How to Grow and Care for 'Gold Mound' Spirea

'Gold Mound' spirea is a deciduous shrub prized for its bright golden ovate leaves in spring, which turn a brilliant yellow in autumn. It has flat-topped clusters of tiny, bright pink flowers in late spring to mid-summer, which attract butterflies. This plant has a mound-like growth habit and is most prized for its spring leaves. Although in fall, usually by October, its leaves are yellow-tinged with red.

Gold Mound spirea grows best in full sun, acidic to neutral well-draining soil, and moderate temperatures, although it can tolerate temperatures down to -30 F. It is a cultivar, a hybrid cross between S. japonica 'Alpina' and S. japonica 'Goldflame,' which matures at two to three feet tall and three to four feet wide. Gold Mound spirea has a fast growth rate, can grow 2 feet in its first season, and is suitable for container growing.

Gold Mound Spirea Care

Here are the main care requirements for growing Gold Mound spirea:

• Grows best in acidic to neutral, well-drained, moist soil.
• Plant it in a full sun spot, although it can tolerate partial sun.
• Space Gold Mound spirea at least three feet apart.
• Experiences growth in temperatures between 40 to 95 degrees Fahrenheit.
• Enters dormancy in winter; losing it leaves.
• May rebloom after pruning faded flowers.
• Doesn't usually interest deer.

Light

Gold Mound spirea prefers full sun but will tolerate light shade when possible. Planting it in a sunny location helps to ensure the best color.

Soil

This plant will grow best in well-drained soil, although it tolerates clay soils better than other shrubs. Amend the soil with compost as needed. Gold Mound spirea prefers a pH range of 5.5 to 7.5. Mulch for winter protection if you wish to grow it in USDA cold hardiness zones 4 or 5 to be on the safe side. The plant is hardy to -30 degrees Fahrenheit.

Water

Thoroughly water this shrub every week during the summer (unless it rains steadily for several days, you can skip a week). Water until the roots are saturated, but don't overwater; Gold Mound spirea doesn't like overly wet conditions.

Temperature and Humidity

Gold Mound spirea grows in USDA zones 4-8, which can tolerate temperatures as low as -30 F. However, it will not fare well in these subzero temperatures for sustained periods. It experiences its best growth in temperatures from 40 to 95 F. It doesn't have any particular humidity needs.

Fertilizer

These hardy plants should be fertilized in late winter or early spring before new growth. A general-purpose garden fertilizer is fine. For the amount to use, follow the product label instructions. Be sure to water thoroughly after applying fertilizer.

Types of Golden Japanese Spirea

Because of the striking color of their leaves, Gold Mound spirea bushes are more suitable for use as specimen plants or foundation shrubs than the cultivar Neon Flash, the latter bearing foliage that's nothing out of the ordinary. Gold Mound spirea grows like the similarly-shaped variety Goldflame spirea.

Other cultivars of Spiraea japonica that have golden leaves and pink flowers and that are hardy to zone 4 are the following:

• 'Magic Carpet' is a compact cultivar, ideal for small yards. It grows to just one to two feet tall, with a width of two to three feet.
• 'Golden Elf' is even smaller than 'Magic Carpet'. This dwarf stands at just a little over six inches tall, one to two feet wide.
• 'Lemon Princess' reaches one and a half to two feet tall and has a width of two to three feet.
• 'Double Play Gold' also reaches one and a half to two feet tall and has a width of two to three feet.
• 'Limemound' grows two to three feet tall and three to four feet wide.
• 'Golden Princess' also matures at two to three feet tall and three to four feet wide.

Pruning

Deadhead Gold Mound spirea after they're done blooming. This will foster some reblooming as the growing season progresses. The easiest way to deadhead, in this case, is by shearing. In addition to removing spent flowers, shearing will help you keep the shrub compact and generate new foliage (the newest foliage being the most colorful parts of this plant).

Pruning full branches is usually necessary only to remove suckers (if so desired) or to rejuvenate a mature plant. You can also prune branches to keep the plant extra-compact if gardening in a small space. Not all plants respond well to the drastic operation of rejuvenation pruning, but spirea does. If you decide to prune, you can do so in late winter to early spring without fear of losing your spring flowers because this plant blooms on new wood.

Propagating Gold Mound Spirea

The easiest way to propagate the shrub is by softwood cuttings. It's best planted in the spring or fall. 

1. Cut a branch tip 4 inches in length in late spring using a sharp knife or pruner. Remove leaves from the lower third and dip the stem in rooting hormone.
2. Fill a 4-inch pot with potting mix and water until evenly moist but not soggy. Using a pencil or a stick, poke a hole in the soil deep enough to fit the leafless portion of the cutting. Insert the cutting into the soil and press it down.
3. Place the pot in a bright location with indirect light, away from the hot sun. Keep the plant moist at all times. When roots have begun forming (a sign of new leaf growth), you can transplant the spirea in garden soil or a larger pot for container growing.

How to Grow Gold Mound Spirea From Seed

Although spirea tends to reseed itself, the seeds won't produce the same results as the parent plant because Gold Mound is a hybrid. Therefore, the recommended propagation is from cuttings.

Potting and Repotting Gold Mound Spirea

Because of its compact size, this spirea is suitable for container growing. Choose a container at least one inch wider than the plant's root system's or current pot's diameter, and ensure it has large drain holes. Terra cotta pots are ideal because they let excess moisture evaporate and are heavy enough to keep the plant upright in the wind.

Like all container plants, it must be watered and fertilized more frequently, about once a month, during the growing season. Use a diluted all-purpose fertilizer, half the strength of what is indicated on the label.

Overwintering

Gold Mound spirea is hardy to USDA zone 4 and does not need winter protection when grown in the ground. On the other hand, the roots are not sufficiently protected from winter chills when grown in a container. You do not need to bring the plant inside; provide additional insulation around the container. You can either build an insulating silo, wrap the sides of the container with bubble wrap, burlap, or an extra layer of plastic wrap.

Common Pests and Plant Diseases

Spirea can be prone to leaf spot and powdery mildew. These fungal conditions thrive in hot, humid weather. This condition can be reduced by increasing air circulation around this plant.

These plants often host spirea aphids, which can be treated with insecticidal soap, repeating as needed.

How to Get Gold Mound Spirea to Bloom

If your spirea isn't blooming, it could be that it is not getting enough sunlight; the shrub needs full sun to bloom. Another possibility is over-fertilization with nitrogen, which produces foliage but no flowers. Cut back on the fertilizer, or use a fertilizer high in phosphorus when you fertilize it before the next growing season.

Bloom Months

Gold mound spirea typically blooms between June through August.

How Long Does Gold Mount Spirea Bloom?

Spirea flowers usually last about five weeks, reblooming every year. Pruning after summer bloom might encourage a second round of blooms before the end of the growing season.

What Do Gold Mount Spirea Flowers Look and Smell Like?

It has flat-topped clusters of tiny, bright pink flowers in late spring to mid-summer. The flowers have a mild, hardly perceptible fragrance.

How to Encourage More Blooms

Pruning the floral branches after blooms fade may encourage a second flush of flowers.

Common Problems With Gold Mound Spirea

Because Japanese spirea spreads rapidly by dispersing many tiny seeds and outcompetes native species in natural habitats, such as forests and meadows, it is considered an invasive plant in several US states.

Yellowing Foliage Caused by Dog Urine

Insect infestations can often cause yellowing. However, if you do not notice any insect activity but have plants along a popular dog-walking route, the yellowing may be caused by foliage burn from dog urine. Dog urine burn will first affect the lower foliage, discoloring it.

To prevent dog urine burn, spray the vulnerable foliage with an anti-transpirant to protect the plant. Also, spray a dog repellent spray near the base of the plants to keep dogs away. To encourage new, healthy growth, prune away dead or damaged sections.