Taller Grass has More and Deeper Roots

Years ago I observed an experiment where lawn grass was grown in pots and cut at various lengths. After 6 months soil was washed from the roots and dry weight was measured. The grass cut at 2 inches had twice the weight of roots as the 1 inch cut. Then a year or two later I observed another experiment where the grass was grown in soil with a glass wall so the roots could be observed in an underground cellar. You guessed it, the root system depth was in direct proportion to the mowing height. The two inch cut had twice the depth of roots as the one inch cut. If all other maintenance practices are equal, the higher cut lawn will always look better than the one cut short. Higher cut is more important as weather gets hotter.

But, you say, golf course grass is cut short, and it looks great. And golf courses spend a lot of time and money on extra fertilization, pest control, aeration, top dressing, and over seeding to keep the short cut grass looking great.

Protect Trees from Stunting and Death by Trimmer

The line trimmer has become almost as common as the lawn mower for landscapers and gardeners. It gives lawns that finished touch with all the edges neatly trimmed. Young trees with thin bark are particularly sensitive to damage from line trimmers. Trimmers make little nicks and cuts in the bark which can gradually cut all the way through. The inner bark contains the tubes which transport food made by the leaves to the roots. If these tubes are damaged, root growth is reduced and top growth becomes stunted. Completely cutting bark all the way around will kill a tree. Maintaining a circle of mulched soil around young trees will not only protect trees from damage, but reduce competition for water and nutrients, resulting in faster growth.

Soil Improvement – Incorporate Bark

Bagged and bulk outdoor planting soils are becoming more widely used. They are recommended for planting flowers, vegetables, over seeding lawns and planting trees and shrubs. Incorporating bark or other organic amendments into existing soil is cheaper and usually more effective. Tilling in two inches of bark dust will provide as much improvement as applying 6 inches of soil mix. Bark dust is just as effective as bagged mixtures for mulching over seeded grass. Soil mixes are appropriate for containers and raised planter boxes or other areas where soil level needs to be raised 6 inches or more.

Summer Fertilization

We have had good growing conditions for plants this spring and most plants are green and healthy. If some of your flowers, vegetables, trees or shrubs are losing their vigor and dark green color, they may need an additional application of fertilizer. Flowers and vegetables which were planted and fertilized 2 or more months ago may have used most of the fertilizer which was applied. This is particularly true for container plants. They are watered more frequently and fertilizer is washed out of their more limited soil volume. I like to apply coated, slow release fertilizer such as Osmocote to container plants and to rapidly growing vegetables and flowers.

If you are continuing to irrigate your lawn and its color is fading, an application of lawn fertilizer which contains some slow release nitrogen may help. You will need to check the “guaranteed analysis” to see if part of the nitrogen is in slow release form. Iron also helps to improve leaf color.

Plants can be burned by fertilizer applied during hot weather if the soil is dry when it is applied. Make sure the soil is moist or water before application. Plants should be watered again after fertilization to dissolve the fertilizer and make it readily available. Liquid fertilizer applications seldom cause burning because water is added at the same time as fertilizer.

Choose Plants Carefully to Avoid Future Problems

Client Question: Seven years ago we purchased a new home and had it landscaped professionally. The shrubs were attractive for the first few years until they began to grow too wide for the walkways and too tall for the windows. Now they have lost all their individuality and have become square or rounded hedges. Is it too late to remedy our situation or do we just need to tear them out and start over?

Answer: Your situation is quite common. Small shrubs are often planted close together so they give a more immediate effect. They soon grow together and lose their individual identity. Shrubs are planted which have a mature size larger than the space where they are planted. Soon yearly pruning is needed to keep them in bounds. When shrubs are pruned with shears or power clippers they form many branches and have very thick growth — like hedges.

It may not be too late to recover natural shape and thickness of your shrubs. I do this regularly. I also teach people how to prune their own plants so they have natural thickness and shape. If some of the plants had been removed when they first became crowded they would have been more attractive. Shears and power clippers will always produce unnaturally thick growth. There are a few shrubs which can be cut back to a foot above the ground. They will regrow with more normal shape and thickness.

The best solution to this problem is to re-landscape using smaller varieties of shrubs which require only limited pruning. Whether you or landscape professionals are selecting shrubs, they should be carefully researched to find their mature height and width. They should also be chosen for their climate zone adaptation and for their sun and shade preferences. Other qualities such as fall leaf color and flower production can also be important. Many plant labels contain this information. However, it is easy to check the internet for any plant name and find several references about a plant’s characteristics. Book stores, libraries and County Master Gardener offices have horticultural reference books.

Smaller varieties of trees and shrubs are widely available. These smaller varieties are often more expensive than larger, faster growing ones. In many cases they are available only in full service nurseries and not in the “Big Box” stores. They will give many years of satisfactory performance with more limited maintenance requirements and are worth the extra cost.

One of my favorite jobs is to design, select and plant new shrubs for an overgrown planting. If I can help you with any part of this process, please give me a call or email.

There Are No Dumb Questions

If you have a question about your plants or landscape feel free to ask. There are many others out there who have the same or similar questions. There is no charge for a phone or email response. I will occasionally include answers to individual questions in the newsletter so others can benefit from the information.