Hydrangeas

Macrophylla (aka French Hydrangea, Bigleaf Hydrangea)

This is probably the most popular species and it is what most people think about when hydrangeas are mentioned. These shrubs have been grown for centuries in American gardens and are often still standing at old home sites where many other plants bit the dust long ago. They are easy to grow, very adaptable to light and soil variations and provide remarkable color (especially the highly sought after blue) in the garden. The flowers are long-lasting and make excellent cut flowers for arrangements or drying.

Flowers in this group come in two types - mopheads (like the one shown in the photo to the right) and lacecaps (see examples in the photos below). This section also includes a sub-species of macrophylla called serrata. The Japanese refer to these plants as "mountain hydrangeas" because they originate in the mountainous areas on the islands of Japan. These hydrangeas are smaller in stature (seldom exceeding five feet) and have smaller leaves and delicate lacecap flowers. It is very hard (at least for me) to distinguish a lacecap belonging to the macrophylla or the serrata group.

Culture

Hydrangeas are moisture loving plants and will languish in hard soils and full sun. They will flourish in moist, well-drained soils that have been enriched with organic materials.

Site Selection - Because these plants demand moisture, shade is welcome, especially during the middle of the day. Some morning and late afternoon sun with shade or partial shade during the hottest part of the day is ideal. Good locations for hydrangeas include the east and north sides of buildings, woodland areas (or the fringes of woodland areas) or in areas with trees that provide high shade.

Planting - Dig a generous hole, wider than the root ball and add compost, aged manure, leaves, peat moss, etc. to the planting mix. Position the plant so that an inch of the root ball sits above the soil line, fill in with your native soil that has been amended and water well. Surround the plant with 1-2 inches of mulch - leaves and pine needles are excellent choices.

Fertilizing - should be done twice yearly - in late winter or early spring and then again after flowering in late summer. Do not fertilize after August. I use a general 10-10-10 granular fertilizer which I sprinkle around the base of each plant. Liquid fertilizers can also be used and are especially recommended if your plant is suffering from chlorosis (yellowing leaves). Always follow the rules on the fertilizer label and don't over-do it. Too much fertilizer can be harmful and can result in excessive green growth and fewer flowers.

Pruning - The topic of pruning is justifiably confusing for gardeners. The fact is no pruning at all is better than going out into the garden and getting happy with the pruners! Hydrangeas usually will thrive and bloom with no pruning at all, except for removing dead limbs and flower heads. However, after 4 or 5 years, a shrub may become too large, straggly or produce fewer flowers. At this point, pruning is advisable.

Flowers form on new growth growing from old wood. To invigorate a plant, take out older branches all the way to the ground during the winter months. Only take out older canes (they are gnarled in appearance) and leave newer ones. In March, when new leaves begin to form, prune off the top growth of each branch cutting right above a growth bud (they are usually fat and fleshy and easy to recognize). New branches will form where you made the cuts and flowers will develop on them. If you need to drastically reduce the size of a large hydrangea, cut the branch lower (always right above a growth bud) but leave at least one third of the plant’s size unless you want to go a year without flowers.

Keep in mind that the various types of hydrangeas are pruned differently! (For pruning instructions for oakleaf, peegee, and smooth hydrangeas, consult the appropriate web pages on this site).

The Color Identity Crisis

Hydrangeas are unique plants in that the color of their blooms can change, fluctuate, and be deliberately manipulated by the grower. It is not uncommon to see a hydrangea sporting two different colors on the same bush! The cause of this is the amount of aluminum in the soil. An acid soil will produce blue flowers and alkaline soils exhibit pink flowers. Sometimes, if you are along the middle of the PH scale, you might get purple flowers. Oh, and if you are not already totally confused, white flowers cannot be changed at all!

I've heard of all kinds of recipes for changing the color of flowers - everything from scattering tea bags and coffee grounds around the plants to burying rusty nails under them. The best way to do this however, is to add aluminium sulfate to your soil if you want blue flowers and sulphur if you want pink flowers. Still, for plants growing in the ground, this is not that easy to do. Container plants are much easier to manipulate this way. My soil is on the acid side and I usually have blue flowers. I say to just let nature take its course and let your hydrangeas be any color they desire to be!

Hardiness

Generally, hydrangeas in this class are categorized as being hardy to zones 5/6. The shrubs themselves are hardy here in the southeast but sometimes flowers can be ruined by late frosts. Extended periods of warm temperatures during the winter followed by frigid temperatures can also be damaging. Since these weather patterns are typical here in the southeast, some years can be disappointments for hydrangea lovers. Click here for the USDA Plant Hardiness Zone Map.

The Florist Hydrangeas

I'm often asked if hydrangeas bought in supermarkets or those obtained from a florist can be planted outside in the garden. They can be but don't get your hopes too high. These plants have been raised and coddled in greenhouses. They are easily killed by cold temperatures if they have not acclimated themselves to the sudden change of environment. It can be done and I have seen beautiful plants growing in gardens in which the owner told me it came from a florist but for a tough, quality plant, I would purchase one from a nursery.

Cultivar List

Name	Flower Type	Close-Up View	Landscape View
Alpenglow (aka Glowing Embers)	Mophead
Amethyst	Mophead
Ami Pasquier	Mophead
Angel's Lace	Lacecap
Ayesha	Mophead
Big Daddy	Mophead
Blue Bird	Lacecap
Charm	Mophead
Dooley	Mophead
Endless Summer	Mophead
Fasan ('The Pheasant')	Lacecap
Geoffrey Chadbund	Lacecap
Grayswood	Lacecap
Lady in Red	Lacecap
Lanarth White	Lacecap
Lilacina	Lacecap
Mme. Emile Mouillere	Mophead
Mariesii Variegata	Lacecap
Merritt's Supreme	Mophead
Nikko Blue	Mophead
Pia	Mophead
Purple Tiers	Lacecap
Preziosa	Lacecap
Sister Therese	Mophead
Tokyo Delight	Lacecap
Veitchii	Lacecap
White Wave	Lacecap

 

Hydrangea Home

Macrophylla (Bigleaf)

Arborescens (Smooth)

Paniculata (PeeGee)

Quercifolia (Oakleaf)

Anomala (Climbing)