How To Grow And Care For 'Ruby Slippers' Hydrangea

Hydrangeas are adored for brightening a shadier garden with beautiful blooms in summer. While there are many types of hydrangeas to choose from, the oakleaf hydrangea is a popular pick for good reason. They grow wild in the woods of the Southeast, sporting cone-shaped white blooms in summer that turn papery brown in fall, when the leaves turn rich shades of red, orange, and maroon. The oakleaf can have quite a reach, growing out to 8 feet wide, so it doesn't fit in every garden. For a smaller oakleaf hydrangea with the added excitement of blooms that transform from white to deep pink, consider 'Ruby Slippers,' a cross of two popular oakleaf hydrangeas that was developed by the U.S. National Arboretum.

With a mature size of about 3 to 4 feet tall, this plant is a good choice for hedges, borders, cutting gardens, or even container gardens. 'Ruby Slippers' boasts a multitude of stocky flowers that show up as white or pale pink and then mature to a striking deep rose. The large, oak-shaped, deep green leaves put on a show in the fall, turning pink, scarlet, and burgundy. If one healthy hydrangea plant produces beautiful blooms and foliage, imagine what a grouping would do for the aesthetic of your property. Bump up the wow factor and plant several 'Ruby Slippers' for an incredible display all year round. Just make sure to keep an eye on young children and pets, as hydrangeas are mildly toxic.

'Ruby Slippers' Care

Like most oakleaf hydrangeas, 'Ruby Slippers' requires good drainage and fertile soil. Water regularly while the plant is getting established and use mulch to keep the shallow roots cool. Oakleaf hydrangeas bloom on last year's growth, so prune them minimally right after they bloom.

Light

Oakleaf hydrangeas should be sited in a location with more sun in cooler climates and less sun in hotter areas. If you live in the Upper South, plant 'Ruby Slippers' in full or partial sun for the best show of flowers. Your shrub should be exposed to at least two to six hours of direct sun a day. In warmer areas (Zones 7-9), 'Ruby Slippers' will perform best with morning sun and afternoon shade, or with filtered shade much of the day. Some sunlight is necessary for a good bloom. The flowers develop more intense color in full sun.

Soil

As a woodland plant, oakleaf hydrangeas prefer well-drained soil that is rich in organic matter. Oakleaf hydrangeas grow best in mildly acidic soil, but will also do fine in neutral soil. Alkaline soils must be amended with sulfur, iron sulfate, or aluminum sulfate. Clay or sandy soils should be amended with compost or other organic matter to improve drainage and moisture retention. A layer of mulch, shredded leaves, or pine straw can help preserve moisture as well.

Water

Oakleaf hydrangeas stand apart from other types when it comes to drought tolerance, but they still do best in moderately moist soil. Water 'Ruby Slippers' regularly and deeply during its first growing season to help it get established in the garden. After that, you can limit watering to when the top 2 inches of soil is dry. If you are growing 'Ruby Slippers' in a container, water whenever the top inch of soil is dry.

Temperature And Humidity

In the South, 'Ruby Slippers' can be grown anywhere except in tropical Zone 10. It is not as reliably winter hardy in the northern limits of its range in the Midwest and Northeast. This plant stands up well to hot conditions, both dry and humid, as long as it gets water.

Fertilizer

Organic matter provides all the fertilizer 'Ruby Slippers' needs in most cases. You can add a thin layer of compost each year, or pile a few inches of autumn leaves around your shrub. There is an exception: If you planted 'Ruby Slippers' in alkaline soil, use a water-soluble fertilizer like Miracid to feed your shrub and make or keep the soil acidic.

Pruning

'Ruby Slippers' is a compact hydrangea that requires very little pruning. Remove any winter-damaged stems in early spring, then reserve further pruning for just after the shrub flowers. Most years, pruning is not required at all or is limited to removing a crossing or stray branch. If you don't want to retain the dry flowers in winter, remove them by cutting stems just below the flowers.

Propagating 'Ruby Slippers' Hydrangea

'Ruby Slippers' can be propagated through softwood cuttings—the soft, flexible new growth on your shrub—in spring or early summer. These have a better chance of rooting than hardwood. Follow these steps to propagate your plant:

1. Preferably on a cool morning, cut a 5- to 6-inch length of soft green stem just below a leaf node. Choose a stem that appears healthy and is not flowering.
2. Remove leaves from the bottom half. To keep the large leaves from wilting, cut off half of each remaining leaf with a sharp pair of pruners.
3. Dip the bottom of the cutting into rooting hormone. Stick the cutting about 2 inches deep into a 4-inch pot filled with moist, lightweight potting mix.
4. Water well and place outdoors in a shady spot if weather is mild. You can also bring your cuttings indoors and set in bright, indirect light, placing a clear plastic bag over each pot to preserve moisture.
5. Monitor your cutting for the next four weeks, watering to keep moist. You can remove the plastic once roots develop and the plant starts to grow.
6. With indoor cuttings, begin to gradually harden off the cuttings by placing them outdoors for an increasing amount of time. Transplant in a couple of weeks or wait until the plant is more mature, transferring it to a larger pot in the meantime.

Large hydrangea shrubs can also be propagated by layering. Here's how you do it:

1. In summer, dig a thin trench below a low-hanging branch that is able to bend to the ground. Remove any leaves except for the last 6-12 inches of the branch's tip. Use a knife to gently scrape the bark off of the bottom of the stem where it will contact the ground.
2. Bury the branch in the trench, leaving that last 6 to 12 inches of the branch's tip exposed. You can place a brick or rock over the buried branch to hold it down.
3. Leave the branch in place through the following year until the shrub goes dormant in late fall or winter. Then clip the branch from the mother plant just below where it has rooted, and transplant.
   

Potting And Repotting 'Ruby Slippers'

'Ruby Slippers' is a great hydrangea for growing in containers due to its small size. First, select a pot that is at least 2 inches wider than the nursery pot. A container that is 16-24 inches wide can last for several years. The pot should have drainage holes and be frost-proof if you have cold winters. Fill the bottom of the pot with a high-quality potting soil, place the shrub so that it sits at the same level it did in its nursery pot, and then fill in with soil around it. Water the soil well and add a thin layer of mulch over top. Many potting soils contain fertilizer, in which case you won't need to add fertilizer until the next growing season. Each year in early spring, add a fertilizer that is labeled for roses or flowering shrubs.

You'll know when your hydrangea outgrows its pot if roots begin to emerge from the bottom and you have trouble keeping the soil moist. You can repot it in a larger container or transplant it in the garden. When repotting, use fresh soil rather than the old potting soil, which leaches nutrients over time.

Overwintering

'Ruby Slippers' is hardy throughout the South, but applying a thick layer of mulch in winter will help protect the roots in the upper part of its range. Add 2 more inches of mulch on top of the existing mulch after the ground freezes. The excess mulch can be removed in spring.

If you are growing 'Ruby Slippers' in a pot, the roots have considerably less protection from freezing temperatures. You must live in a climate that is two zones warmer—that is, in Zone 7—in order for 'Ruby Slippers' to reliably survive the winter. If you live in the Upper South, move your container to an unheated garage or similar space once the plant goes dormant. Water occasionally during the winter, especially during warmer spells, to keep the plant alive and healthy. Then move it back outdoors when temperatures begin to warm up in spring.

Common Pests & Plant Diseases

Spider mites and aphids may nibble on hydrangea foliage. A strong stream of water from a hose will control infestations much of the time (you may need to do this several days in a row). With a more serious infestation, use insecticidal soap. Deer enjoy nibbling on the leaves and flowers. Use a repellent spray to discourage them.

Oakleaf hydrangeas rarely have serious problems. If you see signs of leaf blight (small spots with yellow halos that spread) or powdery mildew (dusty white coating on leaves), make sure you are not wetting the foliage when watering. You can spray the leaves with fungicide if the plant's health is affected.

How To Get 'Ruby Slippers' To Bloom

'Ruby Slippers' should begin blooming in May or June. If you don't see any flower buds, improperly timed or aggressive pruning is the most likely culprit. This shrub blooms on old wood, which means it sets its flower buds in late summer for next year's bloom. Limit your pruning to right after the shrub flowers, or don't prune at all. Sometimes cutting spent flowers off just below the inflorescence can encourage more blooms. If your shrub is planted in deep shade, you may need to increase light exposure to see any flowers.