Spirea douglasii is a species of flowering plant in the rose family. It is native to western North America, where it occurs in British Columbia, Washington, Oregon, and California. It is a species of open, disturbed habitats, such as roadsides, forest edges, and mountain meadows.
Related plant:
Spirea Japonica Anthony Waterer
Related plant:
Spirea Japonica Little Princess
About soil condition, Spirea douglasii grows in moist to wet soil that is rich in organic matter. It does best in full sun, but it can tolerant some shade. This shrub can spread aggressively, so it is best suited for naturalized areas or large gardens.
Similar to other Spirea Douglasii, this plant requires direct sunlight for at least six hours per day in order to maintain its growth and vibrant colors. If you live in an area with limited sunlight, you may find that your plant grows more slowly or doesn't produce as many flowers. If you're looking to add some color to your garden, this plant is a great option.
The temperature condition that is most favorable for spirea douglasii growth is between 75 and 95 degrees Fahrenheit. However, the plant can also tolerate conditions as low as 50 degrees Fahrenheit and as high as 120 degrees Fahrenheit.
Ideal humidity condition for this plant is 50%. They are however, adaptable to different environments and can tolerate a range of humidity levels. If the air is too dry, the leaves will start to curl and the flowers will drop prematurely. If the air is too wet, the leaves will start to yellow and the plant will be more susceptible to fungal diseases.
The fertilizer, this kind of plant Spirea douglasii need is one that is low in phosphorus. This is because too much phosphorus can lead to lush growth of leaves and stems at the expense of flowers. If you decide to use a fertilizer that contains phosphorus, apply it to the soil around the base of the plant, taking care not to get any on the leaves. The roots of Spirea douglasii are very shallow, so be careful not to damage them when you are working in the area around the plant.
Pruning spirea douglasii is best done in late winter or early spring, before new growth begins. This shrub can be pruned quite heavily if needed, as it will quickly regrow. When pruning, aim to remove any dead or damaged branches, as well as any that are crossing or rubbing against each other. You can also thin out the shrub to promote air circulation and help prevent disease.
Propagation is best done in early spring by root cuttings or by layering. Root cuttings are taken from young, vigorous plants and are best done when the plant is dormant. Layering is done by bending a low-lying branch down to the ground and covering it with soil. The branch will root where it touches the ground and can be severed from the parent plant once it is well rooted.
Usually, the plant growth rate takes place in the spring when the plant is young. The plant can grow quite rapidly,up to 2 feet per year. Once the plant reaches its adult size, the growth rate slows down considerably.
Common problems for this kind of plant are aphids and rusts. Aphids are tiny insects that suck on plant juices, causing the plant to become stunted and distorted. Rusts are fungal diseases that cause orange or brown spots on the leaves. Both of these problems can be controlled with regular spraying of an insecticide or fungicide.
Source:
Western Spirea - Spiraea douglassi - PNW Plants
Spiraea douglasii - InsideEWU
Spiraea douglasii Willamette Valley Prairies
