Less Trees Equal More Tornados

Prevent Tree Damage with Proper Pruning

Ok folks...after the latest tornado to spin through Dallas proper, it's time to talk urban heat island and preventative tree care. Unpruned, poorly and over-pruned trees are no match for 70-80 mile an hour winds. And you know this is only going to get worse, right?

With all the building going on in the DFW....more roads, more concrete, more roofs, more hardscape...we're only becoming a bigger heat sink. Without more greenscaping and tree canopy, the urban heat island problem continues to worsen. The hotter it gets here, the more extreme and frequent the intense weather events; such as destructive thunder storms, floods, and tornadoes. We've already witnessed that first hand the last few years.

To begin mitigating the heat sink issue here in DFW, we need to get another 250,000 trees planted. But with every major storm we have, we lose more tree canopy. After having lost power for a week, I'm now back at my house and checking out the neighborhood damage. As I walked my neighborhood and around White Rock Lake this morning, the extensive tree destruction all around us is so disheartening. And what's even worse, much of the tree damage and loss could have been prevented with good tree care and structural pruning.

But Professional Tree Pruning is too Expensive!

Neighbor's trees split in storm
PC: Leslie F. Halleck

Unfortunately, most homeowners just don't want to have their trees pruned. Or, they don't want to pay someone qualified to do it RIGHT. All those guys in trucks running around with ladders and chainsaws sticking tree pruning cards on your door? Sad to say, but most of those guys have no idea what they are doing when it comes to tree structure and physiology. Sure, they know how to use power tools, but that's about it. What they are doing is a huge amount of damage to your trees, which actually makes them significantly weaker and susceptible to damage in storms. And sure, they may be nice and you might like dealing with them. But that doesn't do you much good when your tree splits down the middle or falls on your house in the next storm.

A lot of the tree damage - and fallen trees - I see is also due to rot or disease that has gone unnoticed or undiagnosed because the trees have never been inspected by a professional.

So you can pay a little more upfront to have your trees cared for (and saved) by a professional who knows what they are doing - and have a healthier tree that's much more likely to be saved from storm damage; OR you can "save" a little up front with random landscape crews running around trying to get your tree business; but it will cost you a lot more on the back end when you have significant storm damage and or lose your tree/s altogether.

Large fallen tree showing large areas of internal decay
PC: Leslie F. Halleck

No More Broccoli Trees!

All those "broccoli trees" those guys are creating around town... you know, the ones that are heavily limbed up and all the inner branches are removed so you can get more sun to that scraggly patch of useless lawn? Yeah, those trees are far more susceptible to storm damage because all the canopy weight has been left at the very ends of the branches...weighing them down and increasing the chances they'll snap in a storm.

The term used more frequently in the industry for this type of bad pruning is "lion's tailing"

An example of lion's tail pruning, or a broccoli tree! This type of pruning is a recipe for disaster for your tree...and no small patch of lawn is worth it...

Texas Trees Foundation Urban Heat Island Study

Study Highlights

• Tree planting and preservation in Dallas can change the weather – producing cooler days and nights than will occur if tree canopy continues to be lost.

• The benefits of greening strategies can be as high as 15°F of cooling in some areas on hot summer days.

• Tree planting and preservation can save lives when implemented in concert with more reflective roofing and paving materials, with these combined strategies found to reduce the number of deaths from hot weather by more than 20%.

• Tree planting and preservation was found to be more than 3.5 times as effective in lowering temperatures as cool materials strategies.

• Dallas can achieve significant cooling and health benefits by planting 250,000 trees

Urban Heat Island Management Study, Dallas 2017

Personal Accountability & Responsibility

As a Certified Professional Horticulturist who has managed tons of landscapes and trees over the years, and worked along side with experienced arborists who know what they are doing, I'm begging you take better care of your established trees. Proper preventative pruning - that doesn't remove too much canopy and respects structural integrity and physiology of the tree - not only helps you keep strong valuable trees on your property but is also a more sustainable practice that helps increase our much needed urban tree canopy. In the face of intense climate change that's playing out before our eyes, it's the logical and responsible thing to do.

A big reason power was down so long in Dallas was due to vegetation down on lines. So the next time the power is down for a week due to mostly "vegetation" don't get mad at the city...don't get mad at the crews working hard to get it back up. How about as residents we focus on proper management of the trees on our own properties first? That means:

• Do not plant trees in city easements under power lines. Not only are you not supposed to do that in the first place, but most of you aren't having those trees properly pruned AND you're all screaming to high heaven when the power company has to send their contractors out to "butcher" them...if that's you, you probably shouldn't scream when your power is out because that tree lost branches and took down power lines. If you insist on planting trees in the easement, make sure their mature size is shorter than the power lines...that means NO LIVE OAKS. And know that if you do plant in a parkway/easement, you are responsible for maintaining the tree to code, even though it becomes the city's property.
  
  
• Have your trees inspected at least every 2-3 years by an experienced certified arborist, or certified professional horticulturist, and have preventative pruning performed to prevent damage. If you have a lot of large trees, I'd recommend scheduling an annual inspection. You may not need pruning that often, but other issues may be found in an inspection.
  
  
• If you have large trees on your property that are adjacent to lines, or are on your alley near lines, know the pruning code. You may have your own tree company prune tree growth that is 6-feet or farther away from power lines; they can also prune your trees near your house service drop line connection (you are responsible for pruning clearance around the service drop, not the city or powerline company). BUT you may not prune, or have your own company prune, tree growth that is within 6-feet of power lines. You must call the company that manages the power lines (such as Oncor) first to report pruning needs and they will send their contractors out to prune. Know that in this situation you don't get to decide HOW the tree is pruned. Whatever growth is encroaching on the lines will get pruned away...and yes, that might mean half the tree canopy and that's just how it us. Otherwise, those branches could take down your power lines.
  • Remember, the trees on your property are just that - your property. You are responsible for their care, not the city.
    
  • Remember, before you plant a tree, look up for power lines and call the “Call Before You Dig" toll-free line at 1-800-344-8377 to locate any buried power lines.
    
    
• Right Plant, Right Place....when planting new trees, know the mature size, both height and canopy (crown) width, of the tree species you're planting. If there are powerlines nearby, make sure the tree you're planting won't grow to impede them. We also need more species diversity in DFW, and most smaller urban lots won't accommodate live oaks so it's good to look at other tree species (not to mention live oaks can be seriously damaged in the severe extended freezes we get here in DFW every few years -and the consequences of such damage may not manifest until years later). Here is a list of trees and sizes from the City of Dallas.
  
  
• Tree Pruning Pick Up by the City: It's not the city's job to pick up all the trimmings or downed tree remains when you have tree work done. It's YOURS- that is part of the cost of tree pruning and removal. Good tree companies will chip and haul away all debris for composting. They will NOT dump it on your easement. Dallas has limitations on when and how much brush you can put out so be prepared for a citation and fee if you overload them with your entire tree.
  
  
  • Bulky Trash Pick Up Storm Schedule: This could take months folks, as it has in the past. Residents are being asked to HOLD any non-storm related bulky trash. Remember Dallas also has volume limitations now on bulky trash. You may get lucky and they'll pick up your excess without a fine this time, but don't count on it and don't get mad. We all have to pay for social services, which this is.

Some FAQs from the Dallas City Tree Code - Note maintenance requirements of the parkway adjacent property owner.

Property Rights: Who is responsible for pruning?

I'm adding this section into the original post due to some questions I received. Depending your your city code, this information may vary - but here in Texas, any tree growth hanging over your property line is yours to prune. I'd recommend you taking full responsibility for your trees and paying for all the pruning/care to be done by qualified professionals. But that means you need to have good open communication with your neighbor and work together to keep your trees healthy.

Question: "One thing you did not address is when to trim neighbors' trees hanging over one's house or property. Also, if the homeowner has a universal right to trim her own tree growing over the property line, does that extend to the arborist she hires? What happens if she hires an arborist and the neighbor threatens them away from trimming her trees which are growing onto his property? Etc.!"

My Answer: Legally anything hanging over your property line is yours to prune at your discretion (and vice versa for your neighbor), which can be problematic for the health of the tree if the neighbor who doesn't "own" the tree, applies extreme/poor pruning. I have large trees for which 50% of the canopy extends over my neighbor's property line and roof. Being a professional, I told them from the get go I needed to manage my own trees- I would pay for all the pruning, if they would let my crews onto their property to prune and clear their roof line. Yes, I have to bear the full cost for the pruning, but it's the only way to keep the trees healthy. I work with my neighbor to give them notice about when pruning crews will be coming and need access, and they let me know if they feel there are any issues. Legally, your neighbor doesn't have to let your arborist onto their property to prune what hangs over their property line - so it takes having good communication with your neighbor to negotiate that. But it is what's best for trees overall!

DFW Pros I can Recommend

This is not a sponsored post and I've spoken to no one about listing them here. Consider this a Public Service Announcement!

Dallas/Fort Worth: Personally, with my own trees (which have never had any storm damage), I've worked with Scott Dahlberg and his dedicated crews -first with Preservation Tree Services, and now Tree Tech. I've also worked professionally with Scott for many years with clients and properties I've managed. Preservation Tree was also my client for almost 10 years.

Other experienced and qualified companies I can personally recommend (in no particular order):

Sam Hill Tree Care

Arborilogical Services

SaveATree

Bartlett's Tree Experts

Texas Tree Surgeons

Davey Tree

Note: These tree care companies will likely be overrun with storm damage assistance requests - they will prioritize existing customers first so you may need to be patient. But once a customer you'll be able to get faster service in the future.

Interested in transitioning from plant passion to practice and profession?

Interested in transitioning from plant passion to practice and profession? Starting your own plant-based business, improving a green industry business you’ve already started, or are currently employed in the horticulture industry and want professional development and advancement opportunities?

Exciting news! I’ve just signed on the dotted line to create and teach two horticulture business courses through UCLAx. Both courses can be taken either in sequence or individually, depending on your needs. Each course will be 6-weeks, online and asynchronous (to be more flexible with your schedules) and with weekly live Zoom office hours with me as a group or scheduled one-on-one as needed. This week I’m starting to build the first course so please chime in if there are specifics you’d love to cover!

Course 1 (Fall ’24) “The Business of Horticulture” will introduce the green industry and its inner workings and the basics of starting and running business operations as they relate to the horticulture industry. We’ll cover some basics of financials, bidding and contracts, customer relations, sales, staffing, and marketing in the context of the horticulture industry. We’ll also work on an initial business plan project if you’re starting a new business.

Course 2 (Winter ’25): “The Business of Selling Plants” will focus on the basics of buying and selling plants (as a grower and reseller) and we will be covering legalities, how to manage live inventory, learn savvy buying and inventory skills, plant pricing, sales, and marketing.

These are of course just quick descriptions of each, and if you know me or have taken one of my courses, you know you’re going to get a lot of information and guidance.

Both courses will be interdisciplinary, meaning they are for those who aspire to work in or own their own business in the fields of garden design, garden center/plant shop retail, horticulturist, landscape maintenance, landscape architecture, plant growing, plant stylists, plantrepreneurs, arborists, and all allied trade. We can tailor conversations around everyone's individual disciplinary needs.

The courses are open enrollment: you don’t have to be a UCLA student, anyone, from anywhere, can enroll. You can take the courses for credit, pass/not pass, or not-recorded as simply continuing education. If you are a UCLA student, or are pursuing the Horticulture Certificate or Landscape Architecture Certificate in the UCLAx Horticulture program each 6-week course will be worth 2-credits. You can also hit your employer up for continuing education benefits!

Course 1 starts September 24, 2024 and ends Nov. 5th; registration opens July 29th.

More details to come, as well as course links, as I get further into development, and we get the course descriptions and syllabus up online. I’ll post links once we get to that point, but please feel to contact me with questions.

You know, the Zone 5 Mafia right? You gotta watch out for ‘em! Look, I say this all with a giggle all in good fun (this is an industry insider’s joke I didn’t make up), but the reality is a TON of generalized accepted gardening information, recommendations, schedules, instruction, assertions, plant introductions, plant tags, etc. come to us from Zone 5/6 gardeners (discussions of zones another time), researchers and educators.

But the reality is that often such information is totally irrelevant or inaccurate for those of us living in huge regions around the rest of the country; and especially those of us who live in extreme, hot climates, with challenging soils and a very different plant palette, both native and introduced.

Be mindful when seeking out gardening and plant information (or designers and LAs) to remember you often need to get zip code local, and may need to make a lot of changes/substitutions to a technique, recommendation, timing, plant choices, that’s coming to you from someone who has no experience in your environment (me included).

So don’t get frustrated if certain recommendations haven’t worked for you…it may not be FOR you! Or for your particular environmental conditions, both outdoors and indoors. . .

Why is My Yucca Plant Turning Yellow?

It's spring, and many of your plants are pushing out new growth and blooming. But your yucca plant, on the other hand, has started turning yellow! What's going on? Well, you might need to take a closer look at the leaves because you MIGHT just have a few uninvited guests dropping by to suck them dry!

Yucca plant bugs Halticotoma valida (order Hemiptera), which are cousins to other sucking insects such as stink bugs (but much tinier), have already been out in force on my yucca plants for a good month already this spring. I usually try to stay on top of it but I’ve been busy…so the REALLY yellow foliage color today really caught my attention.

Yucca plant bugs are in the order Hemiptera and are related to other sucking pests such as stink bugs and leaf-footed bugs, but are much smaller. Both stages of the insect pierce plant tissue and suck out water and nutrients. This leaves small black dots and a progressive chlorosis (yellowing) of the foliage.

How to Treat Yucca Plant Bugs

Now, I usually don’t treat them - nature usually takes it’s course and my plants are fine; but I’d say this is the worst I’ve seen them. It’s been a particularly cool and humid spring and that’s meant a boom in insect populations.

Due to the severe impact the infestation is now having on the plants, I’ll probably try hitting them with a rotation of alternating insecticidal soap and horticultural oils. But, you really have to get good coverage for these to work as they smother the pests they come in contact with.

There’s no need for me (in this context) to use anything stronger or a systemic pesticide, as again, usually the yuccas pull through with no treatment. In fact, I’ll probably just start with a hard water blast from the hose.

Want better results when starting seeds indoors?

When starting seeds indoors, it's important to manage several environmental conditions...one of those being humidity during germination and sprouting.

When seeds germinate, and the initial but shoot and root initial (radical) emerges, that seedling doesn't yet have root branching or root hairs with which to take up water and nutrients yet. It's surviving off of the resources stored in the seed.

So as the seedling emerges it can quickly shrivel and die if the relative humidity in the space is too low (especially if temperatures around the seedlings are warm or hot due to close grow lights).

You'll need to keep relative humidity (RH) pretty high - around 60% - to keep your young seedlings healthy. You'll need to maintain this RH for several weeks, at least until the seedlings put on their first set of true leaves. Now, this is relative also the species you're growing. Even so, when you're germinating cactus seeds and seedlings, you'll still find higher humidity is going to get you the best results.

Same goes for when you're germinating microgreens seeds.

So, how do you manage to temporarily keep RH high around you seedlings to get them off to a good start? Use a humidity dome!

PC: Leslie F. Halleck

Many humidity domes have top or side vents. After the seeds have germinated and begin growing or cuttings begin to root, you can open the vents to slowly reduce humidity. If too much water begins condensing inside the dome, or you keep the humidity dome on too long, fungal diseases or rot could set in. So if you're using a humidity dome with no vents, you may need to take it off for short periods of time now and then.

Some humidity domes come in taller sizes with a vent you can open and close to conserve or vent moisture and heat. I prefer to use tall humidity domes with vents because it makes moisture management easier, allowing you to grow the seedlings under cover for longer.

If you're germinating a smaller group of seeds, say in a single pot or cup, you can use clear plastic cups turned upside down, or even plastic bags, as a humidity dome. You can also use glass jars or cloche.

If you want to learn more about successful seed starting, check out my book "Plant Parenting" where I guide you step-by-step!

Is your cutting only growing roots with no shoots?

Plant propagation is pretty popular these days. Much of the latest houseplant craze was fueled by a couple specific plants: coin plant (Pilea peperomioides) and fiddle leaf fig (Ficus lyrata). Once more plant parents got their hands on these plants, they of course wanted to try propagating them. But wouldn't you know, not all vegetable plant cuttings are alike, and these two species just happened to throw a lot of first time propagators for a loop. When people tried taking leaf cuttings of both of these species, they may have gotten roots on their cuttings....but never a bud shoot!

Why?

Blind cuttings.

An important thing to know about leaf cuttings is that just because a certain plant can easily develop a callus or adventitious roots on a leaf, petiole, or stem section, it may not be able to develop a new adventitious bud or shoot from that same location. In fact, some leaf cuttings can survive on their roots for a very long time, yet never develop a new bud or shoot. We call these blind cuttings. You'll also see this same phenomenon in Hoya kerrii or heartleaf hoya.

The petiole of this fiddle leaf fig plant can develop roots, but it won’t develop a new bud shoot.
PC: Leslie F. Halleck

Totipotency in Plants

Did you know that not every part or tissue (cell) of every plant can grow roots, or shoots, or both? In each species, each part of the plant - be it the stem, the petiole, or the leaf, each have (or do not have) a particular type of reproductive potential or potency. A seed is an example of plant tissue that has totipotency. That means it contains ALL the necessary genetic information to differentiate into EVERY different type of tissue that plant species will develop. But some plant tissues are pluripotent or multipotent, meaning they may be able to differentiate into some different tissues, not all.

Coin plant, fiddle leaf fig, and heartleaf hoya (to name just a few popular species) won't develop new bud shoots from leaf-petiole cuttings alone. (and none can be propagated just from a leaf cutting). The petiole tissue (the small stem that connects the leaf to the main stem) can differentiate into new root tissue. But not new bud tissue. There needs to be at least some main stem meristem cells attached to the petiole in order to form new bud tissue.

In fact, some leaf cuttings can survive on their roots for a very long time, yet never develop a new bud or shoot.

So if a few of you say "oh you're wrong, MY Hoya kerrii leaf-petiole cutting DID make a new but shoot!" that's likely because there was at least a small piece of main stem tissue still attached to the petiole. It's all about the different types of meristematic tissue that are present in each plant tissue, and that's species specific. (try and take a leaf petiole cutting from your citrus plant and it won't root at all).

And THIS my, plant friends is also why vegetative cuttings of variegated plants that are chimeras (for example variegated Monstera deliciosa) is so difficult. It all comes down to which cells happen to have the genetic code for the variegation (which you won't be able to discern) and are those cells included in the cutting you took.

If you want to learn more about how to take and grow cuttings of your plants, check out my book "Plant Parenting", and if you want to dig deeper into the science of plants and botany, you can join me in my UCLA Botany for Gardeners course.

ICE CUBES: Do they belong on your houseplants and orchids?

You may have heard the recommendation that you water your orchids using ice cubes---that the slow melt of the ice cube will deliver the right amount of water to the orchid over the right amount of time. Lately, I've noticed this recommendation is now migrating over to foliage houseplants. I get asked all the time, especially by my students, if they should or shouldn't use ice cubes to water. I touched on this in my book "Gardening Under Lights", but let's dig a little deeper.

How did ice watering come about?

Well, as a professional horticulturist and long-time avid orchid grower, I watched the ice cube watering method develop as a marketing campaign from within the industry. WHY? Well, orchids used to be few and far between in terms of commercial availability. When I was a budding horticulturist, I had to shell out a pretty penny...we're talking $60-80 for what are now very common butterfly orchids (Phalaenopsis spp.) Eventually, growers figured out production methods that worked well in commercial greenhouse production that allowed for the mass growing and availability of moth orchids (which are generally some of the easiest to grow, that's why the are EVERYWHERE now).

This growing method involves using clear plastic growing pots tightly filled with sphagnum moss. This method allows growers to successfully manage water and nutrients in a controlled environment (versus the looser orchid bark type mix you'll typically see recommended for home growers). These plastic growing pots are then set inside a water-tight cachepot for sales.

The tight root-bound pots with moss, set inside a dark watertight container, become a very-than-ideal long-term growing medium that holds too much moisture for these orchids once they arrive at your home.

• You likely have a LOT less light in your home than where they were professionally grown.
• That likely means you could easily overwater, given the lack of light and the watertight cachepot.

• When customers kill certain plants too quickly, they stop buying them, so...

Orchid growers started actively marketing the "ice-cube watering method" as a strategy meant to mitigate potential over-watering in a less than ideal growing media and environment for moth orchids long term.

As epiphytes, moth orchids generally thrive with much more air flow around their roots, which are adapted to absorbing moisture from humid air and nutrients from surrounding debris that settles around the roots. While professional growers have developed successful management strategies for growing moth orchids en masse using these specific materials and methods, it’s much more likely a home grower will overwater the plants, unless they transplant the orchids to a looser orchid bark mix or more porous containers. The tight plastic sleeve containers and dense moss simply don’t allow for as much air space or drainage. In fact, you may not even be “overwatering”, but the nature of the container and media simply doesn’t allow for enough air flow, even if you aren’t watering too frequently. The ice cube watering method was developed by the orchid-growing industry to help customers to slowly water the plants enough, without overdoing it. Essentially, it’s a work around for a less than ideal long-term growing media and container combination.

If you want to keep your plant long-term and rebloom it, then after it finishes it's initial bloom, I'd remove it from the plastic container and repot your orchid in a container that provides good drainage and aeration, and use a loose orchid potting mix. I guarantee you'll never overwater your orchid again!

Is There any Research on Ice Cube Watering

University research has been performed with ice cube watering methods specifically on moth orchids (but not other houseplants as far as I can find). If done properly, which requires you use three ice cubes and do not allow them to touch any part of the plant, there shouldn’t be any damage to the plants from the initial cold temperature of the ice.

Should You Water Your Orchids with Ice Cubes?

I prefer to use and recommend the standard run-water-over-the-roots-and-out-of the-pot method for a few minutes to introduce more oxygen to the root zone. A good soaking with drainage once per week for moth orchids is standard, but that depends on your environment and if you’ve repotted your orchid into a looser mix. A dry home or repotted plant often requires more frequent watering. (This method of course may not apply to other species of orchids that you grow under glass or in orchidariums, etc...all care methods depend on the species and environment).

Most orchids need a wet/dry cycle---they shouldn’t stay wet all the time.

This is not to say the ice cube method won’t work fine for you for a while. If you keep moth orchids as temporary décor, and expect to replace them every few months after they’ve finished blooming (you can put your spent plants into a compost bin), then the ice cube method is perfectly fine if it’s easier for you. If you’re having success with it long term, then great. But, you’ll need to keep an eye on root health and compaction, and make sure you aren’t seeing root rot develop on plants you intend to keep and re-bloom.

Should You Water Tropical Houseplants With Ice Cubes?

The bigger issue I see at this point is using ice cubes to water all your other tropical houseplants. Temperature aside, throwing a few ice cubes on top of the soil in your potted plants could cause you to underwater the plant (you might be surprised how little water 3 ice cubes may deliver given the size of your container), or simply never get enough saturation lower in the pot. This can cause both lower roots to start to die off from drying out, and result in a build up of salts in your containers. Both are bad news for your plants.

If you use ice watering on houseplants now and then, fine, but make sure your plants get a thorough watering when they need it and you let water run out of the bottom of the pot to leach out built up salts.

DON'T Make Ice Cubes for Your Plants!

Lastly...remember that it takes energy to freeze ice. Environmentally speaking, if there is no real benefit to using ice cubes to water your plants....why burn fossil fuels and put your freezer to work like that? Sure, use the ones you have left over in your cup if you want....but skip making ice cubes just for your plants!

Ever Seen Moss Spores?

Omg LOOK AT HER RECEPTACLES! I admittedly get a case of the vapors when I find such ripe receptacles on liverwort gametangia nestled in a soft tuft of Bryophyta (mosses). HOT.

If you want to hear more dirty talk like THIS you’ll have to join me in botany class through UCLA Extension Horticulture, which starts 4/1/24! A new online section is OPEN for registration (if you’ve been on the waitlist), and you'll learn all about what's going on in this video.

Botany sections fill fast so don’t wait…Let’s go botanize!!