Q. I have a bottle brush shrub that is open and getting yellow. What to do? A. The Australian bottle brush plant is sold as a shrub but can reach heights of 25 feet so it can also qualify as a small tree as well. Bottlebrush varies from dwarf types to trees and flower color from red to white to pink.  Flowers of the red bottlebrush. Later the flowers produce this which are seed capsules. Dwarf Types Just don’t use dwarf types like ‘Little John’ if you want a larger tree sized plant. In tree form it can be used on single story homes for shade. To be on the safe side plant it away from hot walls. There is a weeping form and a non-weeping form as well as dwarf varieties. Also flower color can range from yellow to red and shades of red to pink and white. One of the dwarf types, don;t know which one, with freezing damage. Yellowing Leaves             It oftentimes has a problem. Yellowing of the leaves oftentimes occurs when the soil is low in nutrients as well as its organic matter content. Fix yellowing by applying a landscape fertilizer every year in the spring and combine it with an annual application of chelated iron. Enriching the soil with organic matter is done when you used small rocks by raking them back and applying a thin layer of compost to the soil, wetting it, and raking the rocks back. Large rocks may not need raking. The compost and fertilizer will just wash through it to the soil. One of the iron chelates, EDDHA. I prefer this type of iron chelate because it is stable regardless of the soil pH. Other iron chelates like EDTA and DTPA iron chelates become ineffective at soil pH above about 7.6. Apply it early in the growing season when you make a fertilizer application. Increase Density of Canopy             To improve the density of its canopy, make sure it gets enough water. The plant grows best if treated as a “mesic” plant rather than a desert or xeric plant. It grows well when surrounded by lawn. Water should wet the soil about three or four feet in diameter to a depth of about 18 to 24 inches deep each time. Water it as you would any mesic plant such as ash, bottle tree, African sumac, and others. As this plant approaches ten feet tall then wet the soil about five to six feet in diameter. Another possibility might be low soil organic content. So rake the rock away and put a thin layer of compost on top of the soil, water it in and replace the rock. Pruning to Tree             To get a small tree out of this, remove the lower limbs when it is 3 or 4 four feet tall so that the canopy occupies about 2/3 and the trunk is about 1/3 of its height. Plant it at least five feet away from hot walls or it will fry. Also in the desert remove lower limbs slowly as the lower limbs touch the ground. Otherwise the trunk may get sunscald.