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Planting Guide for Woody Plants (Trees and Shrubs)

If you’ve never planted a tree or shrub, you should not be intimidated, but you should know that it is more than just digging a hole and sticking the plant in it. Technique matters.

We have given away this free one page planting guide at Urban Earth for years.

Field grown Emerald Green Arborvitae with the root ball wrapped in wire and burlap (bnb).

Woody plants, trees, and shrubs come in either a container grown form or a root ball wrapped in burlap. Container grown plants tend to cost more than ball in burlap (bnb) but are usually worth the extra money. This is because container grown plants come with a fully intact root system. In contrast, bnb plants are grown in a field and then cut out of the ground by the grower when it is time to ship them to a retailer. As such, in comparison to container grown plants, the ability of their root system to take up nutrients and water is impaired for at least the first few months after planting.

Since the majority of the plants Urban Earth sells are container grown plants, which are better for most consumers, this guide

Container grown plants, like these beautiful Awabuki Chindo Viburnums, cost a bit more than bnb plants but are well worth the extra money.

assumes the reader is planting a container grown plant.

 

Right Plant, Right Spot

The first step is to pick a good spot. The number one reason plants fail is because plant and location are not properly matched. Plants differ in the number of hours of sunlight they need, the frequency with which they need watering, whether they tolerate wet feet, and their preferred types of soil. For best results, work with our sales staff to make sure the plant you are choosing is appropriate for the spot in which you intend to install it. For them to help you, you will need to know whether the spot is on the North, South, East, or West side of your home, whether the spot is sheltered from Western winds, whether the spot is low with frequent standing water or higher than the rest of the yard, etc.

In this midtown landscape makeover, planted in winter, notice how garden designer, Jesse Howley, picked a spot for this coral bark maple and this holly where they get full morning sun but also get shelter from western winds, planting both slightly high for good drainage, and mulching with pine needles. Right plant, right spot.

Digging the Hole

My drawing skills are terrible! But, this might help illustrate my explanation.

The next step is digging the hole. The hole should only be dug when the soil is friable. To test for friability, pick up a handful of the

Our Hisco long handled garden spade is ideal for taller gardeners or those needing more leverage.

soil and throw it against a hard surface. If it breaks apart into smaller pieces, it is friable. If it splats, looking like a pancake, it is not friable and should be allowed to dry out some before digging. If you dig a hole when the soil is not friable, the sides will become sealed by the shovel as you slide it into the ground, possibly preventing drainage and slowing root growth, becoming like a terracotta pot.

The shape of the hole should be a shallow bowl with a diameter at least 3 times the size of that of the root ball. This will allow water to penetrate the surface better and give new surface roots an easy space into which to spread. For example, if the plant came in a trade 3 gallon container, the most common size in the nursery trade, it likely has a root ball with a diameter at the top of 10 to 11 inches. So, the top of your bowl-shaped hole should be 30-33 inches across, with sloping sides tapering down to 10-11 inches at the bottom.

A high quality commercial grade shovel, like our d-handled Hisco garden spade, is an essential tool for every home owner and gardener.

The hole should be no deeper than minimally necessary to accommodate 80% to 85% of the height of the root ball. For example, if the plant comes in a trade 3 gallon pot, it likely has a root ball that is about 10 inches high. Accordingly, the hole should be about 8 to 8.5 inches deep. Upon completion, the plant should sit a little high, to promote drainage away from the trunk rather than water pooled around the trunk.

Avoid the temptation of digging the hole deeper than necessary and filling back in with what you consider better soil, “for the tap root.” Past the seedling stage, woody plants rarely send roots down, instead sending them out to the sides. Hence, horticulturalists often speak of “the tap root myth.” And, if you dig deeper and then back-fill to bring the root ball back up, there will be settling, meaning the crown of the root ball, where the roots connect to the trunk, may end up below grade, rather than above grade, with the passage of time.

This is in contrast to what many garden guides will tell you, stating that the hole should be deeper than the root ball. For example, the 7th edition of the Mid-South Garden Guide (MSGG), which I consider to be a brilliantly written guide, definitive in most matters, states, on page 36, “Dig a hole a little deeper than the root ball and at least twice as wide.” Though gardening is not known for fast changing, cutting-edge thinking, the gardening community does change its mind about things. Thus, most competent landscape installers I know have evolved in their thinking on this and dig the hole only as deep as necessary, but a bit wider than this quote from the MSGG might imply.

The Mid-South Garden Guide, a classic text that are proud to carry, currently in its 7th edition, is essential for every Memphis gardener.

Putting the Plant in the Hole

After the hole is dug, remove the plant from the pot by grasping the base of the trunk, right at or slightly above the crown, while holding the pot in place or sliding it out. If it doesn’t come out easily, squeeze the sides or even gently pound the sides a bit to loosen it up. If it still won’t slide out easily, use a box cutter to cut the bottom off of the pot and then slice up the side to separate it from plant from pot entirely.

NOTE: Roses are different than most other woody plants. They have a much more fragile root ball and should always be sliced out of the pot with a box cutter, first slicing off the bottom and then placing the plant in the hole before slicing off the slides of the container. The backfill content for roses should also be different and is beyond the scope of this guide.

After removing the plant from the pot, gently loosen its root ball. If it is significantly root bound, with girdling roots (thick roots circling all the way around the root ball) you may want to do some light pruning or cutting of the roots with shears or a pruning saw to open up the root ball a bit. But, don’t go over board with this! Generally, the horticultural community does less severe root ball loosening than it used to do.

Then, place the plant in the hole, with about 15% to 20% of the root ball above the existing grade so that water will drain away from rather than towards the trunk, post planting. Keep in mind that, though roots are designed to absorb water, the cambium layer forming the outside of trunks is not designed to absorb water. Water pooling and sitting against a trunk will eventually cause damage to the outer cambium layer and impair the plant’s ability to take up nutrients.

Putting Soil in the Hole

A good recipe for soil back-fill for woody plants is half of the original soil, half Fox Farms Original Planting Mix, and a 1/4 cup of soil sulfur, well mixed.

There is much written about the ideal soil amendments for planting. In fact, there is an entire chapter on the subject in the 7th edition of the MSGG! And, many suggest that you should always have your soil tested in a laboratory to see what it needs before planting. But, I am currently advising all of our customers to back fill the hole around the plant with a mixture composed of 50% Fox Farms Original Planting Mix, 50% of the original soil, and a quarter cup of soil sulfur. Unless you are doing a wholesale re-landscaping of a significantly large portion of the yard, spending hundreds or even thousands of dollars on plants, soil testing adds a layer of difficulty to the task of installing a plant or tree that will only occasionally be rewarded with better results. Similarly, though custom mixing soil from raw ingredients may produce better results for experienced gardeners, most of the time the Fox Farms Original Planting Mix is superior to anything you could mix up yourself.

As you place your soil mix back in the hole, gently press it down around the root ball, adding more as necessary, being careful to keep it from piling against the trunk. When finished, the soil should slope gently away from the root crown, where the roots meet the trunk. Most trees, and many shrubs, will have a slight flaring of the trunk right above the root crown. That part should remain visible.

It would be hard to match a mix of this quality with a home brew soil mix. Though the harvesting of bat guano can be damaging to the habitat of bat populations, our Fox Farm representative has assured us that they use only fossilized bat guano from caves not currently occupied by bats.

In fact, when arborists are called to inspect struggling trees in the ground for less than 2 years, that is often the first thing they notice, that the trunk flare is missing, because the tree was planted too low, causing a gradual breakdown of the outer cambium layer, where the tree’s vascular tissue exists, home of the pathways through which nutrients travel up the trunk from the roots.

Finally, drench the tree with water, perhaps more than you might regularly water with, to get any air pockets out and to rehydrate the roots from any drying that has occurred during the trip from the nursery to the hole. Add more soil if necessary because of settling after watering.

Mulch and Maintenance

After planting, mulch with the 3 to 4 inches of fresh pine needles or 1 to 2 inches of wood chips or bark mulch. For more information about mulching, please read my blog article, “Mulch Ado About Nothing,” in which I explain why pine needles are superior to other mulches. The purpose of mulch is to help reduce weeds, slow the evaporation of moisture from the soil, and give the ground around the plants a uniform appearance.

Going forward, most plants benefit from an application of 12-6-6 granular time-release fertilizer, every spring and fall, or a monthly application of one of our Happy Frog organic fertilizers. I also advise an annual application of soil sulfur, which I usually do in the fall. Some people advise mixing fertilizer into the back fill when planting, initially. Even I will sometimes do that, but newly installed plants are more sensitive to over-fertilization and there is usually adequate nutrition in the soil they came in, combined with the Fox Farm planting mix I described above, and existing soil. If you use the Fox Farm Planting Mix, you will not need to mix in any additional fertilizer into the soil.

Remember, though most soil has a tendency to revert to a neutral ph over time, most woody plants absorb nutrients and water better when the soil is at least slightly acidic. Soil sulfur is a natural and gentle soil acidifier. While soil can be made too acidic for many plants, it is harder to make a mistake when using purely organic ingredients, which are slower acting than purely synthetic products. Soil sulfur is a natural fungicide, and often cures many nutrient deficiencies in plants, since nutrient deficiencies occur most often, not because the nutrients aren’t in the soil, but because the plant can’t pull those nutrients from the soil if the ph is too high (alkaline). Since sulfur is a negatively charged particle, an anion, it also does not bind with negatively charged soil particles, making it more vulnerable to leaching, needing more frequent replenishing.

 

A four pound bag of soil sulfur costs well under $15.00 ($11.99 at the time of this writing) and is essential for every gardener to have in her shed.

John Jennings, Author and Manager

The author, John Jennings, has been manager of Urban Earth Garden Center since June 1, 2016.  Before that he was a self-employed landscaper for 8 years, having worked as both a real estate lawyer and a drug counselor in previous lives. He grew up in the South Carolina low country, learning to garden in the fertile soil of Copes Island, a small barrier island near Beaufort, in Jasper County. John is a graduate of the McCallie School, the University of Richmond, and the University of Memphis Law School. If you read this blog entry, please email the author at john@urbanearthmemphis.com and let him know what you think. 

 

 

 

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