Tips for Specific Landscape Plants

Below is a list of additional care tips for some specific plants. This is only a guide.  If you have questions about the health or well being of your plants, please visit one of the horticulture experts at Kennedy’s.  If it is a potential insect or disease problem, it might be a good idea to cut off a branch of the plant and let the staff at Kennedy’s get a look at a fresh sample.  Or bring in photos.

 

Grasses and Perennials

Most Grasses and Perennials should be cut back every year almost down to ground level.  The preferred time to do this is in late winter or early April before they begin to grow again.  Many of these plants may have aesthetic value during the late fall and winter.  In addition, many perennials benefit from the foliage and leaves that collect around the plant, which give them added insulation and protection from extreme weather conditions.  If you prefer a cleaner look in winter, you can safely cut these plants down in late fall.  For added insurance, Kennedy’s recommends applying a minimum two inch layer of salt marsh hay around perennials and grasses in the late fall.  This is especially helpful for plants going through the first winter in their new surroundings.

 

Perennials with Woody Stems

Perennials with woody stems such as Russian Sage and Lavender benefit if you leave at least 1/3 of the woody part of the stem sticking up from the ground.

Broadleaf Evergreens

Plants such as Azaleas, Boxwoods, Rhododendrons, Mt. Laurel, Japanese Holly, and other plants that fit the category of broadleaf evergreens may benefit from extra protection in the winter.  These plants are particularly tender during their first winter in your landscape.  Sunny, windy, exposed situations are the most problematic.  These plants are also more sensitive if they have been planted in the fall.  One form of protection is the use of an anti-desiccant spray.  This type of product is similar to wax and it helps protect plants from losing too much moisture.  The best time to spray is a warm day in December.  Sheltering the plants with burlap is another excellent option.  Some customers do both. Watch Andromeda (Pieris), Azaleas, and Rhododendrons for lace bugs (loss of color on leaf).  The leaves overall look yellow, but if you look more closely it looks as if someone took a yellow pen and tapped the leaves to give it a spotted appearance.  Lace bugs hide under and attack the under sides of leaves when weather is warm (June thru September).  It is a difficult pest to kill with a bug spray.  Usually it is best to use a systemic insecticide to ensure you get thorough control of this difficult pest.  It may be best to bring a sample into us to diagnose and get a good recommendation.

 

Hydrangeas

Since many varieties of Hydrangeas flower off last year’s woody stems, avoid pruning them back.  If pruning is necessary to control size or shape, they can be pruned lightly, immediately after flowering.  See Kennedy’s Hydrangea handout for more information.

 

Fruit Trees, Birches, and Maples

Monitor Birches, Maples, Roses, Flowering Crabapples, Cherries, Plums, other trees in the fruit family for caterpillars.  Look for holes in the leaves, particularly during early spring.  Spray as needed with an organic bug spray.  Consult with our expert staff for the most current information. Birches are also susceptible to attack by borers and leaf miners.  Borers pose a serious threat and can kill the tree or at least the trunk or branch that they attack.  Look for little entry holes in the bark of the tree, especially during warm summers or times of stress.  Consult us if you find a problem.  Leaf miners are not as serious, but can become a problem if unchecked.  Look for leaves turning brown in the spring.  With close inspection, you can see the worm inside the leaf eating it from the inside out.  A systemic insecticide may be necessary for either insect.  Consult the experts at Kennedy’s for the most current information.

 

Boxwood

Boxwood is susceptible to an insect called a psyllid.  When you shake the branches a white powdery substance flies in the air.  Psyllid can be easily treated with a general insecticide such as “Eight”.  Consult us at Kennedy’s for details.

 

Euonymus and Cherry Trees

Monitor Euonymus and Cherry trees for an insect called scale.  Scale is an insect that attaches to the bark and draws the sap from the plant and cause the plant to decline if not treated in a timely fashion.  Look for a white (usually) substance coating the bark and branches of the plants.  Horticulture oil or a systemic insecticide will work on these pests.

 

Austrian Pine

Austrian Pine (Pinus nigra) is generally a very durable tree.  They are typically very wind and drought tolerant after they have been properly watered and cared for for a year or two.  Austrian Pines should be monitored for boring caterpillars.  Look closely at the bark of the trees monthly, (May-September), for entry holes in the bark, often on the main trunk near the top half of the tree.  If the entry holes are fresh, you can often notice the sawdust as if someone just drilled a hole in the tree.  Results of a borer can cause the tree to decline and kill the tree from the entry hole up to the top of the branch or trunk.  If you notice any bronzing of the tips of the branches in the summer time, it may be borer.  There are a few other less common and harder to diagnose problems with these pines, please consult us if something appears to be unusual.

 

Hemlocks and Alberta Spruce

Hemlocks (Tsuga Canadensis) are plants that have received a lot of attention from those in the horticulture field.  A particular insect called hemlock wooly adelgid has made news since the 90’s.  These insects are readily identifiable by examining the plants on a monthly basis.  An insect infestation occurs randomly.  They look like snow on the branches if you look closely.  It is usually recommended to use a horticultural oil spray to suffocate this insect.  Another way to rid the plant of the wooly adelgid is to use a systemic insecticide such as Merit.  Please consult us or pick up one of our handouts for further information.  Hemlocks are also sensitive to dry soil conditions.  Please be sure to give your hemlocks plenty of water, particularly right after they are planted and during any prolonged times of hot, dry and or windy weather. Hemlocks and Alberta Spruce are susceptible to infestation by red spider mites.  These mites are tiny and almost too small to see.  They damage the tree in the summer months when the weather is warm.  If you see webs and a slight to severe bronze cast the needles it is probably spider mites.  These can be treated with an insecticidal spray.  Please consult the experts at Kennedy’s.