Cheap, lightweight and easy to manipulate, burlap has become a popular way to protect transported B&B trees from the nursery to their planting site. To add justification for its use it’s also touted as biodegradable. “No need to remove it!” or “Leave it in place to protect the root ball.” and other such phrases are often tossed at the unknowing homeowner but are they laudable? Let’s investigate.
Hessian soldiers ca. American Revolutionary War – what do they have to do with burlap?
Burlap is the North American name used to refer to a fabric known as hessian in other parts of the world (except in Jamaica where it’s called crocus.) “Hessian” is attributed to the historic use of the fabric as part of the uniform of soldiers from the former Landgraviate of Hesse and its successors, including the current German state of Hesse. Soldiers from these areas were called “Hessians”. If you recall your American Revolutionary War history, the name Hessian might ring a bell.
While the word burlap might bring to mind the image of a coarse brownish material, Hessian fabric is available in different types of construction, form, size and color. Even though the two names refer to the same fabric, we’ll stick with “burlap” for our discussion.
Burlap is produced from two Corchorus species in the Malvaceae family. The main fiber source is C. olitorius but the fiber from C. capsilarius is considered superior to it having a finer texture. Both plants are called jute, which also applies to the fiber.
Jute grows best in a warm, wet climate. A long monsoon season followed with consistent temperatures over 75ºF/ 25°C and relative humidity of 70%–90% are ideal. Jute requires 65″-80″/160–200 cm of rainfall yearly plus extra during the sowing period. The plants prefer river basins, alluvial or loamy soils with a pH range between 4.8 and 5.8. Periodic flooding or marshy conditions are well tolerated. ~85% of the world’s jute is grown in the Ganges Delta.
When ready to harvest, the jute is cut off at the soil surface and gathered into bundles for transport and processing. To extract the fiber, the jute bundles are retted. There are a variety of retting processes: mechanical (hammering), chemical (boiling & applying chemicals), steam/vapor/dew retting, and water or microbial retting. Water or microbial are the oldest forms and most often used.
When the jute is well retted, the bundles are hit with a long wooden hammer to loosen the fibers from the core. After loosening, the fibers are washed with water and squeezed dry. The extracted fibers are further washed with water then hung up to dry. When dry they’re tied into bundles to be sold at market.
So what does all of this have to do with B&B trees?
Burlap, even a tightly woven burlap, “breathes.” This gives it a strong resistance to condensation, moisture, and fungal growth. Jute is a hard fiber which makes it very durable and jute burlap is wear, tear, puncture, and stretch resistant. Breathability plus condensation, moisture, fungal growth, wear, tear, puncture and resistance to stretching are all qualities which make burlap a good choice for the transport and storage of goods and as a geotextile.
“Natural” burlap is lightly treated with an emulsion, usually a cheap plant based 3:1 water and oil mixture, as a part of the weaving process. The mixture makes the fibers easier to handle and move through the loom, and helps reduce waste. The water does most of the work; the plant-based oil just prevents the water from evaporating so quickly. Burlap made with plant-based emulsion is required for food safety, storage and transportation and aren’t as long lasting as the other type of burlap. They normally last about three years in use but can take up to a decade to decompose.
Yes, you read it correctly.
“Natural” burlap can take 10 years to fully decompose.
The qualities that make burlap good for food stuff transport also make it useful in the construction, landscape, government/emergency services, and outdoors/sporting sectors. Fabric woven for use in these areas is treated differently; the emulsion used on it during weaving is usually petroleum based. This emulsion is designed to add more water, rot, and gnawing pest resistance to the fibers prior to weaving. It can leave the fabric feeling “sticky” or “coated” and tends to attract dust and dirt. It also has a peculiar chemical aroma to it. The finished fabric is often treated again to add even more resistance. So, the fibers are treated prior to weaving and then often again afterward. A double whammy, so to speak. “Treated” burlap is very long lasting, durable and can be stored for years in a variety of conditions without the fibers weakening. It can last for decades, above and below ground.
Which brings us back around to B&B trees.
Guess which burlap is used almost exclusively in the landscape industry, the “natural” or “treated” ?
If you guessed “treated,” you’re correct! Its durability, ease of use, and excellent storage qualities makes it the #1 choice for transporting nursery trees.
Unfortunately many, if not most, plant people don’t know about different burlap types and are relying on out-dated information. (This is true in more areas than just burlap, but those are other issues.)
Try asking if the burlap on that root ball is “natural” or treated and see what their response is. Feel the fabric yourself. Does it have a tacky feel, do your fingers drag on it, does it seem to attract dirt or dust? Does it have a chemical or petroleum odor to it? These are all indicators of treated burlap. Both natural and treated burlap degrade slowly. Leaving burlap on the root ball will only encourage circling roots and probably doom the tree.
Just so we’re not being misunderstood: Wrapping the root ball with burlap for transporting purposes is all well and good.
But you have to remove it at planting!
Let’s do a quick review of the qualities of burlap and how they can backfire when planting trees.
Breathability: not really a problem underground but can cause the root ball to dry out if the tree is exposed to the air for too long.
Condensation and moisture resistant: doesn’t absorb water so the fibers won’t rot.
Little to no fungal growth: isn’t consumed by fungi so fibers stay intact.
Tear and puncture resistance: roots can’t push or force their way through therefore encourages circling roots.
Doesn’t stretch: won’t expand with root growth therefore encourages circling roots. Sound familiar?
“Natural” burlap: can take up to a decade to completely decompose all the while negatively impacting root growth.
“Treated” burlap: can take decades. ‘Nuf said.
Soil factors can also influence burlap decompostion. The decay rate in soil pH levels below 6 is significantly slowed. Low soil temperatures result in a slower decomposition process. Dry soil slows jute fiber break down too and even desert termites don’t care for treated burlap.
A B&B tree is an investment: give it the best possible start you can. Always remove the burlap, wire basket, strings, ties, or any other constrictions you find. And don’t forget to root wash, correct any root problems, and spread the roots out horizontally away from the trunk when planting.
For your enjoyment, be sure the sound is turned up so you get the full effect.