Know what not to do in home landscape

By Phil Sell

This is the second of a three-part series on common, recurring landscape maintenance mistakes that I have encountered during my 34-year career with K-State Research and Extension. I hope you will share my concerns with others who may not see this column.

As mentioned in the first segment on June 21, I have emphasized the negative aspect of these practices so you won't misconstrue my pointed admonitions.

Improper pruning

It's a mistake to "top" trees by making indiscriminate stub cuts to shorten branches that are larger than three inches in diameter.

Topping creates wounds that won't heal, disrupts the carbohydrate balance in the tree, causes weak branches to originate from shallow adventitious buds that are then subject to breakage, and suddenly exposes the topside of branches that were previously shaded, contributing to sunscald. Finally, topped trees are ugly.

It's a mistake to shear shrubs into formal geometric shapes ("boxes and balls"), except for the specific purpose of creating a topiary plant or formal hedge.

Shearing is self-defeating because it must be repeated on a regular schedule, it looks unnatural, and the numerous pruning wounds may provide a place for diseases to get started. If shearing is required to keep a plant in bounds, consider replacing that plant with one that will fit the available space at maturity.

It's a mistake to prune early spring flowering shrubs before they bloom or potential flowers will be removed. Prune these plants immediately after flowering in the spring.

It's a mistake to prematurely cut the foliage off hardy spring flowering bulbs. Wait until the leaves die back naturally to allow the plant to replenish stored food reserves.

It's a mistake to apply a wound dressing or pruning paint to cut surfaces (with few exceptions).

Improper plant spacing/landscape design

It's a mistake to plant shrubs too close together in a residential landscape. Always consider their mature size.

Shrubs should be spaced apart at a distance that is one-half of their combined mature diameters, and away from walls a distance of one-half of their mature diameter, plus one foot.

Consult nursery catalogs or Extension publications to determine mature spread.

It's a mistake to plant trees where they may grow into conflict with overhead utility wires.

It's a mistake to group plants with different moisture requirements together. Doing so complicates proper irrigation and results in some plants being overwatered while others suffer from moisture deficiency.

It's a mistake to plant a ring of annual flowers around the base of a tree. Doing so prompts frequent watering at the base of the tree, to support the flowers. This can contribute to basal decay or root rot on the tree.

Also, roots may be inadvertently damaged while trying to dig holes for the flowers, providing an entry point for root rotting fungi.

From a landscaping standpoint, this practice creates misplaced accents, drawing attention away from more important elements in the landscape.

It's an even worse mistake to build a raised flower bed around the base of a tree. This causes soil to be in contact with the bark on the lower trunk, which causes moisture to be retained there, potentially contributing to decay. Piling mulch around the base of a tree may cause the same problem.

Construction damage to trees

It's a mistake to inadvertently damage existing trees on a building site during the construction process. Obvious damage may result by cutting tree roots while digging trenches for foundations, footings, or underground utilities. Don't dig within the critical root radius, an area defined by the size of the tree to be protected. A trained arborist can apply the appropriate formula to calculate radius.

Careless operation of heavy equipment can damage bark and scaffold branches on trees.

Other, more subtle problems may be caused by:

• Changing the grade around trees by removing soil to lower a grade, or by adding soil to raise a grade.

• Compacting the soil over the root-zone of trees with delivery trucks, heavy equipment and personal vehicles).

• Installing pavement or other impervious surface over the root-zone, such as a patio or driveway.

Pesticide misuse

It's a mistake to spray plants with insecticides on an arbitrary, predetermined schedule. Insecticide sprays should be used only in response to a legitimate threat targeting an insect population that is in a vulnerable stage for control.

It's a mistake to get pesticide or fertilizer granules into the street where they have a direct conduit, through storm sewers, to surface water downstream. If chemical particles are accidentally thrown into the street, sweep up and reapply, or blow back onto the lawn.

It's a mistake to apply pesticides without first consulting the product label. Read, understand and follow label instructions, precautions and restrictions each time you use a pesticide.

It's a mistake to spray herbicides under conditions in which they can drift off target and damage desirable plants in the vicinity. Apply herbicide sprays when the wind is calm, keep the spray nozzle close to the ground, and adjust the spray pattern to deliver coarse droplets, not a mist.

Phil Sell is a retired agent emeritus with K-State Research and Extension.