pruning is necessary, finish by the end of July to ensure that there is still time for next year’s flower buds to develop.

For panicle hydrangea, pruning isn’t needed. If you would like to create a neater and tidy appearance and help increase the size and number of blooms, cut the plants back hard to approximately two buds. The blooms will develop on new stems, so make sure that this pruning is performed once plants go dormant through early March. If you desire, panicle type hydrangeas can be trained to a tree form unlike other hydrangeas. Begin training at an early age and requires a stake to help support. To keep the tree form shape, remove branches that develop from the trunk several times throughout the year.

Once bigleaf hydrangea is mature, prune no more than one-third of the older branches to the base of the plant in early spring. Pruning will rejuvenate the plant without a large loss of flowers. To reduce size or for shaping, prune after blooms fade but no later than the end of July.

For more information about growing or caring for hydrangeas, please contact the Warren Co. Extension Office at (270) 842-1681.

Warren County Extension Office Operating Procedures

Several people may be wondering about how to submit samples to the Warren County Extension Office for soil, plant disease, weed, insect, and plant identification services. Read HERE to find out what is needed for each of these services.

Soil Sample Collections

How to Submit Soil Samples:

  1. Drop your collected soil sample in the drop box located in front of the Warren County Extension Office (WCEO) door entrance.
  2. Contact the office at (270) 842-1681 to give office staff general information related to your soil sample.
  3. Please pay with exact change or check which is $7.00 per soil sample.
  4. Results will be mailed to the client after agents review the soil tests. If you have any questions regarding your soil test recommendations, please contact the WCEO.
Plant Disease Samples

How to Submit Plant Disease Samples:

  1. If you suspect a possible plant disease, please submit a fresh plant sample along with 5 photos of the plant in its environment to the Warren County Extension Office.
  2. Samples may be dropped off at our location at 5162 Russellville Road and placed in the drop box which is located in front of the Warren County Extension Office entrance door.
  3. Pictures should show an overview of the planting or field, close-up photos of the parts affected (foliage, trunk, stem, etc.) as well as include general plant information (age of plant, when was the problem first noticed, what percentage is plants affected, and how the plant has been cared for such as watering, fertilizer application, and etc.)
  4. In the event that we need to mail off a plant sample, plant samples must be sent from Monday through Wednesday to ensure freshness.
  5. If you wish to make an appointment or have questions regarding your plant sample, please contact the Warren County Extension Office at (270) 842-1681 first.
Weed Identification- Field, Garden, and Lawn

Weed Identification Sample:

  1. Email photos of the weed to www.warrencountyextension.com/ and tell us where the weed is located such as garden, landscape, lawn, or agriculture field.
  2. A fresh weed sample may be needed if identification can’t be determined through email. Bring sample and place the sample along with client information in the drop box located in front of the WCEO entrance door.
  3. Contact the WCEO at (270) 842-1681 to notify our staff that you have a sample for identification.   
  4. Please tell us the best way to reach you either via phone or email. Agents will get back to you as soon as possible.
Insect Identification Services

Insect Identification:

  1. Email photos of the insect to www.warrencountyextension.com/ and tell us where the insect is located such as garden, home, landscape, lawn, or agriculture field.
  2. An insect sample may be needed if identification can’t be determined via email. Bring the insect sample along with client information to the Warren County Extension Office located at 5162 Russellville Road and leave in the drop box located in front of the entrance door.
  3. Contact the WCEO at (270) 842-1681 to let our staff know that you have a sample for identification.
  4. Please tell us the best way to reach you either via phone or email. Agents will get back to you as soon as possible.
Identifying Plant Samples

Plant Identification:

  • Drop a fresh plant sample at least 12 inches long or longer to the Warren County Extension Office located at 5162 Russellville Road along with client information and leave in the drop box located in front of the WCEO entrance door.
  • Email photos of the plants to www.warrencountyextension.com/ and tell us where the plant is located such as garden, landscape, lawn, or agriculture field. It helps to have as much information on the plant as possible such as bloom color or shape, when the plant blooms, etc.
  • Contact the WCEO at (270) 842-1681 to let our staff know that you have a sample for identification.
  • Please tell us the best way to reach you either via phone or email. Agents will get back to you as soon as possible.

For questions on how to submit samples for identification, please contact the Warren County Extension Service at (270) 842-1681. Please note if you reside in another county to contact your local Extension office to see the best procedure for handling these services.