Proper Planting or "Digging a Hole"

There is a lot of literature devoted to the actual act of digging a proper hole for plants, from annual plants to trees. I especially love the descriptions that have pictures showing the perfect hole, excavated just so, with vertical sides and horizontal bottoms. The soil is also amended to compensate for whatever its deficiencies are. In a perfect world this would be exactly how it is done each and every time. Because it is not a perfect world and because there are instances where compromises have to be made, the perfect hole is an ideal and not always practical for the myriad of exceptions in the real world.


To start, a perfect planting hole is twice as wide as the ball/pot of the plant and at least as deep as the depth of the same ball. The theory is to loosen the soil so the new roots have space to grow. It is especially important if the soil has recently been compacted by construction machinery driving over the soil due to recent construction on the site. Compaction is problematic especially if there is a heavy clay component. Clay particles, unlike sand, are very small and can be squished together forcing out air spaces in the soil profile. The soil profile extends the depth of the root ball and adding a soil amendment, like peat moss or leaf compost, etc., to the depth of the profile is, basically, consistent with adding these pore spaces back in. It is also an opportunity to add nutrients directly to the area where roots are growing. Too much soil amendment can be counter productive though because the backfill needs to be tamped down to provide support for the plant and prevent it from tipping over. Too much amendment will make the backfill composition too spongy and difficult to tamp sufficiently.


A less than perfect hole needs to be at least as deep as most of the depth of the root ball and wide enough to allow for rotating the root ball to find the best side of the plant. Will the plant die if the hole is not twice as wide as the ball of the plant? Will the plant die if the soil does not have enough organic material? Will the plant die if the hole is not deep enough? Read on.

The literature on planting practices is all about what is recommended but it is not the final word. If you can't dig the perfect planting hole, don't sweat it. Plants really have a stronger ability to survive less than perfect conditions than you might think. I have seen trees growing through cracks in concrete and along the face of a cliff. I have seen shrubs ripped out of landscapes only to be replanted somewhere else after sitting on the back of a truck in the hot sun all day and survived, in fact, thrived. Granted, some plants are more sensitive than others but there would be a LOT more dead trees and shrubs if they had no tolerance of less-than-ideal conditions.

Every plant goes into a period of “shock” after transplanting, which is simply an adjustment period where there is no apparent growth. There are multiple biological processes activated to protect the plant after transplantation that are not obvious to the naked eye but knowing this makes treating plants with exceptionally good post transplant practices a logical and prudent next step.

So to get started:

1. Dig a hole: Dig a hole wider than the root ball, ideally twice as wide but whatever can be managed. Dig the hole only as deep as the ball but a bit shallower is actually preferable. The plant will settle under its own weight and it is problematic for plants to be buried lower than their existing soil line. This is a common planting error. Roots need air circulation and planting too deep upsets this balance. I use the head of the shovel as a measuring stick. Setting it next to the root ball makes it easy to dig a hole deep enough by using this rough measure noting where the soil line on the existing root ball falls. Then I use the shovel head's width to estimate how wide the hole needs to be, like one shovel width, 1.5, 2 etc. Ultimately, the hole provides a space to anchor the plant so these rough estimates are adequate.
   
   Burying the “root flare” of a tree has long been an industry conundrum. It is recommended to find and expose root flares, which is where the transition point is from trunk to roots characterized by an overall widening of the trunk, that may have been buried during the root pruning process in the tree nursery when the machine throws soil back up against the trunk of the tree. While burying the root flare does not kill a tree right away it creates a situation that the tree can not overcome and it will compromise it's long term survival ability. The tree will simply continue to decline from year to year until it eventually dies. I routinely see a row of trees planted along a roadway or driveway and notice a percentage that are not growing as well as the others. Commonly they are the ones whose root flares have not be excavated at the time of planting and they are just slowly fading away as the other trees thrive.
   
2. Planting procedure: Take the plant out of the pot, cut the twine, unwrap the burlap, remove the wire. As this is being done, it is important to maintain the integrity of the ball of soil. If the ball seems loose, try to stabilize it by placing it in the hole and then removing the potting materials. The less damage done and the greater quantity of roots preserved, the better. Roots are critical for water uptake so it is imperative to keep them as intact as possible.
   
3. Situating: Before back-filling the hole, make sure the “best” side of the plant is facing where it will be noticed. Yes, this is subjective. Yes, it involves looking critically around the plant. If there is a bare spot or broken branch or hole, let it face the house or away from where you will be looking. There is no real right or wrong because nature will take over and balance things out. No one comes around after and criticizes that the “best” side of the plant is facing the garage.....All I am saying is take a minute and look.
   
4. Backfilling: The next thing to do is to break up the clod of soil that was originally dug out of the hole. It is at this point that the soil can be amended with leaf compost, peat moss, sand or nothing. Next step is to backfill the hole. Press dirt into the space around the sides of the root ball and then press or step around the plant to make sure the soil is tamped down to make good soil-root contact and prevent it from tipping over. Take care NOT to mound the remaining soil up around the trunk of the plant but rather spread it out in some other part of the garden. I usually leave the remainder of the soil in the pot and then find other places around the yard to fill in holes or places to spread it out.
   
5. Staking: For top heavy plants, staking is the next step to minimize the incidence of being tipped, blown, or knocked over. There are lots of new materials to facilitate staking and their sturdiness needs to be directly proportional to the size of the plant being staked. The one caveat is to make sure to protect the bark of the plant being staked. The vascular part of plants is right under the bark. If the bark is damaged or removed the health of the plant will be compromised. When a tree is staked, leaving the bracing too loose will not stop the wind from allowing the bracing to rub the bark right off of the plant. If the bracing is too tight it can actually crush the vascular tissue. Another industry conundrum involves removing the staking materials after the first growing season to prevent damage. It is rarely put into a contract to have the materials removed after the first year and it is not uncommon to see staking materials compromise the long term health of the plants they were installed to protect.
   
6. Mulch: It is common to see mulch placed around newly planted trees and shrubs. Shredded hardwood is the most common type of mulch selected due to its cost and availability and its relative ease of handling. Mulch slows the rate of evaporation shielding the root ball from the sun. Equally important is mulch shades the soil sufficiently to prevent weed seeds from germinating. Unless you like weeding, this is an important next step. When soil is disturbed it dredges up new weed seeds waiting for primo conditions to grow, and they will. What mulch to select is subjective. See what the garden center has in stock and have fun.
   
7. Water: The very most important thing you can do for the plants is to water, water, water. Do not wait for it to rain, do not pay attention to the forecast. Plants cannot get too much water during this period, especially in the first few days after transplanting. One of the biggest mistakes people make is waiting until the next day to water or worse thinking it will rain and the rain never comes. Frequently shrubs that are guaranteed or warranted will be voided due to improper watering. Plants installed in the spring will require regular watering through the summer and into the fall when typical rainfall patterns kick in and temperatures drop. If this is more than you can handle then don't plant anything in the spring or summer. Wait until the fall when typical rainfall will help you out. You will still need to water everything in after transplanting but if temperatures are cooler the rate of evaporation will slow down and the fall season supports root growth.
   

There is literature that suggests and experiments that demonstrate that when trees are planted according to the textbooks they actually do grow better in the long run. These experiments show that plants establish faster and are measurably bigger than their counterparts over a sequence of growing seasons. It is important for professionals in the industry to know this and do the best they can to pattern their practices after it. It is a tad more difficult for the homeowner who is planting with a shovel and using their sweat equity to muscle plants into compromised sites that may have been compacted due to construction. Just do the best you can.