Everything You Need to Know About
Heavenly Hydrangeas!

According to the United States National Arboretum, there are approximately 23 species of Hydrangea. Only five of these are cultivated in the United States. These species are Anomala, Arborescens, macrophylla, Paniculata and Quercifolia. Depending on the species, hydrangeas can be planted in just about any location. No matter what species you choose, you can guarantee that the Hydrangea will provide long lasting blooms in the garden.

Hydrangea arborescens

The arborescens, or the smooth hydrangea is native to moist or rocky wooded slopes, ravines, stream banks and bluff bases in our area. The grayish brown stems have serrated, dark green leaves with pale green undersides. In the fall the leaves turn yellow. Tiny white flowers bloom From late spring to mid summer flattened hairy clusters. The most common varieties are Annabelle and Incrediball.

Arborescens Care and Growing Tips

  • 
Soil – All arborescens prefer to be planted in moist, well drained soil. Adding organic matter to soil will help with drainage.
  • Water – They are intolerant of drought and should be watered weekly to establish the plant and promote a good root system. When the temperatures soar and we are not getting rain, be sure to give them additional water. Adding a layer of mulch around the base of the plant will help keep the soil moist and control weeds.
  • Light – Arborescens do best in part shade to part sun. The bloom production will be heavier if given a bit more morning light or dappled afternoon shade.
  • Fertilizing – Fertilize in the spring and then again in late summer, no later than August. We recommend using organics as they are better for the soil and are non burning. We will be happy to help you select the proper fertilizers.
  • Pruning — Arborescens blooms on new wood. The entire shrub can be cut back 1-2′ above ground in late winter each year to revitalize it and to encourage vigorous stem growth and best form.

 

Hydrangea macrophylla

Macrophylla, or commonly known as Mopheads, Bigleaf or Lacecaps are the most popular hydrangeas grown in home gardens and landscapes. The blooms can be blue, pink or shades of purple, depending on the pH (acidity) of the soil. Some can even be white. Some varieties of macrophyllas bloom on old wood, producing one flush of blooms per season. Other varieties bloom on both old and new wood. This means they are rebloomers, typically blooming from late spring until fall.

Lacecap Hydrangea

Lacecap Hydrangea

Endless Summer – Hydrangea macrophylla

Endless Summer – Hydrangea macrophylla

Macrophylla Care and Growing Tips


  • Soil – All macrophyllas prefer to be planted in moist, well drained soil. Adding organic matter to soil will help with drainage.
  • Water – Macrophyllas do not like to be dry, but not overly wet. They should be watered weekly to establish the plant and promote a good root system. When the temperatures soar and we are not getting rain, be sure to give them additional water. Adding a layer of mulch around the base of the plant will help keep the soil moist and control weeds.
  • Light – Macrophyllas do best in part shade to shade. The bloom production will be heavier if given a bit more morning light or dappled afternoon shade.
  • Color – To encourage blue flowers, the pH need to be lowered. We recommend using Espoma Organic  Soil Acidifier to the soil several times per year, beginning in fall and repeating before leaves emerge in spring and before the buds set. To encourage pink flowers the pH needs to be raised. We recommend adding Garden Lime. Some hydrangeas are not affected by the addition of these products and are noted as such.
  • Pruning Hydrangeas that bloom on old wood — The flower buds are set after flowering on the old limbs for the following spring. These varieties should only be pruned after flowering. These varieties bloom in the summer. Remove dead limbs as well as branches that are crossing over each other, or rubbing each other. Rubbing can create entry point for insects and disease. The interior of the plant can be thinned a bit to open it to more light and air.
  • Pruning Reblooming hydrangeas, that bloom on both old and new wood — Prune in early spring. Remove dead limbs as well as branches that are crossing over each other. The interior of the plant can be thinned a bit to open it to more light and air. Removing the spent (dead) flowers will encourage reblooming.
  • Fertilizing – Fertilize in the spring and then again in late summer, no later than August. We recommend using organics as they are better for the soil and are non burning. We will be happy to help you select the proper fertilizers.

 

Hydrangea paniculata or Panicle Hydrangea

Hydrangea paniculata

Limelight – Hydrangea paniculata

This is the most cold hardy member of the hydrangea family and is a reliable grower in the St. Louis area. The paniculata is native to Asia, and it grows 1-15’ tall. It has large creamy-white flowers, which grow on 6-18” long panicles, that bloom in mid-summer. As the flowers mature, some varieties may turn pink or some green. These shrubs are commonly pruned into a tree form. They are urban tolerant plants holding up well to pollution. The soil pH does not affect the color.

Care and Growing Tips


  • Soil – Plant in rich, well drained soil amended with organic matter.
  • Water – They should be watered weekly to establish the plant and promote a good root system. When the temperatures soar and we are not getting rain, be sure to give them additional water. Adding a layer of mulch around the base of the plant will help keep the soil moist and control weeds. Once established they will tolerate some drought.
  • Light – Panicle hydrangea grows best in full sun to part shade.
  • Fertilizing – Feed the plant in early spring, just before new leaves begin to bud and again in summer when the flowers bloom. We recommend using organics as they are better for the soil and are non burning. We will be happy to help you select the proper fertilizers.
  • Pruning – Paniculatas bloom on new growth and should be pruned in late winter or early spring before they flush out. You can cut it back close to the ground or, if you want slightly taller plants, cut it back to one to three feet. Make sure to remove the dead limbs and branches that are crossing, or rubbing each other. Rubbing can create entry point for insects and disease. Larger flower panicles can be obtained by thinning the plants to 5-10 primary shoots.

Hydrangea serrata – Mountain Hydrangea or Tea of Heaven

This hydrangea is similar to a macrophylla except it is a smaller more compact shrub with smaller flowers and leaves. It was formerly listed and sold as Hydrangea macrophylla var. serrata. It is native to moist woodland mountain valleys in Japan. It is a deciduous shrub with a rounded habit. It generally features serrated, oval shaped green leaves, and long-blooming summer flowers. The leaves can be used to make a sweet tea, hence the sometimes used common name.

Care and Growing Tips

  • Soil – Plant in rich, well drained soil amended with organic matter.
  • Water – They should be watered weekly to establish the plant and promote a good root system. When the temperatures soar and we are not getting rain, be sure to give them additional water. Adding a layer of mulch around the base of the plant will help keep the soil moist and control weeds. The like moist, not soggy soil conditions.
  • Light and Location – Grows best in part shade. Does best when planted in protected location
  • Color – To encourage blue flowers, the pH need to be lowered. We recommend using Espoma Organic Traditions® Soil Acidifier to the soil several times per year, beginning in fall and repeating before leaves emerge in spring and before the buds set. To encourage pink flowers the pH needs to be raised. We recommend adding Espoma Organic Traditions® Garden Lime. Some hydrangeas are not affected by the addition of these products and are noted as such.
  • Fertilizing – Feed the plant in early spring, just before new leaves begin to bud and again in late summer. We recommend using organics as they are better for the soil and are non burning. We will be happy to help you select the proper fertilizers.
  • Pruning – Serrata blooms on new wood and should be pruned in late winter or early spring. Remove weak or winter damaged stems and dead branches.

Hydrangea anomala – Climbing Hydrangea

The climbing hydrangea is a true self-clinging vine. It will attach itself to walls and can be trained to grow on trellises and fences. They can also be used as a groundcover (if you have the space). It is initially slow growing, but the plant can eventually grow up to 80’ tall! The white, lacecap flowers bloom in early to mid-summer, and the display can be quite spectacular.

Care and Growing Tips

  • Soil – Plant in rich, well drained soil amended with organic matter.
  • Water – They should be watered weekly to establish the plant and promote a good root system. When the temperatures soar and we are not getting rain, be sure to give them additional water. Adding a layer of mulch around the base of the plant will help keep the soil moist and control weeds.
  • Light – Climbing hydrangea grows well in shade, but can also tolerate partial sun here in St. Louis.
  • Pruning – Prune the climbing hydrangea plant in late winter or early spring to remove dead, diseased or damaged branches. Remove dead limbs as well as branches that are crossing over each other, or rubbing each other. Rubbing can create entry point for insects and disease. This woody vine can be pruned to maintain size.
  • Fertilizing – Feed the plant in late winter or early spring, just before new leaves begin to bud and again in summer when the flowers bloom. We recommend using organics as they are better for the soil and are non burning. We will be happy to help you select the proper fertilizers.