1 - Some reasons a nandina plant may do poorly.
Q. I have a small nandina plant that is at the southwest corner of my house next to a wall. In this location it does not get a whole lot of sun. It seems to produce healthy berries and new growth (not a lot). The leaves eventually turn yellow/brown on tips. I was wondering if you have any ideas on its growth/leaves. I have one in the backyard (east-facing) and it is very large and healthy.
A. Your nandina plant is illustrating the impact of microclimate (climate developed in a small geographic area as a result of structures, etc.) on the growth of plants in our landscapes. If I understand correctly, the nandina on the northeast side of a wall and the house is to the northeast of the plant, but not far away. The wall shades it from direct sunlight, but the house probably reflects light toward the plant. This should be enough light for growth. This location is probably quite warm on sunny winter afternoons. This results in rapid water loss from your plant, even in the winter. This orientation and warmth also results in more rapid drying of the soil. Since we often have winds blowing from the southwest, there is probably a wind or breeze that often swirls over the wall and around the nandina plant. This wind will also increase drying of the plant and soil. More frequent winter watering and mulch may help the plant retain moisture. However, the warmth of this location during the day and the cold at night may still create problems for your nandina plant. It may be better to move the nandina to a more favorable microclimate.
Another factor to consider is that the soil in the area near the wall and house may be more compacted (due to construction) and may not be permeable to water and air. This may be resolved by loosening the soil over a large area (larger than the initial rootball of the plant). The soil in this location may have excess calcium salts as a result of the house and wall foundation. This can result in salt burn. If there is stucco covering on the house or wall, this may have also increased the mineral salts in this location. Combined with swirling winds and drying, salt burn damage is very likely. Once again, efforts to maintain moisture in the soil may help.
A final factor to consider is variety. I have seen two nandina plants growing side by side on the south side of a building. One variety, the taller, more narrow-leafed variety did well. The dwarf variety with broader leaves exhibited leaf scorch every winter. The taller variety was more tolerant of the soil conditions and alternating day / night temperatures.
Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: firstname.lastname@example.org, office: 505-865-7340, ext. 113.
For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.
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