Hydrangea Care

Various hydrangea plants in different colors are displayed with informational tags under a "Hydrangea Care" sign.

By Richard Flowers, ACCNP-Green Thumb Nursery-Ventura

Your favorite Green Thumb Nursery carries an assortment of beautiful selections and types of Hydrangeas from greenhouse grown subjects that are forced to bloom when other hydrangeas do not. Landscape hydrangeas on the other hand are grown outside and are hardier than greenhouse grown types. Greenhouse grown Hydrangeas provide you with eye popping color of white, blue, purple, pink, and sometimes red. These types of Hydrangeas are great as floral gifts. These Hydrangeas are more temperamental if grown outside in areas, but give them the benefit of the doubt, they will adjust to the outdoor conditions with time but at first they may look a little unattractive. The landscape grown hydrangeas are adjusted to the outdoor conditions and and take less shade than their greenhouse grown counterparts. Hydrangea plants boost large globes of flowers that cover the plant inspiring to summer surrounded by lush dark green leaves. While some landscape grown Hydrangeas may not be in bloom just yet, or starting to, just wait a few weeks or so and they will delight you with wonderful flowers. Although their appearance may seem high maintenance, with the right conditions and care, Hydrangeas are actually fairly easy to grow.

After waking up from their winter rest, Hydrangeas (sometimes called Hortensia) are starting to show their luxury once again. Hydrangeas work well when planted with ferns, Azaleas, Begonias, Impatiens, grasses, Viburnum, and Holly. Believe it or not they do best in the same soil.

I want to provide you some helpful concepts on how to care for your beautiful hydrangeas. 

Fertilizer/Soil/Mulch: Hydrangeas are acid loving plants. These plants also love lots of mulch. I find  that when you apply a 3-4 inch layer of mulch it not only  improves the soil as It breaks down, reduces water evaporation, cools the roots, keeps unsightly weeds at bay, but also brings out the dark green leaves and beautiful flowers they produce, making them appear more vibrant. When applying mulch, be sure to keep it away from the main stem. Because our soil is mainly alkaline you should incorporate organic soil amendments and fertilizers into your care routine of these prized possessions. When fertilizing after bloom it is best to do so in spring or early summer. Use a granular, slow-release fertilizer with a high percentage of phosphorus. Make sure you don’t use too much nitrogen fertilizer as this can cause them to grow big green leaves and stunt bloom. A well balanced  fertilizer is usually adequate (look for something that says all purpose fertilizer or one that has all the 3 numbers( NPK) the same. You can even use a fertilizer geared for acid loving plants such as Cotton Seed Meal or Azalea Camelia ferilizer. Green Thumb carries both organic and non organic fertilizers available. Simply apply widely around the drip line of the branches instead of the base of the plant, and cover lightly in soil. Many times hydrangeas need extra supplements of fertilizer to help acidify the soil. Apply fertilizer based on your specific Hydrangea. Each variety has different needs and will benefit from different application timing. The best way to determine your fertility needs is by using a soil test. Simply measure your soil ph with a soil ph test kit . Big leaf Hydrangeas need several light fertilizer applications in March, May and June, while Oak-leaf and Panicle Hydrangeas do best with two applications in April and June. Smooth Hydrangea plants only need fertilization once, in late winter.

Many times when you come into Green thumb Nursery you see hydrangeas  already in bloom ether pink or blue. Have you ever wondered how people get those colors? Hydrangeas are unique in that you can control their color. But keep in mind, not all Hydrangea types are capable of color adjustments. Bigleaf Hydrangeas, react to changes in soil PH. PH is how basic or acid your soil is . A low soil pH (acid soil) allows hydrangeas to absorb aluminum, which turns the flowers a beautiful blue color. To increase blue Hydrangea flowers, lower your soil pH by adding sulfur or peat moss to the soil. You can also add additional aluminum sulfate to your soil throughout the growing season. For pink blooms, your soil must be alkaline (pH higher than 7), which can be achieved by adding lime (not the fruit though!) Or super phosphate to the soil. Our in ground soils tend to be more alkaline in nature so add lime in smaller amounts based on soil  test readings. The soil Ph Test device can be purchased at any of the Green Thumbs and can help you accurately adjust your soils ph for  your Hydrangeas color. No matter what adjustments you’ve made, all hydrangeas will naturally fade in the fall. Don’t worry – the plant will showcase fresh, colorful blooms again in the spring. White hydrangeas do not need color treatment, they stay white. 

Hydrangeas grow well in soil containing an abundance of organic material and excellent soil drainage. I suggest to use a compost like Azalea and Camellia mix or Acid Planting Mix. Which can be used for both in ground or container applications. If you have heavy clay soil like many of us do, consider mixing in plenty of compost prior to planting to improve soil quality. For a sandy  soil  you may want to use Kelloggs Gro Mulch as a soil amendment.

Water: The name Hydrangea in itself tells you something what they like- water. Lets break down what the name actually means. The meaning of Hydrangea stems from the Greek words for water which is hydros and jar which is angea. It was given the name because of its shape resembling an ancient water pitcher. With their big leaves, they transpire lots of water. How fitting, since Hydrangeas require constant moisture to stay happy, healthy and blooming.

Water at a rate of 1 inch per week throughout the growing season which is usually March  through Mid June. Deeply water 3 times a week to encourage root growth. I recommend to water newly planted Hydrangeas every one to two days (or more during extreme heat and drought conditions). Once established, water when the top inch of soil is dry to the touch. I recommend to keep the soil around them moist, but not wet. Overwatering can reduce flower production. Hydrangeas like moist soil, they cannot tolerate being waterlogged. Soggy, poor draining soils can cause root rot in just a few weeks, your Hydrangeas can quickly die. The most popular Hydrangea the Big Leaf  Hydrangea (these are the ones that have flowers that look like pompoms or mop heads) require more water, but all varieties benefit from consistent moisture. Regular watering in the morning can help prevent wilting. If they perk back up once the day begins to cool, you don’t need to worry. It’s better to have a little mid-day wilting than to overwater and drown them. Oftentimes when very warm weather occurs they may start to wilt, when this occurs it is advised to water  them as soon as possible to prevent any further damage to the plant tissue like browning leaves, flowers, and stems. When watering, it is very important avoid watering the leaves as this may cause the growth of Powdery Mildew or other funguses. Instead water the soil only. Using a soaker hose or drip irrigation to water deeply and keep moisture off the flowers and leaves is an effective way to water. Hydrangeas do not like overhead watering  which includes rain, fog or mist from the  weather. If you do happen to overheard water do so in the early morning so the  plant tissue has a chance to dry off  provided  their is no overcast and cloudy day ahead. Moisture on the tissues of the plant for a prolonged period of time  cause fungal growth. Watering in the morning will help prevent hydrangeas from wilting during hot days.

Containers: Hydrangeas are not exclusive to growing in the ground, they do wonderful in containers. Plants in containers need more frequent water and fertilizer applications than ones planted in the ground. When selecting a container be sure the diameter is 2 -3 times as large as the root ball of the plant and make sure when planting you plant at the same level the root ball is and fill the container with acid mix up to the line in the pot where the color or ridge is not all  the way up to the rim or the container. Look for non-porous containers to help hold the consistent moisture level require by hydrangeas. Drainage holes will allow excess water to drain properly. Be sure to be more conscientious about watering, because plants in containers dry out quicker due to their limited area.

When/Where To Plant:  If you are a gardener like I am, you are aware that the best time to plant Hydrangeas is during the fall right before they go dormant, however good luck finding decent looking plants during that time of year. When spring is in full swing and they have waken up form their winter rest and the weather starts to warm up is more appropriate to find these beauties. During spring they are coming into their own, looking healthier, more lush, and more selection to choose from. Hydrangeas do not like hot, drying  temperatures, and low humidity, with that being said, the best time of day to plant is early morning or in the evening because the cooler parts of the day offer protection against heat stress. Place your Hydrangea where it gets warm morning sun, but away  from the heat of the afternoon. The best place to plant them is in a sheltered location with sunny mornings and shady afternoons. Under the canopy of a tree (but not  directly underneath trees, which can lead to competition for water and nutrients) , a porch or over hang is ideal. Where ever you have ferns, Azaleas, Begonias, Camellias, and Impatiens is where Hydrangeas will be happy. You often find them on the north side of your home. 

The most popular type of Hydrangea is Hydrangea macrophylla or commonly known as Big Leaf  or Mophead Hydrangea. This type of hydrangea grows more round.  Mophead Hydrangea  prefers part sun while  Panicle Hydrangeas ( Hydrangea paniculata) can actually tolerate more sun. Panicle hydrangeas sports a flower that is more cone shaped and grows more up right rather than round, like Big Leaf Hydrangea. Their are also Lace Cap Hydrangeas that could spark your interest.  Hydrangeas grow fast and attract butterflies. They will not bloom or grow poorly in heavy shade. It isn’t so much a question if  they prefer sun or shade, but rather more of a question of how much sun do Hydrangeas need? In hot interior areas it is best  to provide them more shade, while in cooler coastal regions provide more sunlight. With all that being said, they like morning sun, but do not do well if they’re in direct, hot afternoon sun. Partial shade in the later parts of the day is ideal. Place your hydrangeas in a wind sheltered area because high winds can rip and damage leaves and destroy the flowers and dry out your plants. Your main goal when you’re planting them is to avoid planting in the heat of the summer or during the hottest time of day . 

Hydrangeas do not like to be crowded amongst other plants, buildings or objects. They like plenty of space. Poor air flow flow around each plant is an invitation for funguses like Powdery Mildew. Powdery Mildew and other funguses makes the plants look unsightly and grow poor. A good rule of thumb is to have enough space where you could walk around each plant without  touching it.

General Care : In addition to Powdery Mildew, Hydrangeas are also susceptible to a number of other fungal diseases especially in cool coastal areas as well as inland locations. Many plant diseases have similar prevention methods. Organically, it is always a good idea to clean up your gardens of  any diseased leaves, flowers or stems that fall on the soil they should be cleaned up as soon as possible. Any diseased areas on your plant should be removed, after doing so, disinfect your pruning tools with a solution of 10 to 1 bleach and water or use disinfecting wipes. It is also a good idea to have clean rakes, shovels and weeders. The idea is to reduce the spread of the fungus spores in the soil and not reinfect or make your plants worse. Remove weeds because believe it or not weeds do harbor diseases. Keeping  your Hydrangeas vigorous, strong, properly watered, right soil, fertilizer, and proper location will go a long way because a weakened plant is more susceptible to disease. Regularly inspect your garden for abnormalities and address the issue promptly. Sometimes you may need to use a fungicide as a last resort. For organic control consider Neem Oil,  if you prefer something that is not organic use Cooper Fungicide. If your plant exhibits the signs of powdery mildew or any other plant disease, it is wise to bring fresh samples into your favorite Green Thumb Nursery and one of our experts will verify the issue and provide solutions that is the most effective. Be sure to place the samples in a sealed plastic bag so it does not contaminate other plants. Always read, follow, and understand all label directions. 

Deadheading and Pruning : If  your Hydrangea flowers start to turn brown or look shriveled after blooming, cut them off with clean, sharp pruners to encourage new, healthy growth, this is called deadheading. Deadheading can make your hydrangeas more attractive and bloom more. You don’t have to wait until the flower wilts – hydrangeas make excellent cut flowers. Leave those early fall blooms in place to fade on their own. In some cases it is  not necessary to remove dead Hydrangea blooms. Deadheading is not technically “pruning.”  ( Pruning will be discussed shortly). Some gardeners like to leave the spent flowers on their hydrangeas for seasonal interest. If you do choose to deadhead, remember to leave the flowers on as long as possible. This is because many will change color as they age. Deadheading involves cutting right above the set of leaves just below the spent flower. Avoid cutting below the first set of leaves; you don’t want to accidentally cut off emerging buds. Hydrangeas make wonderful dried and cut flowers.

When pruning Hydrangeas that bloom on old wood like  big leaf (Mophead hydrangeas  do so  after the flowers fade. Trim them back to a set of healthy buds , in late summer, before the plant begins to go dormant. Prune off 20%. Prune off crossing branches and  lace out the plant for optimal air circulation. Do not prune after the first week of August. When pruning in the fall or very early spring only remove dead wood. To prune, cut one or two of the oldest stems down to the base to encourage branching and fullness. To prune other Hydrangeas like Oak Leaf, panicle, and smooth hydrangeas that blossom on the current (new growth) season’s wood, do so in the late winter when the plant is dormant before bloom. As a general rule, prune only dead branches. When cutting stems, prune just higher than a pair of leaves . All hydrangeas can be pruned to maintain size and shape. Prune dead and weak stems as needed. 

I hope you find this information about Hydrangea care helpful for you. Head down to your favorite Green Thumb Nursery, we have lots of cool and unique plants and garden accessories for you to check out. 

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