Posted by Brent Wilson on 9/28/2016 to Fertilizing & Watering Tips
Bottlebrush, scientifically known as Callisetmon, are exceptionally easy to grow when planted right and in the right spot. Their unique, brightly colored, bottlebrush-like flowers add exciting visual interest to the garden.
Bottlebrush have multiple uses in the landscape. When grown as a shrub they are useful as specimens, in groupings or as formal or informal hedges and screens. Taller growing varieties can be "limbed up' to form an attractive small tree that is ideal for use as an an eyecatching specimen or to mark corners or entryways. A great addition to tropical and butterfly gardens or Xeriscape (low water needs) gardens.
Here's a breakdown of what you need to know for how to plant and care for Bottlebrush...
Bottlebrush adapt to wide range of soils. Though tolerant of dry periods when established, they prefer a moist but well-drained soil of average fertility. As with so many other types of ornamental plants, constantly soggy or wet soil can be problematic.
How To Test Soil Drainage
If you are uncertain about soil drainage in the area you intend to plant your Bottlebrush, it's well worth taking the time to test the drainage before planting. To test soil drainage, dig a hole 12" wide by 12" deep in the planting area. Fill the hole with water and let it drain. Then, after it drains, fill it with water again, but this time clock how long it takes to drain. In well-drained soil the water level will go down at a rate of about 1 inch an hour. A faster rate, such as in loose, sandy soil, may signal potentially dry site conditions. A slower rate indicates poor draining soil and is a caution you need to improve drainage, plant in a raised mound or bed, or look for plants that are more tolerant of wet or boggy conditions.
Soil pH is a measurement of the alkalinity or acidity of soil, which is measured on a scale of 1-14, with 7 as the neutral mark. Any measurement below 7 indicates acid soil conditions, and anything above 7 indicates alkaline.
Bottlebrush grow best in a slightly acid to slightly alkaline soil with a pH between 6.0 to 8.0 on the pH scale. Most average garden soils fall between a pH range of 6.0 to 7.0.
If you're unsure about the pH of your soil, or whether or not it's suitable for growing Bottlebrush, it's a good idea to test the soil pH in the planting area. You can quickly test soil pH with an inexpensive soil pH testing kit or probe. To raise the pH (make more alkaline) you can add pelletized limestone to the soil. To lower the pH (make more acid) you can apply Soil Sulfur, Aluminum Sulfate, or Chelated Iron. Adding organic compost to the soil or using compost as mulch can also help to increase acidity and maintain acid soil conditions.
Bottlebrush will grow in full sun or part shade. For best flowering provide at least 5 hours of direct sunlight or all-day lightly filtered sun. Morning shade with afternoon sun or morning sun with afternoon shade is okay.
Planting Bottlebrush In The Ground
Scroll down for container planting instructions
Start by digging your planting hole at least two to three times as wide and no deeper than the rootball of your Bottlebrush plant. The wider the hole the better. Place native soil removed from planting hole around the perimeter of the hole, in a wheel barrow, or on a tarp.
Depending on type, fertility and porosity of the native soil in the planting area it might be beneficial to amend the native soil. When planting in dense clay or other compacted soils it is beneficial to thoroughly mix in some bagged top soil and/or a good planting mix at a 50/50 ratio with the soil removed from the planting hole. When planting in very sandy, quick-draining soil you might want to consider mixing in some top soil, peat moss and/or compost to help retain moisture. When planting in fertile, loamy, well-drained soil there is no need for adding a soil amendment.
Be very careful when removing your Bottlebrush plant from the nursery pot it was growing in. Gently try to lift the plant from the pot. If the rootball is stuck in the pot, to avoid damaging the plant, cut the container away. After having removed the plant from the container, use your fingers or a claw tool to gently loosen some feeder roots around the surface of the root ball.
If you are planting in well-drained soil set your Bottlebrush in the planting hole so that the top edge of the rootball is at or slightly above ground level. If necessary, add some backfill soil mixture to the bottom of the hole to achieve proper planting height.
NOTE: If the soil is poorly drained (constantly soggy or wet) improve drainage in the planting area or select a different plant species more tolerant of wet soils.
After setting your Bottlebrush in the planting hole, use one hand to hold the plant straight and your other hand to begin back-filling your soil mixture around the root ball, tamping as you go to remove air pockets. When you have filled the hole to the halfway point you can soak the soil. Then continue back-filling to the top edge of the root ball. To avoid suffocating your plant, avoid placing any soil on top of the root ball.
Step 6 (Optional)
When planting Bottlebrush in a location that is far from a water source, you can use remaining soil mixture to build a water retaining berm (catch basin/doughnut) around the outside perimeter of the planting hole. Only build this berm if the soil is very well-drained. This basin will help to collect water from rainfall and irrigation often reducing the need for hand-watering. The berm can be removed after a year or so when the plant has established itself.
Next, deeply water the planting area, including the root ball, to a depth equal to the height of the root ball. For an extra boost, and to stimulate early root formation and stronger root development, you can also water you newly planted Bottlebrush with a solution of Root Stimulator, which reduces transplant shock and promotes greener, more vigorous plants.
Spread a 1- to 2-inch layer of shredded or chipped wood mulch or a 3-4-inch layer of pine straw around the planting area to conserve moisture and to suppress weed growth. As the mulch decomposes it will add vital nutrients to the soil that your plants will appreciate. Avoid using freshly chipped or shredded wood for mulch until it has cured in a pile for at least 6 months, a year is better. Avoid placing or piling mulch directly against the base of your plant as this could cause the bark to rot.
Container Planting Instructions
Bottlebrush plants are ideal for use in container gardens. When growing in pots they appreciate a moist but well-drained soil. Constantly soggy soil can and often will cause root rot or other harmful plant diseases. Therefore, make sure the planting pot has a drainage hole(s) and use a quality potting soil or potting mix, or a 50/50 combination thereof for planting. You can also add some perlite or pumis at a 10 to 20% ratio to the soil mix to help with drainage.
Choose a container that is large enough to allow for 2 to 3 years of growth before shifting up to a larger size container. This might mean your planting pot would be 8 inches or more in width than the root ball of your plant. If you'll be growing other plants in the same container up the size of the container.
Container color will matter as well. Not only will you want to pick a color of container that goes well with the flower, foliage and flower colors of your Bottlebrush, you'll also want to pick a container that matches the style of your home or other structures and plants in the surrounding environment.
Many nursery & garden centers offer a wide variety of containers to choose from. Before heading out to buy a container take pictures of your home and the surrounding environment. Doing so will help you to choose just the right color and style.
Before filling your container with the soil mix, we recommend lining the bottom with shade cloth or a porous landscape fabric. This will keep the drain holes from becoming stopped up with soil. If you use stones or other materials in the bottom of the container lay the fabric on top of it.
Be very careful when removing your Bottlebrush plant from the nursery pot it was growing in. Gently try to lift the plant from the pot. If it is stuck in the pot, to avoid damaging the plant, cut the container away. After having removed the plant from the container, use your fingers or a claw tool to gently loosen some feeder roots around the surface of the root ball.
Pour a small amount of your soil mixture in the bottom of the container. Set your Bottlebrush plant in the container and make necessary adjustments by adding or removing some soil so that the top edge of the root ball will sit 1" or so below the rim of the container.
Backfill with your potting soil around root ball, tamping as you go, until the level of potting soil is even with the top edge of root ball.
Water thoroughly until water starts to drain from the holes in the bottom of the container. Add more potting mix if settling occurs during watering.
Step 6 (Optional)
Apply a 1/2" layer of pine bark or wood chips to soil surface to help conserve moisture and prevent weed growth.
Caring For Bottlebrush Plants
How To Fertilize Bottlebrush Plants
Bottlebrush will benefit from fertilization. To maintain deep green foliage and support growth and overall health of the plant, feed your Bottlebrush in early spring, and again in late spring or early summer, with a slow-release shrub & tree food, preferably one containing sulfur and/or iron. Alternatively, you can feed with a natural organic plant food. To avoid stimulating new growth that could be damaged by an early frost, cease fertilization two months prior to the first frost date in your area.
Feed Bottlebrush growing in containers as directed on product label with a timed-release or water soluble fertilizer listed for use in containers.
Soil pH - Bottlebrush plants grow best in a slightly acid to slightly alkaline soil ranging from 6.0 to 8.0 on the pH scale. Most average garden soils fall between a pH range of 6.0 to 7.0.
Learn More: What is Soil pH and How To Test & Adjust It?
How To Water Bottlebrush Plants
Bottlebrush are moderately tolerant when established. That said, in the absence of rainfall, young plants will require some moisture during the first year while establishing a root system. As with so many other plants, constantly soggy or wet soil can cause harmful root diseases and even death. So be careful not to over-water them!
Immediately after planting your Bottlebrush deep soak the soil in the planting area, including the rootball, to a depth equal to the height of the root ball. An application of Root Stimulator will provide an extra boost to stimulate early root formation and stronger root development. Root Stimulator reduces transplant shock and promotes greener, more vigorous plants.
During First Growing Season
In average garden soil you should not have to water your newly planted Bottlebrush every day. More often than not, this causes soggy soil conditions that can lead to root rot and other harmful plant diseases. In the absence of sufficient rainfall, water plants only as needed to keep the rootball and surrounding soil damp to moist.
Keep in mind that deep soaking less frequently, allowing the soil to dry out somewhat before watering again, is much better than splashing just a little water on the plants every day. Shrubs planted during the winter dormant season, when plants are not actively growing and evaporation is much slower, will require much less water. So, be extra careful not to overwater during winter!
When established, Bottlebrush plants are moderately drought and will only require supplemental irrigation during periods of drought. If you see new leaves wilting this could be a sign your plants could use a good deep soaking.
Note: When watering with an automated irrigation system it's best to set your timer to water during the early morning hours and not in the late evening or at night, which can lead to the onset of fungus and other foliar diseases. Test the soil moisture often during the first few weeks after planting and adjust irrigation time if necessary to maintain a moist but not wet soil.
How To Prune a Bottlebrush Plant
Bottlebrush do not require pruning, however respond well to it. They can be grown as a shrub or 'limbed up' to form a very attractive tree.
When to Prune
More extensive pruning to reduce size should be performed in late winter or immediately after the early spring flower cycle. Light pruning for shaping can be performed almost any time of year. Cease pruning 2 months prior to the average first frost date in your area.
For shaping, use a sharp pair of bypass hand pruners to cut stray branches back to a point just above the main form of the plant.
Remove dead or diseased wood by pruning the entire branch back to a point of healthy, disease-free growth.
We recommend growing Bottlebrush as a natural, informal hedge, which does not require the use of hedge trimmers to shear the plant. Shearing with hedge trimmers will cut large leaves in half, leaving an unsightly appearance.
Bottlebrush can be "limbed up" to form a very attractive, evergreen, single- or multi-trunk tree. It is best to allow your Bottlebrush to grow to at least 4 to 5 feet in height before tree forming.
When pruning for tree-form, the goal is to form a dense canopy atop one to several exposed trunks. To tree form your Bottlebrush, start at the base of the plant removing suckers growing from the base and lower branches, working your way up to a desired height. Make your cuts a quarter inch beyond the intersecting branch or trunk. Before removing a branch, make sure that its removal will not spoil the shape of the canopy. After removing a branch, it's a good idea to step back to view your work before moving on to the next branch.
In future years you can clip off any suckers that might grow from the base of your Bottlebrush tree any time of year. As your tree grows taller, continue to remove lateral branches from the trunk stems until your tree has the desired size and proportion of canopy to trunk.
Plant Long & Prosper!
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