2.Selection of Plants



Chapter – 4

Selection of Plant Material for Landscape

(Sudhir Kamal Seem, M. Arch. (Landscape), Senior Architect, CPWD)

The success of landscape design with plants depends on how to choose the appropriate plants for a particular situation. Thoughtful selection of the trees, shrubs, climbers, bulbs, foliage plants, grass, groundcover and aquatic plants transform the barren landscape into meaningful landscape. Efforts should be made to select an appropriate plant material for the given situation based on the following criteria :

(i)    Habit               

(ii)  Colour             

(iii) Season of flowering

(iv)  Form              

(v)  Rate of growth and Environmental considerations.

1. Trees:The selection of trees should be based on season, size, form, situational preferences of surroundings and artifacts.

1.1 Flower Colour

White : Alstonia scholaris, Baiiasea minor, Magnolia pterocarpa Milingtonia horternsis and plumeria acurmnaata.

Yellow  : Cassia fistula, Bauhinia tomentosa, Saraca indica, Peltophorum pterocarpum and Tabebuia spectabilis.

Red : Bombax ceiba, Amberstia nobilis, Cassia marginata

Scarlet : Barningtonia monandra, Cassia pavarnica Crennigena, Kelnbovia hospita.

Purple : Lagerstroemia speciosa, Bauhinia purpurea, Melia azadirach, Pachira, rosea and Tabebuia rosea.

Orange, Red, Crimson, Scarlet : Butea monosperma, Colvia racemosa and spathpdea campanulata.

Blue, Mauve, Violet : Jacarpanda aquisatifolia, Guaicum officinale, Millenia avaliolia and Solanum grandugkirum

Greenish Yellow : Monodora grandiflora.Casealpnia,

Creamy White or Yellow : Michelia champaca, Madhuca Indica, Magnolia grandiflora, and Terminalia Arjuna.

1.2 Season of blooming

Ever blooming : Callisetermon lanceolatus, Mimusops elengi, Plumenia acuminata and Thespesia populnea.

Winter blooming : Bauhinia purpurea, Butea monrosperama. Monodora grandiflora

Spring blooming : Tabebuia, Amheristia niobilis, Bombax ceiba, Jacaranda, Saraca indica, Spathodea

Summer Blooming : Erithrina indica, Cassia, Jacaranda, Lagerstroemia spp.

Rainy season Blooming : Plumeria alba, Anthocephelus cadamba, Barringtonia raccemosa, Casia Marginata, P. rubra, Covillea raccemosa.

1.3 Range of Tree sizes

Dwarf trees (3 to 5m tall) : Albizia lebbek, Bisantha, Bixca orellana, Brownera grande eps, Crodia sebestena. Wevthrnia blackein Parkinsonia acuminata, Plumeria rubra.

Medium size (6 to 10m tall) : Caesalpinia, Lagerstromia throreli, Melia azadirach, Plumeria accmnata, Saraca Inidica, Tabeulia spectabilis.

Tall tress (more than110 m tall) : Peltophorum roxburghii, Bombax malabaricum, Cassia monisia, Chorisia speciosa, Jacaranda, Millingtonia hortensis, and spatholea campanulata.

Giant trees : Ficus bengalensis, Bombax ceiba, Colvillea racemosa,

1.4 Growth Habit of Trees

Oval : These plants are suitable for frame or screen. Populus alba, Albizzia julibrissin, Crataeqs cerusoalli Cornus sp., Betula pendula Cassia fistula

Vase shaped : They can be used above the large shrubs or small trees. Melia azadirach, Plumeria acutifolia. P.alba. P.obtusa, Saraca Indica. Almus Americana.

Pyramidal : It can be used as an accent plant. Pinus roxburghii, Araucaria cooki. Thuja compacta, Quercus palustris, Stercula foedtida, Polyalthia longifolia.

Round : These plants can be used in the lawn as specimen. Plumeria alba,Chorisia speciosa Mimusops elengi. Morus rubra, Quercus.

Columnar : They frame the views and structure in the landscape setting. Juniperus chinensis, Betula pendula, Quercus robustaj Eucalyptus robusta, polyelthia pendula.

Weeping : It can be used as a focal point. Salix Babylonica, S. alba. Putranjiva roxburghii, callistemon lanceolatus Tecomelia.

Round to spreading : These plants mass well to create grove effect. Dalbergia sisso, Dillenia Indica, Ficus glomerata, Thespesia populnea.

Fan shaped : They can be used as a focal point. Cycus revoluta, Borassus fladellifer, Oredoxa regia.

1.5 Trees with scented flowers : Anthocephilus cadamba, Alstonia scholaris, Cananqium odoratum Michelia champaca, Mimusops elengi, Dillenia indica, Gardenia latifolia, Custravia augusta, Magnolia grandiflora, Nyctanthes arbortristis.

1.6 Wind Resistant trees : Eugenia jambolana, Caesalpinia pulcharima, Peltophorum pterocarpum.

1.7 Salt Resistant trees : Azadirachta Indica, Acacia sp., Butea monosperma, Azadirachta. Indica, Bassia Latifolia, Eucalyptus citriodora, Phonix dactylofera and Phyllanthus emblica.

1.8 Drought Resistant : Butea monosperm, Acacia sp., Albizzia lebbek. Casuaria equisetifolia. Crataeva religiosa. Tecomelia.

1.9 Wet Land trees : Nyctanthes arbortristis, Dillenia Indica, Michelia champaca, Saraca Indica, Thespesia populnea, Salyx Babylonica, Ecualyptus eostata, Guaicum officinalis.

1.10 Fast Growing Trees : Pongamia glabra, Sesbania grandiflora, Cananqium odoratum, Erithrina Indica, Thespesia populnnea, Populus sp., Salix sp,. Euclyptus sp., Thuja compacta.

1.11.Shade givers : Pteropsperum acerifolium, Albizzia lebbek, Pelptophorum, Michelia champaca, Anthocephalus cadamba, Dalbergia sisso,. Glyricidia Maculata accer sp., Cornus florida.

1.12. Trees tolerant to Dust and Smoke : Acacia auriculiformis, Alstonia soholaris, Butea monosperma, Ficus Benjamina, F. benghalensis, Madhuca Indica, Pongamia glabra, Ficus religiosa, Terminalia Arjuna, Albizzia llebbek, Bombax ceiba.

1.13. Trees for Noise Reduction : Terminalia Arjuna, Alstonia scholaris, Azadirachta Indica, Butea Monosperma, Mangifer Indica, Madhuca Indica, Juniperus chinesis, Eucalyptus Citradora, Kigelia pinnata

Chapter – 5

Plants and Indoor Air Quality

(P.S.Sodhi, M. Arch. (Landscape), Architect, CPWD)

Indoor Air quality plays an important role in the work performance and the health of the users. With the passage of time the indoor levels of pollutants increases, sometimes much higher than the outdoor levels. To mitigate these effects a study was undertaken by IIT, TERI and learning’s from NASA that there are number of common green plants, with which we can grow all the fresh air we need indoors to keep us healthy. Common indoor plants may provide a valuable weapon in the fight against rising levels of indoor air pollution & are very useful in absorbing potentially harmful gases and cleaning the air inside modern buildings and provide a natural way of helping combat “Sick building syndrome”.

The most common three air quality improving plants are Areca palm, Mother-in-Law’s Tongue and Money Plant.

Areca palm is a plant which removes CO2 and converts it into oxygen. We need four shoulder-high plants per person, and in terms of plant care, we need to wipe the leaves every day in Delhi.

Mother-in-law’s Tongue is again a common plant. We call it a bedroom plant, because it converts CO2 into oxygen at night. One requires about 6-8 such waist high plants per person in the bedroom.

Money plant is a very common plant; preferably grows in hyrdoponics. It is excellent plant for removing Formaldehyde and other VOC’s (volatile chemicals) in the air.

The indoor plants most effective in removing Formaldehyde, Benzene and Carbon Monoxide from the air are:

1 Bamboo Palm   -   Chamaedorea Seifritzii
2 Chinese Evergreen - Aglaonema Modestum
3 English Ivy - Hedera helix
4 Gerbera Daisy - Gerbera Jamesonii
5 Janet Craig - Dracaena “Janet Craig”
6 Marginata - Dracaena Marginata
7 Mass cane/Corn Plant - Dracaena Massangeana
8 Mother-in-Law’s Tongue - Sansevieria Laurentii
9 Pot Mum - Chrysanthemum morifolium
10 Peace Lily - Spathiphyllum
11 Warneckii - Dracaena “Warneckii”

All the above mentioned indoor plants can be used to improve the indoor air quality.

Chapter- 6

Process of Planting and Transplanting of Trees

(Sudhir Kamal Seem, M. Arch. (Landscape), Senior Architect, CPWD)

Planting:Definition

Planting is the operation of transferring young plant from nursery to their permanent place in landscape.

Steps Involved in Planting: Site Condition

The conditions of the planting site are as important as the plant. Soil type and drainage, available water and sunlight, exposure to dying winds, and other factors must be considered.

Attempting to match the requirements of the plant to the site increase the survivability, performance, and longevity of the plant selected.

Soil Texture

The first step in assessing the condition of the planting site is to examine the soil. Whether the soil is sandy and well drained, or is it moist with some organic material, or is it heavy dlay and therefore, wet and perhaps compacted.

Construction practices such as cutting and filling, installation of underground utilities, and backfilling against foundations can create great diversity in soil structure. This variability can change drastically with depth and between planting locations on the same property-investigate each planting site.

Soil texture and drainage are closely related. Sandy soils usually are very well drained, have large pore spaces, and poor water- holding capabilities. They are usually associated with dry conditions.

Conversely, clayed soils have much smaller pore spaces, are poorly drained, and can suffocate plant roots. The pore spaces in soil are very important to plant growth because the oxygen that occupies them is essential to healthy roots. A tree planted in poorly drained soil will be slow to establish, lack vigor, and often will slowly die.

Drainage

Because plant roots require both moisture and oxygen for growth, soil drainage should be checked before planting. A poorly drained soil, high in moisture but low in oxygen, prevents both proper root development and growth of beneficial soil micro-organisms that are responsible for decomposing organic matter and releasing plant nutrients.

To test for soil drainage, dig a hole 18 inches deep, fill it with water, and let it stand overnight. If the water has not drained by morning, there is a draining problem. (Do not leave the drainage in this matter after heavy rainfall or before the ground has thawed in the spring).

If soil drainage is inadequate, species that are tolerant of poorly drained soils may be planted, or soil drainage may be improved. This can be done in two ways. If a hard pan is present (a compacted, impermeable layer of soil) with an underlying layer of well – drained soil, a hole can be dug down to the permeable layer to provide drainage for the planting hole.

If the soil is poorly drained and there is no well-drained layer below, a tile system can be laid. However, this is expensive and requires the assistance of a professional for proper design. Simply adding gravel to the bottom of the planting hole will further decrease oxygen availability to the root system.

Compaction of the soil by vehicles or people can reduce pore space and restrict water infiltration, as well as cause physical damage to roots of existing trees. In compacted soil, oxygen is depleted, carbon dioxide accumulates, and root penetration is reduced. This is detrimental to root growth. Aerating the soil will help correct the problem.

Soil pH is a measure of the acidity or alkalinity of a soil. A pH below 7 (7 is neutral) would indicate an acidic soil, and a pH above 7 indicates an alkaline soil. Many plants have an optimal range of pH. Most trees thrive on a pH between 5.5 and 6.5. Soil pH is raised by calcium carbonate or lime. Plant species that will tolerate a high pH should be considered for areas with buried concrete, near foundations, or sidewalks etc.

Before a plant is planted on a particular site, a soil test should be conducted to determine possible pH problems or nutrient deficiencies.

Water

The correct amount of water for plants is essential. Selected plants that are tolerant of excess water for low areas where water may be standing or very close to the surface, or where a heavy clay soil exists. Standing water or a high water table means low oxygen content in the soil. Therefore, trees and shrubs that can tolerate excessive moisture are often better suited to these poor sites.

Sunlight

Although some plants can tolerate low light conditions, most require full sun to maintain their vigor and attain their full potential. Some plants may require some protective shade to prevent leaf scorch and desiccation.

Location

The location of the planting site in relation to other trees and objects such as buildings, fences, etc. will have a considerable influence on temperature and moisture conditions around the tree. Prevailing westerly winds have a drying effect on non-protected sites. The south side of a building will be much warmer and drier than the north side. The warming effect of the sun on a cold winter day can cause injury to the bark and may cause the tree trunk to split. For evergreens, this warming can cause water loss and growth activity resulting in needle damage when the temperature is again lowered Plant hardiness can be greatly affected by the amount of protection provided by individual microclimates.

Planting Season

The season for planting will depend upon the following factors:

1. Adequate amount of rainfall.

2. Presence of moisture in the air.

  • Mass planting should never be done in summer. A local level planting can be done in summer, provided proper irrigation is available.
  • Plants growing in areas having composite climate should be shifted to the new site prior to the monsoon, preferably in the month of July in northern parts of India.
  • When there is doubt of water logging, planting should be carried out at the end of rainy season.
  • Salix babylonica, Salix monosperma, Dalbergia sissoo, Calestamon lanceolatus, Terminalia arjuna etc. can be planted in waterlogged area.
  • In Punjab, planting is done in February when dormancy stage is crossed.
  • Roses must be planted in the beginning of winter i.e. September.
  • General planting should be carried out between February and April. March is comfortable for plants as temperature is neither of the two extremes and the soil temperature during this period is steady with adequate moisture content.

Planting Procedure:

Preparation of Pit:

  • Pit should be prepared two months prior to planting to help the soil expose to the scorching sun.
  • Tree pit should be 1.2mX1.2mX1.2m. The pit should be properly dug as per specification. Poor digging with improper base dimension would lead to the undernourished rowth of the plant.
  • While excavating, remove the top soil to a depth of 6" to 9" and keep it aside. Topsoil undergoes change in fertility status in the span of two months (between December and February)
  • If the subsoil is poor in terms of water holding capacity etc., it must be treated with 3 parts of manure + 2 parts of sweet earth + 1 part of sand(3:2:1). This will improve the drainage conditions and also enhance the acquired fertility of the soil.
  • Manure might generate heat after water is added. Hence, precaution must be taken to protect the plants. Also one third of compost manure is added at the time of refilling.
  • After refilling, soil is consolidated by watering. Soil should be allowed to get dried up by exposing it to the sun.

Planting the sapling

  • Prior to planting of the sapling, there is a need for the introduced sapling to get acclimatized to the new environment. If possible such saplings should first be procured in nursery beds.
  • Preparation of hole: Hole is prepared in the soil large enough to take the roots of the sapling with a layer of sand underneath.
  • Wrapping of roots: The roots of the sapling when lifted from nursery are wrapped with good earth, such that the evapo-transpiration is checked and the moisture content is maintained.
  • Damaged roots and shoots are to be cut off to prevent evapo-transpiration from shoots and roots.

Staking

  • Staking is done to protect the tree from bending and toppling due to the wind pressure. The staking thus helps in helping the tree sapling to hold vertically and achieve the desired form.
  • The hole is then filled up with fine soil and firmly pressed down so that the roots are exposed. The soil is then consolidated property to avoid unnecessary settling or exposing of the roots.

Watering

  • Watering must be done every third day for a young plant sapling to survive. The site can be divided into three zones and each zone can be watered one day. Watering done should be copious.
  • Surface soil should be cultivated regularly to open up the soil so that proper aeration of the soil takes place.
  • When subsoil drainage is poor, due to presence of clay or clay pan, it will result in damage of the roots. Hence brickbats with stone cover and dry leaves are laid in the pit to a depth of 4" to 8"
  • White ants may occur if manure quantity is high. Hence, it is necessary to keep the manure quantity to the minimum.

Planting of Shrubs

  • There are two ways of shrubs plantation, either individual or group planting.
  • For individual plantation, the distance from centre to centre is usually 0.6m X 0.6m X 0.6m, but can very as per the requirement of the type of shrub.
  • 6" of topsoil is removed and kept aside before trenching is carried out.
  • Trenching is to be carried out in the entire area taken by the shrub bed. The depth of trench is between 25cm to 40cmAll weeds and roots, stones etc. are removed. 
  • 10cm of well rotted sable manure should be supplied to the bed and spread and mixed with 30cm of soil.
  • The surface is to be roughly dressed and irrigated thoroughly. The soil is then firmly consolidated.
  • When subsoil drainage is poor, the soil in the pit is to be replaced with good soil with 10cm manure.

Transplanting: Definition

  • Transplanting is the process of bodily lifting of mature and large plants from their position to a new position.

Considerations for Transplanting

  • Before transplantation a woody plant, evaluate whether or not the tree or shrub is likely to be a successful transplant. Prune the crown of the tree to a third and roots to a minimum such that it can be transported Plants which are already in advanced stages of decline are especially likely to succumb to transplantation stress.
  • Often a young nursery-grown plant will resume growth sooner than an older transplanted tree or shrub and will provide more long-term benefits in the new planting location.
  • Shrubs have better transplant tolerance than trees, deciduous plants better than evergreens, shallow rooted species better than deep rooted species, and younger plants better than older plants.
  • When deciding whether or not to transplant a tree or shrub, or to start over with a young plant, the following considerations are necessary:
    1. Species transplantation tolerance,
    1. Condition of the plant,
    1. Season to transplant,
    1. New planting site conditions,
    1. The Equipment needed and
    1. Follow up care

Season of Transplanting

  • Transplanting is done when there is enough moisture in the soil. Hence, monsoon is the right time as there is enough moisture in the soil
  • Some species may survive transplanting any time during the year when the ground is not frozen, but woody plants are preferably moved in the spring after the ground thaws and before the buds on the tree or shrubs begin to swell.
  • They may also be moved in the fall after leaf drop but before the ground freezes. Fall planting should take place soon after leaf drop, providing time for new water absorbing roots to develop before the soil freezes.
  • Since evergreens are especially prone to winter browning if planting is delayed until shortly before the ground freezes in the fall, they should be moved late in the summer to early fall.
  • Wood plants that are transplanted in late spring and early summer, when shoot growth is at its peak, tend to show the greatest transplant injury.

Site Selection

  • There are great differences in the environmental requirements for each tree and shrub species. Only transplant a tree or shrub where light, moisture, soil pH, and wind exposure are appropriate for the particular species.
  • All plants require space for root and crown development; therefore, consider mature plant size when planting trees and shrubs.
  • Soil characteristics are often limiting factors for woody plant survival in a given area. Sometime the soil is inappropriate for tree growth and will require improved drainage or amendments before trees and /or shrubs are planted at the given location. A soil test should be completed in areas where soil quality is questionable.

Transplanting Procedure

  • Plant should be bodily lifted with as many roots as possible and taken to the new position immediately. Ball of earth surrounding the root should be also be lifted.
  • Cover the root ball with damp material which will retain moisture (burlap, peat moss, canvas, plastic, etc.) until planting.
  • Plastic should only be used in shaded areas for less than a day or heat injury and/ or root suffocation may occur.
  • When a tree or shrub is stored, it should be protected from direct sunlight, winds, and temperature extremes. If any woody plants cannot be planted for more than a week, their roots should be covered with a match or moist soil and the plants should be placed in a shades area.
  • In all cases root systems should be allowed to dry out. Dry roots can severely decrease the potential for transplant success.
  • Roots should not be injured. It must be cut so that the amount of water absorbed in the new site can be checked. There is a change in the environment, thus more amount of water might create problems.
  • If the earth breaks away from the root area, it must be smeared with clay, cowdung and water.
  • The entire plant is then placed within the pit and fine soil can be added. Finally good soil will cover up the root. The replanting is to be done to the same depth as was at the old location.
  • Broken limbs should be removed and leaf area to be removed and leaf area to be reduced to check evapo-transpiration. At the same time branches have to be cut back.

Staking:

Trees should be protected from bending due to wind by stakes. Stakes also help in transpiration of water.

  • Care should be taken that clay is not brought into the new site. Thus, roots should always be washed before replanting.
  • Transplanting is done when there is enough moisture in the soil. Hence, monsoon is the right time as enough moisture exists in the soil. September is the ideal month for carrying out the process of transplanting.
  • Cold, moist and cloudy weather is the best for transplanting. The evenings are better suited for the purpose as plants refresh themselves in cool night.
  • Soft-wooded plants are better transplanted than hardwood plants.

Watering

After transplanting, copious watering is done. Copious watering procedure has to be clearly mentioned.

Post Planting Care

Watering

  • Too much or too little water after transplanting is a major cause of tree or shrub loss. The site should be thoroughly watered immediately after planting.
  • Thereafter, the soil must be regularly monitored to prevent drying out.
  • If rainfall is inadequate, the soil around the plant’s roots should be deeply watered approximately every 10 -14 days.
  • If unsure if the soil is drying, dig down 3 to 4” next to the plant. Wet soil at that depth verifies watering is not needed at that time.

Mulch

  • Mulches help conserve moisture, moderate soil temperature and control weeds around trees and shrubs.
  • They are placed on the soil surface over the tree or shrub root system. Either organic or inorganic mulches may be used.
  • Organic mulches may be composed of bark or wood chips, straw, partially decomposed leaves or other materials.
  • They should be applied 3 to 4” deep. Maintain a 4 to 6“ mulch-free area adjacent to the woody stems.
  • Inorganic mulches include crushed rock, woven fabric, and other materials. Should plastic mulches may impede or prevent root development because they do not allow air or moisture to move into or out of the soil from above?
  • Occasionally, when soil is poorly drained, mulch should not be used.

Fertilizer

  • For the first few years, woody plants rarely need nutrients beyond those naturally occurring in the soil. No fertilizer or manure should be mixed with the fill soil, as this could cause root damage.
  • If transplants appear to need fertilizer during the first few years, a totally soluble complete fertilizer should be applied.

Pruning

  • Pruning may be required when transplanting trees or shrubs. The amount of pruning depends on the size of the root ball and plant canopy, health of the plant, and the species transplanted.
  • Insect infested stems or those infected with disease should be removed during transplanting.
  • Any broken stems should be removed as well.
  • Additional pruning of shrubs may be required to balance the leaf area with the reduced size of the root system, but further pruning of deciduous trees should be postponed for at least one year after transplanting.
  • Pruning of conifers should be limited to diseased, insect, and broken limbs. If additional pruning of conifers is necessary, it should be limited to one-year-old wood whenever possible.
  • Late season plantings may require additional pruning since the plants have less time to become established before winter than those planted earlier in the season.

Mechanical Support

  • Mechanical support for trees may be necessary when the tree is tall, slow to recover, heavily foliaged, or planted in a sandy site.
  • Most small trees and shrubs do not require staking or other support and will develop strong trunks faster if allowed to move freely with the wind.
  • For trees that do require mechanical support, staking may be used. Two stakes can be placed opposite of each other and the tree anchored to the stakes with a nonabrasive material, such as a soft, board, fabric strap.
  • Any support provided to a tree should be removed as soon as the tree can stand alone, usually after the first growing season. The sooner the support is removed, the faster the tree will become stronger.

Root ball sizes for Deciduous Trees: Small Trees:

Height
(up to 6 feet)
Minimum Diameter Ball Depth
2 feet 12 inches 9 inches
3 feet 14 inches 11 inches
4 feet 16 inches 12 inches
5 feet 18 inches 14 inches

Root ball size for Deciduous Shrubs:

Height
(up to 6 feet)
Minimum Diameter Ball Depth
12 inches 9 inches 7 inches
18 inches 10 inches 8 inches
2 feet 12 inches 9 inches
3 feet 14 inches 11 inches
4 feet 16 inches 12 inches
5 feet 18 inches 14 inches
6 feet 20 inches 14 inches
7 feet 22 inches 15 inches

Root ball sizes for Evergreens Spreading, Semi-spreading and Globe (or dwarf) Types (broad leaf and marrow leaf):

Spread Minimum Diameter Ball Depth
9 inches 8 inches 6 inches
12 inches 10 inches 8 inches
18 inches 12 inches 9 inches
2 feet 14 inches 11 inches
21/2 feet 16 inches 12 inches
3 feet 18 inches 14 inches
31/2 feet 21 inches 14 inches
4 feet 24 inches 16 inches

Cone and Upright Types (broadleaf and narrow leaf):

Spread Minimum Diameter Ball Depth
18 inches 12 inches 9 inches
2 feet 14 inches 11 inches
3 feet 16 inches 12 inches
4 feet 20 inches 14 inches
5 feet 22 inches 15 inches
6 feet 24 inches 16 inches
7 feet 27 inches 18 inches

Columnar Types (narrow leaf):

Spread Minimum Diameter Ball Depth
12 inches 10 inches 8 inches
2 feet 13 inches 10 inches
3 feet 14 inches 11 inches
4 feet 16 inches 12 inches
5feet 18 inches 14 inches

References :

i. Study Material distributed at M.Arch. (Landscape) SPA, New Delhi.

ii. http://landscaping.about.com/ cs /shrubsbushes /ht /transplanting.htm

iii. http:// www.sustland.umn.edu /implement/ treespade.htm

iv. http:// www.lowes.com/ cd_Transplanting +Mature +Trees+ and+ Shrubs

v. American Standard for Nursery Stock

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