Hydrangea plants have beautiful clustered blooms that are available in a variety of colors and shapes. Their stunning flowers provide a great addition to both gardens and floral bouquets. Hydrangeas are popular deciduous shrubs that stand out in landscapes due to their showy flowers. Colors range from frosty whites to vibrant blues and pinks. Caring for hydrangeas is relatively easy once you understand some basics.
1. Planting Your Hydrangea
Hydrangeas will thrive if planted in the right location! Some varieties such as the Oakleaf type get very large and need a good amount of space. Most hydrangeas also prefer part sun/part shade conditions. Ideally, they like morning sun and afternoon shade. Hydrangeas also need porous and moist, well-drained soil. Simple planting instructions include:
- Dig a hole that’s as deep as the root ball and about 2 times as wide.
- Set the plant in the hole and fill it half full with soil. Water.
- After water drains, fill the rest of the hole with soil. Water again thoroughly.
- Add compost to amend poor soil (optional).
- Finish with a layer of mulch to help retain moisture.
Hydrangeas can be planted any time of the year except when the ground is frozen. After planting, keep your hydrangea well watered until it’s established and check for signs of wilting.
2. Pruning Hydrangeas
Many people are confused about when to prune their hydrangeas. Pruning at the wrong time can prevent a hydrangea from producing flowers. There are generally two different types of hydrangeas with respect to pruning – “Old Wood” and “New Wood” bloomers.
Old Wood Bloomers
Hydrangeas that bloom on old wood start developing their bloom buds the summer before the current season. Prune them only after they bloom in the summer! Pruning them in fall or later will remove the bloom buds for next year and they won’t flower. However, feel free to deadhead the plant and remove old blooms after they fade. Cut them off with a short stem so that you don’t disturb any new buds. You can also remove dead or weak stems by cutting them to the ground.
Popular types of “Old Wood” bloomers include:
- Hydrangea macrophylla – Mophead, Big Leaf and Lacecap
- Hydrangea quercifolia – Snow Queen, Ice Crystal, and Ruby Slippers
- Hydrangea serrata – Bluebird and Kiyosumi
New Wood Bloomers
The “New Wood” bloomers set flower buds on the current season’s wood. They can be pruned in fall or winter which makes the timing of pruning less critical. You can remove dead stems and prune to retain the shape of the plant. Typical varieties of “New Wood” bloomers include:
- Hydrangea paniculata – Pee Gee, Limielight, Pinky Winky, Little Quick Fire and Lavalamp Candelabra
- Hydrangea arborescens – Annabelle, Invincibelle and Haas Halo
Old and New Wood Bloomers
‘Endless Summer’ is a new variety of big leaf hydrangea that produces flowers on old and new wood. It starts blooming in early spring and produces flowers continuously all summer long. You can prune ‘Endless Summer’ any time of the year and it should still flower. This plant is better for cold climates since it will flower on new wood even if the old wood suffers cold damage. Tuff Stuff (hydrangea serrrata) is also a variety that blooms on old and new wood.
One final note about pruning – it’s a good idea to remove about one-third of the oldest stems each year to revitalize older hydrangea plants. This will result in fuller and healthier hydrangeas.
3. Altering Hydrangea Color
You can change the color of Bigleaf hydrangeas (H. macrophylla) by modifying the soil pH. This includes the Mophead and Lacecap types. Acidic soil (pH less than 5.5) will produce blue flowers and more alkaline soil will produce pink flowers. Sprinkle aluminum sulfate over the soil to make it more acidic and lime to make it more alkaline.
Altering the color of your hydrangea takes time so don’t expect instant results. It may take months! Also, it’s easier to change blue flowers to pink than pink to blue. You may get purple flowers if the soil is slightly acidic or neutral (pH of 6 to 7). Sometimes a combination of blue, pink and purple flowers will bloom on the same plant! White flowers aren’t affected by soil pH so you won’t be able to change their color.
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