Expert: Jim Hyland - 4/18/2007

Question
QUESTION: Hi. I am hopping that you can help me with my pine needle situation. I live in a townhouse and along my cedar fence I have about 12 pine trees that shed needles all year round. The trees are old and provide a lot of shade in the hot summer months but they often look brown in color. Is there something I can do to help them look better. Also about the needles. They are an awful mess but I was told they provide nutrients to the trees. Should I remove them or are they good for the trees. The ground the trees are in was once a swamp before the communities were here. I end up with a lot of moss under the needles. Any advice on what to do?????
ANSWER: Leaf drop is normal if the drop is the older needles and there ar still green needles present. If the whole tree is starting to yellow I would recommend that you fertilize the trees  
In some years, the natural needle drop will occur in a relatively short period of time, with rapid and noticeable browning of the older needles, which leads to fears the tree is dying. In other years, people don't even notice it happening, because the browning is spread over a long period of time.

The symptoms are normal for the fall. Pines and arborvitaes normally shed their oldest needles in the Fall. White pines usually retain their needles for one to two years. The older needles, those towards the center of the tree, turn yellow before dropping. Older arborvitae leaves turn a reddish brown. Natural needle discoloration may be more noticeable on trees that have experienced root stress due to less than optimal growing conditions. Extended dry periods during the summer months, as well as sites with poorly drained, heavy clay soils may accentuate root stress to pines. Since the newest growth (this year's needles) are still green and healthy in appearance, you can be assured that this yellowing phenomenon is a natural one.

To improve the growing conditions around your trees you may want to refer to HO-140, Fertilizing Woody Plants (PDF file). In addition, deep-core aeration may help improve root growth by improving the soil structure and the percolation of water into the soil. To apply one inch of water a week (the minimum needed during drought periods) you may need to run a hose and sprinkler or soaker at full capacity for 1.5 hours under the branch spread (drip line area).

What can I do with the pine needles that have fallen?  Don’t bag ‘em; use them!  The fallen needles make excellent mulch for many of your landscape plants.  


For larger trees in open areas, about 2 pounds of 10-10-10 fertilizer can be applied for each inch of trunk diameter of the tree.
Fertilizers are best applied in late August through September. Root absorption of nutrients is very efficient in late summer and remains so until soil temperatures approach freezing. Nitrogen that is absorbed in fall will be stored and converted to forms used to support the spring flush of growth. The next best time to fertilize woody plants is early spring prior to initiation of new growth.


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QUESTION: Thank you for your answer to my question. The needles do not allow for any other growth under the tress. They are large and moss grows under them. Is there any way to have any other thing grow under them?
Also my husband would like to use landscape edging were the grass ends at the edge of the pine trees branches, if we do this he wanted to use round smooth rocks under them. Would it be better to rake the needles and just let them sit on the ground under the trees? Also to use the needles as mulch, what plants and tress can I use it with, is there anything that I should add or do the needles before using them??
Please help, Thank you  

Answer
The idea of mulch is to keep anything from growing under it--pine needles work well for this. You can use the pine straw around any plant that you want to keep the weeds from growing and hold moisture. They are used around shrubs around houses to not only make it look good both for weed control. You do not have to add anything to the needles.
The rocks will not hurt the tree as long as they are not too thick--not more than 3 inches. If the weight presses the air pockets from the soil it will effect the roots. I would rake the needles before placing the rocks.