Providing education regarding site landscaping and offering clients an opportunity to ask questions is very important to us. Botanicon is here to support you in managing one of the largest line items on a communities budget, the landscaped environment.
Our independent, third party landscape vendor management, horticultural consultation and quality assurance services benefit plants and people. We facilitate all aspects of site landscaping on behalf of our clients, and sharing knowledge helps us all do our jobs better.
In June, we hosted our 1st educational event HORT 101: Landscape Plants for Southern California Landscapes at the Water Conservation Garden. Attendees were led on a tour throughout the garden to view and discuss low maintenance, water conscious plants. They loved it and asked for more!
The tour was outstanding. Excellent information!
Great tour! I’d love to learn more about focused areas in the landscape – islands, slopes, entrances.
Knowledgeable speakers. How about more on best practices for HOA Boards and Landscapes?
Well, here you go! Our 2nd Landscape Seminar, HORT 102 is being held on Friday, Oct. 4, 2019 11am-4pm. We will host property managers, HOA board and landscape committee members, developer and municipal land managers for an afternoon of education and opportunity. Location TBD, but somewhere in Central San Diego. So, save the date!
Topics? Attendees decide! What horticulture, landscape, tree or irrigation topics would benefit your community? Email or call us to be added to our interest list, and choose from some topics below or write in some of your own.
3 Items for Visual Inspections of Landscape Irrigation
Landscape water use is a big concern here in Southern California. It is a very hot topic with many facets. Water costs a lot of money here, and without oversight, can be a source of complaints, liability and cost over-runs for Homeowner Associations, site users and communities. Landscape managers must be experts at proactive water management! We need to spot coverage issues before they become problems. We identify plant stress from too little water, sometimes from far away at 25 mph! We must also quickly identify over-watering signs like certain weed species growing, erosion or algae.
Irrigation systems should be turned on regularly by to check for issues. This should be in your landscape maintenance contract. Many of the small repairs are within the scope of the on-site contractors agreement, others require an extra work proposal. What does your communities landscape maintenance contract say with regards to irrigation? How specific is the language?
Because July is Smart Irrigation Month, here are some things we look for when conducting site irrigation inspections.
Controller – programmed correctly, battery functional, map and written schedule present, each station operates electrically, signs of animal intrusion in housing
Valves – check for leakage, seepage, signs of animal intrusion in boxes, watertight connectors and solenoid connections functional
Wiring – broken wires, corrosion
Sensors – operational and correctly wired
Backflow prevention – check for leakage, note inspection date
Pressure regulator – operational and set to correct psi
Plantings & hydrozones
Plantings – symptoms of drought or over-watering, water hitting trunks and pooling, sprinklers blocked by large plants
Soil – excessive thatch in turf, mulch needed, soil type and infiltration
Hydrozones – exposure correct for zone, plantings in groups of like water requirements according to station
Lateral line components
Pipes – signs of breaks or leakage
Heads – correct spacing, same head on each valve, sunken heads, tilted heads, low head drainage
Drip – filters cleaned, pressure correct, even water distribution, clogged emitters
We hope this helps your community manage its water resources and protect the investment you have made in site irrigation. In all my years in the landscape industry, I can say that irrigation issues are the number one cause of landscape plant problems. Protecting landscape assets for stakeholders is what we specialize in. Need an irrigation inspection? Contact us!
I’ll be teaching OH 170 Plant Materials: Trees and Shrubs again Fall Semester at Cuyamaca College. Class starts August 21. We will be having some of our class meetings at Balboa Park, the best place in San Diego to learn about woody plants!
A couple weeks ago Botanicon led a tour of the Water Conservation Garden in El Cajon, CA. Our focus was educating HOA Board members and Property Managers on low maintenance, water wise plant choices for their communities. And who doesn’t like to get outside and look at beautiful plant specimens? Thank you to all who attended and sponsored our event.
All landscapes have plant health issues which arise. A question I am often asked is what is going on and how do I fix it? Some landscape plant health concerns are easy to identify, an aphid infestation for example. Often times issues have more than one causal agent. Abiotic factors many times will lead to biotic issues. Right plant, right place is applicable here.
An abiotic factor is a causal agent which is non-living, such as watering, soil conditions, chemical use, aeration, mechanical damage, etc. Biotic causal agents are living organisms, such as whiteflies, oak root rot, bacterial leaf scorch.
In order to fix the plant problem, it is critical to have an accurate diagnosis. Just like a medical doctor would do during a patient visit, many questions need to be asked and answered for us to be confident about what is going on. Ineffective treatments arise from inaccurate diagnoses.
Because plants and trees can not tell us what is going on, like a medical patient would, we need to ask lots of questions and look for answers to determine a diagnosis. What are the symptoms? A symptom is the plants reaction to a causal agent – stunting, chlorosis, spots, tissue death. Are there signs? Signs are a physical presence of a pest – excrement, casings, mushrooms, frass.
Questions about the plants location, species susceptibility, care, environment, irrigation, planting methods, etc. need to be answered. We are investigators looking for clues to point us towards a diagnosis. Then a treatment plan can be formulated.
Using a systematic, methodical, question based approach is the only way to approach diagnosing landscape plant problems with confidence. Here is a slide show I presented at a recent seminar which outlines the process. Need a consultation and diagnosis? Just ask us!
Tired of seeing the same trees being used over and over again? Tree species diversity is important to the urban forest, so let’s mix up the planting palette. Chionanthus retusus, or Chinese fringe tree, is blooming here in San Diego, and what a show! I took these photos about a week ago when I hit the brakes at the sight of these blooms.
This tree is useful in the landscape because of it’s small size at maturity, less than 25′. Although it is not drought tolerant, it is useful for patios, lawn and garden settings. It’s striking show of fragrant white flowers in spring-summer is followed by yellow fall color and small red berries which attract birds. Chinese fringe tree grows in clay to loam soils in full sun or part afternoon shade in warmer areas. Another tree I love to see growing and being planted!
SelecTree. “Chionanthus retusus Tree Record.” 1995-2019. May 14, 2019. < https://selectree.calpoly.edu/tree-detail/chionanthus-retusus >
University of California Agriculture and Natural Resources is hosting the IPM Training for Landscape Professionals on May 23, 2019. Location is the Scottish Rite Event Center 1895 Camino del Rio South, San Diego, CA 92108.
Topics of interest for pest management in the landscape setting and CEU’s available. I’ll be speaking on the topic of Diagnosing Landscape Plant Problems, and highlighting the steps and resources useful for an accurate diagnosis.
People love lush landscapes and instant gratification. Clients of landscaped sites want that full garden look from day one. Property owners, contractors and landscape architects achieve this by densely populating the ground with plant material, regardless of species size at maturity. It sells and leases properties, plain and simple.
But what are the long term costs? And is this sustainable? When asked to review site planting plans or conduct turnover inspections, we regularly advise clients to reduce planting density or remove plants which are already in the ground. Gasp!!!
Maintenance: Costs of constantly pruning plants to contain their size at maturity is a waste of resources. Over-planted sites require multiple pruning visits each year, even forcing contractors to use the dreaded hedge trimmer where it does not belong.
2. Water: Plants compete for water resources. An over-planted site requires more water, much of it wasted by plants blocking the sprinklers.
3. Soil: Plant roots compete for soil space. More roots, less soil, more water use, more fertilizer use.
4. Waste: Clippings from pruned plants must be raked up, removed and hauled away, as most large landscapes do not have their own composting operation on site (we wish they did). Labor and fuel resources are wasted, even if the eventual destination is a municipal compost facility.
The long term costs for maintenance, water and waste removal get passed along to the end user – the property owner, municipality or community.
Comparison of planting densities and maintenance costs over timefor the Miscanthus sinensis (silver grass) planted in late 2013
MAINT. FOR 10 YR
AS PLANTED W/ 5-GAL PLANT
40% LESS DENSITY 5-GAL PLANT
40% LESS DENSITY 1-GAL PLANT
250 ea. of species planted from 5-gallon stock
Cost per 5-gallon plant installed $35
Cost per 1-gallon plant installed $14
Time per plant to cut to the ground, clean up, and haul debris once per year: 5 minutes/5-gallon plant
Time per plant to cut to the ground, clean up, and haul debris once per year: 3.5 minutes/1-gallon plant
Maintenance labor rate per hour: $25
As you can see, costs over time for a less densely planted site using smaller container sizes saves money and resources. The costs indicated are for maintenance alone, not including water wasted, plants dying for lack of irrigation coverage or root competition, composting, etc. Many plants actually establish and grow better when a smaller container size is used at planting.
An aesthetically appealing, resource friendly landscape is within reach if we formulate planting plans and densities with species selection, growth rate and size at maturity as the main driving force. This is a more sustainable landscape approach. Properties will still sell and lease if done thoughtfully.
When conducting landscape inspections, I commonly see all of these offending practices in regards to trees….poor quality nursery stock, planted too deeply, soil is amended instead of proper species selection, holes dug too large, tree “snorkels” installed, staked improperly and left on too long, hardscape and infrastructure interference, root barriers, the list goes on. None of this has a basis in horticulture or promotes healthy tree establishment and growth. Let’s stop this and promote quality in the landscape so these site assets reach all of their potential for decades to come.
Ok. I admit this blog is going to turn into a rant pretty quick because there seems to be a lot of ways to screw up a fairly simple horticultural practice—tree planting. Since Arbor days are happening/happened everywhere around now, its a good time to talk about how to plant trees. First let me state some simple and useful guidelines for a successful tree planting.
-When at all possible, plant trees bare-root. Even washing the container media away. This allows for inspection and removal of root defects. -Select trees carefully that are free of defect and disease and that are adapted to your climate and soils -Plant the youngest tree you can -Take care in choosing the planting site. -Avoid Root Barriers -Plant trees so that the root flare is above ground slightly -Plant trees in a hole only deep enough to contain the root system, no double digging. -Plant trees in a hole wide enough to contain the root system, no wide holes (unless there is a reason for using one) -Fill the hole with soil removed to make it. Do not amend the backfill around newly planted trees—Do not put rocks in the bottom of a planting hole! -Plant trees without staking unless there is a reason to stake them -Plant trees away from turfgrass or other groundcovers. -Plant trees under the cover of a fresh layer of arborist chips.
-Irrigate newly planted trees from the surface—Do not install U tubes or tree snorkels to irrigate deeply.
I guess this rant comes from the variety of tree planting specifications I have seen over the years used by municipalities, landscape architects, nurseries and others. There seems to be a need to use the latest product, method or modification to site soils in order to make a fancy planting detail. Simpler is better and research by Universities has not verified most of the “innovative” approaches seen in planting details.
The first step in planting a tree is to chose the tree you want to plant. While this seems simple there is a lot that goes into tree selection. Setting aside personal choices, it comes down to selecting a tree that is healthy and free of defect. The potential candidate tree should have no signs or symptoms of disease, a naturally developed canopy unfettered by nursery pruning (especially heading cuts), and has few or no root defects. Initial superficial examination of the root collar in the nursery can eliminate some trees with circling or girdling roots. However, when the tree is planted root washing will reveal the entire root system and as Dr. Linda Chalker Scott has shown in this forum, root washing allows for rapid establishment in site soil. When at all possible chose the youngest tree you can for the new site. Young trees have fewer root defects, and we have the advantage of training them (structural pruning) from an early age. Young trees establish rapidly and will often outgrow older, boxed trees. The larger the specimen that you plant, the more chance for establishment problems such as settling, drying out, root rot or just slow growth. Planting trees from seed is ideal but most gardeners don’t have the patience to wait and seedlings, and seedlings do not give the option of using cultivated varieties that impart horticultural value, such as predetermined flower color, disease resistance, and known form (canopy shape and size).
Once the tree is selected, purchased and root washed, it is time for setting it in the ground. The first step is choosing a good planting site. A good site for a tree is somewhere that provides adequate soil volume for its roots to expand and for its canopy to expand. Many trees in urban settings fail to achieve their potential because they have restricted spaces to grow in. Chose a location in full sun. Unless you are planting a species that grows well in shade or needs protection from the environment, most trees will grow best in a sunny location. While trees are forgiving of most soil conditions, they will not grow well in compacted soils. If this is all that is available, break up compacted soils before planting. Consider the ultimate size of the tree you are planting, and imagine it attaining that size in your planting site. Avoid sites that have close proximity to buildings or hardscape. One of the most frequent problems with trees is that as they attain mature size they conflict with the infrastructure at the site.
Dig the hole for your tree so that the roots are very slightly above the grade. Do not double dig! While double digging has its proponents, there is no research-based reason for destroying soil structure– it is a disaster for tree planting. When a hole is dug too deeply soil will always settle after planting and irrigation resulting in the tree being planted too low in the ground. The root collar is buried and this is a predisposing factor for disease. The hole should have undisturbed soil under the roots. The hole only needs to be as wide as the root system. While many planting details show wide holes these are not necessary in most garden sites. If the site is compacted, wide holes can give temporary advantage to a newly planted tree, but the width of the hole will be the size of the “pot” the tree will have to grow in. So it is better to modify the site first to take care of compaction and then you will not need a wide hole.
Root barriers were very popular and are still specified today. They actually do not usually achieve thier goal of preventing surface roots and protecting infrastructure. Trees outgrow root barriers and they result in increases of landscape trash/pollution. Root barriers can also create root defects such as circling and girdling roots. Do not install root barriers, if you are tempted to do so you are likely not choosing a good site to plant a tree.
Cover the roots with backfill from the hole. Do not modify the backfill. Research does not support adding amendments to planting holes for trees. The native soil is what the tree will be growing in ultimately, and there is no reason to modify it. If the soil at your site is so bad that it needs to be changed, this should be a site-wide soil modification that will cover all the area the tree roots will explore up to its maturity. Most gardeners are not able to do this. Roots rapidly expand beyond the planting hole within months, so the time and benefit derived from an amended planting pit is minimal. Adding amendment, especially organic amendments to backfill can also be disastrous for trees. The organic material may utilize nitrogen in the soil and lead to a deficiency in the newly planted tree, worse, it may break down and cause anaerobic conditions in the bottom of the planting pit. Avoid amending planting holes! Never place rocks in the bottom of the hole—this does not create drainage, but creates an interface that prevents it.
If you have selected a good tree, it will stand without staking. There are three reasons for staking: support; anchorage; and protection. Support is sometimes necessary when a tree is cultivated with a long un-tapered trunk and a lollipop crown. Lollipop trees are often sold in nurseries as they resemble small trees. Trees trained in this manner, will not stand without staking. Loose staking allowing trunk movement will foster development of caliper so the tree can eventually stand without supportive staking. Anchor staking is used for trees that experience high winds and “staked out” with guy wires and a non-constrictive collar. Protective staking is analogous to placing bollards around a tree prevent impact from machinery or cars. Always remove the nursery stake at the time of planting and provide any additional support the tree may need. Many Cooperative Extension services have publications on how to stake a shade tree.
Avoid planting trees in lawns. Turfgrass and trees conflict with each other. Trees shade turfgrass which results in a thinning sward and increased disease prevalence. Turfgrass slows the growth of trees in an attempt to limit their shading effects. Turfgrass is a very competitive water user and trees will be deprived of moisture and nutrients if turfgrass is present. If trees must be planted in lawns, maintain at least a 1 yard radius around them with no turfgrass.
It has become a common practice to add irrigation or aeration devices to tree plantings. Sometimes called a tree snorkel these plastic 4 inch U tubes are buried below the root zone. Kits can be purchased from Box stores, and architectural details have been drawn specifying their use. Work by UC researchers showed that oxygen does not diffuse far from aeration tubes. So utilizing tree tubes to increase air flow is suspicious. Some planting details specify adding irrigation to the tubes to force a deep rooted condition in the tree. This places water below the root system, which can dry out and compromise establishment—not a good idea… Worse of all tree snorkels are sometimes installed with no purpose at all other than that was what the planting plan indicated. This is a needless practice and results in landscape pollution. Long term, tree snorkels are ugly, easily broken and provide no useful function to an establishing landscape tree. It is not in the nature of trees to proliferate absorbing roots deep in soil and snorkels will not change a tree’s genetics.
After the tree is set in its hole, and backfill settled in with water, apply a 4 inch layer of arborist chips as far out from the trunk as feasible—at least several feet. The chips will modify the soil improving, chemical, physical and biological properties while conserving moisture from evaporation, preventing runoff, and germination of annual weeds. Generally trees thrive under mulch as it simulates litterfall, or accumulation of organic matter under their canopies. Replenish the mulch as it deteriorates. Finally apply irrigation as needed through the mulch from the surface of the soil. This will help establishing roots, leach salts, and move mulch nutrients into the soil profile. Avoid companion plantings near the main stem of the tree and avoid piling mulch around the tree stem. Following these guidelines will lead to a healthy and useful shade tree that provides its many services for decades.
Dr. Downer has 34 years of experience as a horticulture and plant pathology Advisor with the University of California Cooperative Extension in Ventura County. Dr. Downer’s academic training is from California Polytechnic Univ., Pomona, (BSc. horticulture & botany, 1981; MSc. Biology, 1983;. In 1998 he earned a Ph.D. in plant pathology, from University of California, Riverside. Dr. Downer’s research is focused on mulch, soil microbiology and disease suppression in mulched soils, diseases of shade trees and cultural practices to maintain landscape plants. Dr. Downer is a member of the American Society of Horticultural Science, the American Phytopathological Society, The International Soc. of Arboriculture, and the Western Chapter of the ISA, and the International Society for Horticultural Science. Dr. Downer is an Adjunct professor at California Polytechnic University in Pomona. Dr. Downer serves on the Board of the John Britton Fund for tree Research as the chair of the research advisory committee, and currently chairs the regional conference committee for WCISA. Dr. Downer has a love of shade trees, Shinrin roku (forest bathing/walking) tree work, wood working, horses, gardening, horticulture and the study of plants and their biology.