Root Pruning and Soil Replacements

Design and InstallationGarden Caregarden TriviaIndoor plantsPlant Health CareUncategorized
Written By Peter Morris

The Trees

 Plants evolved to use a volume of soil that is about twice their canopy and 24” deep. 

Street trees

 With this volume of soil of they are ensured to have enough water and minerals. It enables them to stay healthy and look their best. This mass will help insulate the roots from freezing, and allow them to pull water from a large reservoir when needed during a heat wave.An average street tree uses about 1,000 cu feet of soil – but what about a rooftop tree? 

Cherry tree on a rooftop in a huge lawn covered container (hidden)

The Buildings

 Think about that first sentence for a moment. Let’s take a 10’ Birch tree on a terrace that is about 6’ across. By nature, it optimally wants to be in a planter that is 12’ diameter x 2’ deep.The volume would be about 56 cubic feet. If using light weight soil at 55 lbs. per cubic foot – this planter will weigh about 3,200 pounds. The weight of an adult Hippopotamus. Need I say more.There is NO building in any city that will allow you to put this planter on a rooftop!Most building guidelines will only allow any one planter to weigh no more that 180 – 300 pounds OR LESS. It depends on the structural integrity and load capacity of that particular roof.A 2’ square planter – a commonly used size is about 6 cubic feet, and weighs about 300 lbs. 

The problem

 When we put plants into smaller than desired containers, we make a lot less soil available to them. The roots quickly use up all the free soil in the planter and the soil becomes compressed. We call this condition “root bound’. 

Compressed roots

 The compression stops new white roots from being produced. These are the ones responsible for taking up most of the minerals and some of the water!All trees suffer - they become stressed and weak. This attracts insects and diseases which further weakens them. Their leaves get smaller, pale or yellowish, and the tree produces fewer flowers and leaves. 

The solution

 Basically dig a hole ! - something we call a – “Root Pruning and Soil Replace”Simply dig into the container at the four corners removing soil and roots and replace with fresh new soil and fertilizer.Avoid any roots thicker than your pinky.Avoid any irrigation lines or lighting wiresRemove no more than a quart size of soil per hole Images showing the progression of a root prune from digging out old soil to closing. The roots will form new white growing roots and consume all the new soil and fertilizer in a few months. You will need to do this every year to alleviate the compaction. Rotate the places you work the soil every year. 

New white roots

All deciduous trees benefit from a soil replace every year - once in Spring and again in Fall.

Evergreens - once a year and only during Spring.

Call us if you need help ! 

PLANT SPECIALISTSGREENING NEW YORK FOR OVER 53 YEARS !

   Article written by our Staff Horticulturist, Peter B Morris, BSc, MSc, MBAAll photographs used with permission @SHUTTERSTOCK

Peter Morris

Peter was born and raised on a beautiful green island in the midst of a tropical rainforest. He was introduced into the world of plants at the age of six when his grandmother, an avid Spanish gardener herself, asked him to help her grow seeds for her pepper garden. He was hooked! By the time he was a teen, he had his own rose and orchid collection numbering in the hundreds. Botany was in his blood, and that is what he set out to study.

His passion brought him to NY in the late seventies to further his education. His tenacity allowed him to work full time at Plant Specialists while he completed a MS in Plant Biology. As a manager at the time he felt unsatisfied with his knowledge of business and business processes. Peter felt compelled to learn, so he then pursued and completed an MBA in Quality Management within a few short years.

Peter’s other passion is teaching. His natural ability is quickly consumed by our staff in all subjects in Botany, Horticulture, and Landscaping. He created an immense reference library of more than 3,500 plants providing an invaluable resource for our staff.

Peter’s breadth of knowledge and wisdom allows him to effectively diagnose the needs of plants. Sometimes just by walking into a garden he can create a prescription that fixes even the hardest issue. He is our Staff Botanist, Diagnostician, and all around Mentor. Recently, he has put his immense knowledge and skills into developing a new department that focuses on Plant Healthcare. As he puts it, “Magic through Science”. The PHC staff that surround him have avidly consumed his teachings. Substantially developing their own plant wisdom, many have taken on difficult plant health issues with spectacular results.

Plant Healthcare has been an instant success with customers! The proper treatment of insects and diseases including Organic methods has made pest control a necessity for every plant. Correcting hormonal imbalances caused by planting in containers or refurbishing soils leached of nutrients by irrigation systems are big challenges PHC has become quite comfortable addressing. The scientific approach to the complex demands of keeping plants healthy in our harsh city environment has made many a customer say WOW!

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