As a landscape contractor, it is often difficult working within the parameters of a client’s preference for a certain foliage look and trying to create a hardscape that is attractive and enduring. Most people are not aware of the activity underground that many plants affect. Plant selection and planter size can make or (literally break) the hardscape of a beautiful home simply because the growth parameters of the softscape were not considered.
Case in point, the gorgeous tropical giant Strelitzia Nicholai, or giant bird of paradise, is a notorious felon in terms of hardscape and concrete destruction. The giant bird is perfect for creating a tropical look around the pool. It never drops any leaves or debris into the water and being from South Africa it grows well in our temperate climate. However, it is the closest thing to a hydraulic jack (except for the Phoenix Canarienses) that you will ever come across.
The roots of the giant bird are the same as most palm trees. Each individual root does not change in diameter, only in length. The tip of each root produces new cells and thus can drive through or break just about anything. I have seen it push easily through 50-mil. pond liners, sealing the holes with its root as it continues on into the surrounding soils. I have even seen it blow through a half-inch-thick hard green plastic valve box.
But this is just the beginning of what this plant can do above and below the ground. As this bird grows higher, it constantly sprouts new pulps from the base and creates a larger and larger root ball base. A good tree man will thin out some of the pups but the most desirable look for the Nicholai is a multilevel set of trunks that create an upper story canopy, a middle-story canopy and a lower-story canopy that hides the inherent ugliness of the root base.
As the individual trunks get taller, eventually they lose their vitality and must be removed before they fall or snap from the weight of the water heavy head. Cutting them at the base allows for more light to reach the lower-story foliage and the cycle starts anew. The only problem here is that the base of the plant, especially that of an older specimen, will continue to expand above and below the ground.
Planted too close to a fence, this plant can and will push over a block wall. Placed in a small planter space, eventually the concrete will mound as the roots spread under it and crack, ruining thousands of dollars of expensive hardscape.
Like Clint Eastwood said, “A man’s got to know his limitations.” And so it is in the plant world. When designing planting spaces surrounded by concrete, large specimen plants are usually a mistake. One trick I like to employ when caught in this quandary for upper-story shade in a limited planting space, is to create a large planter space or mound and then place large rocks or boulders around the outside of the large specimen tree or plant.
As the tree grows larger, its roots go under the rocks, around it and move them, not the hardscape. No one notices when a rock moves slightly and this helps create concrete saving space between the large specimen tree and the concrete. Watering with drip is another trick to saving your concrete since copious amounts of water exacerbate the situation as well. Excess water in the soils promotes faster root growth and wet soils that refuse to perk (clay) will expand and contract depending on their moisture content.
The giant bird has large purple and white flowers. From these flowers seed is generated and pollinated by a host of insects. The flowers are extremely vascular and will drop a huge amount of sugary sap. This can attract ants like crazy, which bring with them a whole host of problems from black sooty mold to aphids and white fly. By pruning these flowers off the heads and peeling the old boots or leaf bases on the trunks with a box cutter, your bird will look good for years to come.