The Story of the Sick Spirea

© Ginger Hudson

Spirea, Bridal wreath, Spirea cantoniensis, S. japonica, S. nipponica, S. prunifolia, S. thunbergii

Spirea in full sun, thin alkaline soil

Once upon a time, before air conditioners, before water conservation, there were fabulous homestead gardens that boasted plants brought from home (the east or Midwest) or attempted to replicate English gardens. The replication effect came from garden books of the time, written by the English or by successful gardeners along the east coast of the U. S. As gardening expanded to become a show of aesthetics not just food production, the homes wanted a rich display of vegetative color and life. Homeowners in the central United States and Texas in particular wanted to have ‘fluffy’ lush gardens just like homes in the longer established states and towns of the time. My once-upon-a-time is ambiguous because this could be the late nineteenth century, the early turn of the century, or classic mid-century landscaping practices.

One of the mainstays of the old fashioned garden was Spirea, also known as bridal wreath with its arching, cascading white flowers. This member of the rose family is usually implemented as a shrub. Most varieties originate from Europe, China and Japan–regions with much more even keeled weather than that of Central to North Texas (note the latin names above for obvious clues). Although many gardening books produced in the U.S. claim Spirea are not particular about soil, I am going to disagree with that claim.

As evidence, I present the story of the sick Spirea which inhabit Central Texas. These subjects do grace the garden with wreaths of white flowers in the early to mid spring. Paired with a purple lorapetalum the combination is spectacular. However, as the year wears on temperatures climb, water supply weakens, and the alkaline affects of the soil eat into the plants causing their health to decline. The leaves of the Spirea yellow through their life with the classic sign of chlorosis, lack of access to iron in the soil. Yellow leaves with green veins. This can be corrected and symptoms treated in the short term with addition of ironite to the soil. Acidic compost blends or sulfur can be added to the beds and results will be seen in weeks to months after application. But the symptoms re-appear year after year.

Additionally, the heat stress exacerbates the yellowing effect as days on end of 90 to 100 plus degree temperatures stress the shrubs. With low rainfall totals in the Texas areas of question, the Spirea struggle to maintain their whole. They will let entire branches die off in the effort to save the heart of the plant. The summer gardener will rotate between watering and trimming of dead plant parts for three to four months of the year. This becomes a difficult chore in communities where water conservation efforts restrict landscape water usage to twice a week and eventually to once per week. Some communities on well-based water supplies may out-law landscape water usage altogether. In the end, the sickly Spirea are leaf-bare, and dried out. A wet winter may bring about new suckers and shoots for a season of spring blooms. But the headache of routine fertilization and watering is not worth the effort in a region where tougher plants should be selected for their adaptability.

In closing the case, gardeners have two choices in a soil and water challenged environment. First is to build up garden beds with rich, well-rounded composts. This can be accomplished with the addition of locally produced and blended garden soils, or with creation of the gardener’s own compost. Also, try to place the specimen in a zone of the landscape that naturally collects water you will face less of a heat stress issue. After a few seasons or couple years of build-up of a balanced soil, the Spirea will enjoy a healthy life in the garden. The second choice is to opt out of the Spirea selection altogether. If, however, you live in an area with higher rainfall, such as generally east of I-35 in Central Texas–Elgin, Bastrop, Columbus, and on into the Houston area, your soil may naturally be a little more acidic. Also, these areas tend to contain pine trees or the like that have produced a slightly lower ph soil base. In these regions the gardener will have more success with the Spirea family.