Good Gardening Practices

8/3/2019 Good Gardening Practices

1/8

Good Growing Practices - an Overview for Beginners

My hope is that this thread becomes a gathering place for beginners and the experienced

alike, a place where reliable information that is rooted in sound science and horticulture

can be found. Well see how that gathering part goes, but I have enjoyed enthusiasticparticipation on many of my other threads, so I am optimistic.

As I consider what I am going to share with you and how to go about sharing it, I amcompelled to offer some background that will hopefully allow you some degree of

comfort in placing some measure of value on my commentary. I enjoy the growing

experience tremendously. I have worked hard toward increasing my skill level for more

than 20 years, and I look at sharing what I have learned about the growing sciences as anatural extension of the enjoyment I get from nurturing plants - sort of nurturing people

who nurture plants. I am invited to lecture frequently in the mid-MI area, and

occasionally beyond. I lecture, conduct workshops, and do demonstrations on a variety of

subjects related to growing, but most frequently I talk about things related to containerculture, with maintaining houseplants being one of the most requested topics. I also enjoy

participating here on Daves and at another popular garden forum. Hopefully we will beusing some links to some of my other offerings here that will help you share some of the

confidence others have in the reliability of my offerings. Those that know me know I am

not after recognition or glory, I simply feel I can help any beginner with a willingness to

learn and apply the newfound information, as have so many others, and I get a largemeasure of personal satisfaction from the feeling I may have helped someone along the

path to becoming a better grower.

The first challenge is to offer information that a beginner can digest, and in such a way

that he or she feels it is important enough to act on. I am first going to flesh out the mainissues that, if understood, will make anyone a better grower and hope Ive created enoughinterest that there will be plenty of questions so I can go into greater detail in the answers.

For what it is worth, I tend to look at growing anything in containers from the perspective

of what is best for the plant, not what is best for the grower. Far more often than not, thetwo ideas are mutually exclusive, so if grower convenience is a large priority of anyone

reading this, there is not much sense in reading on. Growing well does take a little

thought and a little effort.

The houseplants we grow are perennials nearly all, capable of growing for many, many

years and of being passed from generation to generation. With attention to the areas Ill

cover in this post, you will discover you can maintain your plants in good health for aslong as you continue to commit to providing favorable cultural conditions. Your plants

are all genetically programmed to grow well and look beautiful. It is only our lack of

knowledge and skill in the area of providing the cultural conditions they prefer thatprevents them from growing to their potential. That sounds harsh, but its the truth.

I have never seen anyone other than me discuss growing plants in containers from this

perspective, that is (and it bears repeating) your plants are already genetically


2/8

programmed to grow well and look beautiful, but its up to you as a grower to

eliminate the limitations so often associated with growing in containers. This post is

about isolating some of the factors that are commonly the most limiting and helping youto reduce the limiting effects. For more information on the concept of limiting effects, do

a search using the words Liebigs Law of the Minimum

Soil choice - Growers should realize that the most important choice they will make

when establishing a new planting or when repotting is their choice of soil . A poor soil

is probably behind more than 90% of the issues that growers come to the forums seekingremedial help for. Collapsed or dead plants, spoiled foliage, insect infestations, disease

issues are all symptoms usually traceable directly or indirectly to a poor soil. This is so

important to understand, that I will devote the bulk of my effort toward making it clear

why I offer this contention.

Light is extremely important to plants. Plants make their own food, using water, CO2,

and energy from the sun. Inadequate light means the plant cannot make enough food to

grow to the potential it was genetically programmed for. I will not go into great detailabout light because when it comes to houseplants, you either have good light or are

forced to deal with the limiting effects of inadequate light. If the thread takes off, we candiscuss supplementing light and how to prune to help compensate for the leggy

appearance caused by insufficient light, or other topics of interest relating to light.

Nutrition supplementation is a requirementfor normal growth and good health whengrowing plants in containers. In the earth, many of the nutrients are supplied by minerals

in the soil. Container soils usually have no mineral component (and it is best that they

dont in most cases - more later), and the sol components break down so slowly and arewashed from the soil so quickly that deficiencies are virtually assured if you do not

fertilize.

Repotting vs. potting up - that there is a difference is a concept foreign to most hobby

growers. One practice ensures your plants will at least have the opportunity to grow to

their genetic potential within the limits of other cultural conditions; that would berepotting, with its accompanying root maintenance, complete or partial bare-rooting, and

a change of soil. Potting up, on the other hand, only temporarily allows the plant to grow

a little closer to its genetic potential before root congestion and a lack of fine roots

quickly returns the plant to the state of limited growth and vitality it was experiencingbefore potting up.

Watering habits - extremely important and inextricably linked to soil choice, which iswhy I saved it until the end - so it would lead me back to the most important

consideration - the one most apt to determine the difference between frustration and a

rewarding growing experience.

Air is as important as water in soils. Plants absolutely love plenty of air, and rebel very

quickly at too much water in the soil. Im going to describe what happens when you

water plants growing in a soil that retains too much water. There are actually two


3/8

possibilities. The first is, you water, and a part of the soil near the bottom of the container

does not drain. This water has a name, it is called perched water, so named because it

perches (like a bird) in the soil above the pot bottom. This excess water is criticallyimportant because it very quickly begins to kill roots growing near the bottom of the pot,

within hours. The first roots to die are the roots that do the lions share of the work - the

very fine roots often referred to as hair roots. The longer the soil remains saturated, thelarger the diameter of the roots killed. When air finally returns to this once saturated soil,

roots then begin to regenerate. This takes energy and is extremely expensive to the plant

in terms of that energy outlay. The plant is actually forced by chemical messengers thattell it to grow roots, to direct energy that would have gone into growing more leaves,

branches, blooms, fruit, or just increasing the overall mass of the plant, to replacing the

lost roots.

The second thing that might happen when you water if you are using a water retentive

soil is, you water in small sips to prevent root rot. It makes sense to only give the plant a

little water at a time - right? That might be a workable option if you have the luxury of

using water that has been processed through a reverse osmosis water filter, or if you arewatering with distilled water, but regular tap water has things dissolved in it, like

magnesium, calcium, iron, sulfur, and others. If you water in sips, these dissolved solidsremain in the soil and build up over time. This has an impact on the plants ability to

absorb water and the nutrients dissolved in water. To illustrate the potential impact these

dissolved solids have on a plant, picture in your mind what curing salt does to ham or

bacon. It literallypulls water from the cells & dries out the meat. Any solute in thesolution surrounding plant roots can have the same potential effect on plant cells. It can

make it difficult for plants to absorb water and nutrients, it can make it impossible, and in

some cases can actually reverse the flow of water so it moves OUT of cells, effectivelycollapsing and killing them. We commonly call this fertilizer burn, but it doesnt

necessarily have to result from an over-application of fertilizer. When people come here

wanting a remedy for foliage that is dying, with dried edges & tips, its almost alwaysfrom over-watering and the accompanying limitation that has on root function and

metabolism, or a high level of dissolved solids from fertilizers and tap water having

accumulated in the soil making it difficult for the plant to take up water. Misting cannotcorrect a problem related to over-watering or a high level of solutes in your plants soil.

Low humidity can be a contributingfactor to the common symptoms of necrotic (dead)

leaf tips and margins (edges), but for the actualcause, look to impaired root function

from over-watering or a high level of dissolved solids in the soil. BOTH of theseconditions are nearly always linked to a poor soil.

When using water-retentive soils, it seems almost as though we are on the horns of adilemma. If we water generously, we risk the soil remaining saturated so long it causes

root rot, or at a minimum - impaired root function. If we water sparingly, in small sips,

we risk an accumulation of dissolved solids from tap water and fertilizer solutions in thesoil so what to do? Well - I think we should look at an option that solves both issues

and makes things much easier for the grower, while also providing the grower with

considerably more latitude when it comes to watering and fertilizing.


4/8

The factor that determines how water retentive and difficult to grow in a soil is, is the size

of the particles it is made from. The smaller the particles - the greater the water retention

and the greater the degree of difficulty for growers. Soils made of any combination ofpeat, coir, compost, sand, topsoil, and other fine particulates are going to be very water

retentive, which we know is undesirable from the perspective of the plant, and they

cannot be suitably amended to correct drainage or the height of the perched water byadding perlite or other drainage material. If anyone disagrees with that statement, please

ask for an explanation before mounting an argument or offering individual observations.

Adding perlite to soils reduces the overall water retention of the soil, but it does nothingmeasurable for drainage (flow-through rates) or the height of the perched water table, the

later being the critical consideration when it comes to a healthy root zone.

Soils made of a high % of pine bark or other inorganic particles will have lots of large airspaces called macropores. These are pores that will not hold water, only air, even when

the soil is as saturated is it can be. They are critical to a healthy root zone. If you build a

soil with plenty of air space, it hardly matters what the soil is made from. What is

important is how the soil is structured. I will grow a perfectly healthy plant in a bucket ofbroken glass on a dare and a wager if anyone is interested in taking me up on it. If you

have a soil with a healthy structure, a good nutritional supplementation program, andhave good available light, the rest is so easy anyone can do it - honest. Ive seen it happen

over & over and over again. You will not go wrong if your primary focus is providing a

healthy - a truly healthy environment for roots. Roots are the heart of the plant. Roots

come first. If you cannot keep the roots happy, there is no chance you can keep the rest ofthe plant happy. That was a paraphrased quote from Dr. Carl Whitcomb, PhD, who wrote

the bible on Plant Production in Containers.

This ends the beginning discussion about soils. Until you are able to grow plants, thegrowth rate and appearance of which you are happy with, focusing on removing the

limitations placed on your plants by soil choice will almost always constitute the best

use of your energies. After reading this far, if nothing else, I hope you take that from

this offering. It is the most important point and the best piece of advice I can give

you. If you are interested in knowing HOW to make soils that will help you remove

the limitations, now is the time to ask.

Nutrition is an area that is very misunderstood when it comes to container culture, but it

is actually very easy. Its also very easy to become confused because there are so manynumbers that represent different fertilizer NPK percentages and so many different kinds

of fertilizers. I will need to use some numbers, but I think an understanding of NPK

percentages as opposed to fertilizer RATIOS is important. NPK %s tell us how much(N)itrogen, (P)hosphorous pentoxide, and (K) potassium oxide (the symbol for potassium

is K) are in a fertilizer by weight. So a fertilizer that is labeled All Purpose 24-8-16 is

24% nitrogen, 8% phosphorous, and 16% potassium. 12-4-8 is also a common all-purpose fertilizer. It has exactly half the nutrients of 24-8-16, but both are 3:1:2 RATIO

fertilizers. Ratios are a way of describing the amount of nutrients in a fertilizer as they

relate to each other. Why is this important? It is important because we know that on

average, plants use about 6 times as much N as P, and they use about 3/5 as much K as N,


5/8

and now I will tell you how we can use this information to our plants advantage.

The ideal way to fertilize is to supply fertilizer at the same ratio in which plants use thenutrients. The reason is because optimal growth and vitality can be had only when

nutrients are in the soil at overall levels low enough that it doesnt become difficult for

plants to take up water and nutrients dissolved in that water. Remember what we saidabove about a high level of soluble in the soil making it difficult for roots to absorb water

and nutrients? Nutrients also need to be present at levels high enough to prevent

deficiencies. If we think about it for a second, we can see that the best way to achieve thisend is to supply nutrients at the same ratio in which they are used.

I noted that the NPK percentages actually tell us how much phosphorous pentoxide and

potassium oxide are in a fertilizer so I can show you how fertilizer manufacturers arrivedat a 3:1:2 ratio as their all-purpose blend. Only 43% of the P reported on a fertilizer

label is actually P, and only 83% of the K reported is actually K. Once you apply these

factors to any of the 3:1:2 ratio fertilizers (24-8-16, 12-4-8, and 9-3-6 are all popular

3:1:2 ratios, youll see they supply nutrients in almost exactly the same ratios as theaverage that plants actually use, and these fertilizers are excellent at keeping overall

levels of soluble as low as they can be without nutritional deficiencies.

There is no need to usespecialty fertilizers; and many specialty fertilizers, like the

advertised bloom boosters with up to 30 times more phosphorous than a plant could

ever use (in relation to the amount of N used) can be moderately to severely limitingbecause the excess nutrients are a limiting factor.

The question often arises, Should I use a synthetic or an organic fertilizer? The answeris: Use whichever you wish; but the qualifiers are: Organic fertilizers are actually more

accurately called soil amendments. They are mixed into the soil in the hope that at some

point soil organisms will digest them and make them available in elemental form soplants can absorb them. The problem with that approach is that the populations and

activity of soil life populations in containers are erratic and unreliable, making the

delivery of nutrients from organic sources just as erratic and unreliable. What you applytoday, may not be available until next month, and there is no way to determine what

residual amounts of which elements remain in the soil. Soluble fertilizers like Miracle-

Gro and others are completely available as soon as applied, and we know exactly what

our plants are getting. They are simply much easier to use and deliver nutrients muchmore reliable than other fertilizer types. You can lump controlled release fertilizers like

Osmocote and others in with the soluble synthetic fertilizers. With them, you get an extra

measure of convenience but sacrifice a measure of control. As with all fertilizers, it isimportant to note the NPK percentages to be sure you are supplying the fertilizer in a

favorable ratio if you want your plants to be all they can be.

It isnt going to kill your plants if you use a fertilizer with a less favorable ratio because

plants tend to take the nutrients they need from the soil (solution) and leave the rest, but it

is important to understand that it is the rest that constitutes a limiting factor, so avoiding

excessively high levels of any one nutrient whenever possible is to your (plants) benefit.


6/8

As noted above, most growers draw no distinction between repotting and potting up. I

have spent literally thousands of hours digging around in the root-balls of containerizedplants. Old plants from nurseries of greenhouses are probably the closest examples to

what most houseplants are like below the soil line, so I'll offer my thoughts for you to

consider or discard as you find fitting.

I have helped salvage many plants that had been containerized for long periods and were

circling the drain. Not long ago, our bonsai club invited a visiting artist to conduct aworkshop on mugo pines. The nursery (a huge operation) where we have our meetings

happened to have purchased several thousand of the mugos somewhere around 10 - 12

years ago and they had been potted up into continually larger containers ever since. Why

relate these uninteresting snippets? In the cases of material that has been progressivelypotted-up only, large perennial roots occupied nearly the entire volume of the container,

plant vitality was in severe decline, and soil in the original root-ball had become so hard

that in some cases a chisel was required to remove it.

In plants that are potted up, rootage becomes entangled. As root diameters increase,

portions of the roots constrict other roots and impair the flow of water and nutrientsthrough them, much the same as in the case of girdling or encircling roots on perennials

grown in-ground. The ratio of fine, feeder roots to more lignified (woody) and perennial

roots becomes skewed to favor the larger, and practically speaking, useless roots.

The initial symptoms of poor root conditions are progressive diminishing of branch

extension on plants that branch, loss/shedding of foliage on the parts of branches nearest

to the trunk, often giving the plant a poodle look, and reduced vitality. As rootagebecomes continually compressed and restricted, branch extension stops and individual

branches might die as water/nutrient movement is further compromised. Foliage quality

may not (important to understand) indicate the tree is struggling until the condition issevere, but if you observe your plants carefully, you will find them increasingly unable to

cope with stressful conditions - too much/little water, heat, sun, etc. Trees that are

operating under conditions of stress that has progressed to strain, will usually bediagnosed in the end as suffering from attack by insects or other bio-agents/disease while

the underlying cause goes unnoticed.

I will mention again that I draw distinct delineation between simply potting up andrepotting. Potting up temporarily offers room for fine rootage to grow and do the

necessary work of water/nutrient uptake, but these new roots soon lignify, while rootage

in the old root mass continues to grow and become increasingly restrictive. The largerand larger containers required for potting up & the difficulty in handling them also makes

us increasingly reluctant to undertake even potting up, let alone undertake the task of

repotting/root-pruning, which grows increasingly difficult with each up-potting.

So we are clear on terminology, potting up simply involves moving the plant with its root

mass and soil intact, or nearly so, to a larger container and filling in around the root/soil

mass with additional soil. Repotting, on the other hand, includes the removal of all or part


7/8

of the soil and the pruning of roots, with an eye to removing the largest roots, as well as

those that would be considered defective. Examples are roots that are dead, those

growing back toward the center of the root mass, encircling, girdling or j-hooked roots,and otherwise damaged roots.

I often explain the effects of repotting vs potting up like this:I will rate growth/vitality potential on a scale of 1-10, with 10 being the best. We're going

to say that plants in containers can only achieve a growth/vitality rating of 9, due to the

somewhat limiting effects of container culture. Lets also imagine that for every year aplant goes w/o repotting or potting up, its measure of growth/vitality slips by 1 number,

That is to say you pot a plant and the first year it grows at a level of 9, the next year, an 8,

the next year a 7. Also imagine please, we're going to go 3 years between repotting or

potting up.

Here's what happens to the plant you repot/root prune:

year 1: 9

year 2: 8year 3: 7

repotyear 1: 9

year 2: 8

year 3: 7

repotyear 1: 9

year 2: 8

year 3: 7You can see that a full repotting and root pruning returns the plant to its full potential

within the limits of other cultural influences for as long as you care to repot/root prune.

Looking now at how woody plants respond to only potting up:

year 1: 9

year 2: 8year 3: 7

pot up

year 1: 8

year 2: 7year 3: 6

pot up

year 1: 7year 2: 6

year 3: 5

pot upyear 1: 6

year 2: 5

year 3: 4

pot up


8/8

year 1: 5

year 2: 4

year 3: 3pot up

year 1: 4

year 2: 3year 3: 2

pot up

year 1: 3year 2: 2

year 3: 1

This is a fairly accurate illustration of the influence tight roots have on a plant's

growth/vitality. You might think of it for a moment in the context of the longevity ofbonsai trees vs the life expectancy of most trees grown as houseplants, or the difference

between less than 4 years versus more than 400 years, lying primarily in how the roots

are treated.

I have not yet mentioned that the dissimilar characteristics of the old soil as compared to

the new soil when potting-up also carries the potential for trouble. With a compacted soilin the old roots and a fresh batch of soil surrounding the roots of a freshly potted up plant,

it is nearly impossible to establish a watering regimen that doesn't keep the differing soils

either too wet or too dry, both conditions occurring concurrently being a limiting factor

and the rule rather than the exception.

Most who read this would have great difficulty showing me a containerized plant that is

more than 10 years old and as vigorous as it could be, unless it has been root-pruned atrepotting time; yet I can show you hundreds of trees 20 years to 200 years old and older

that are in perfect health. All have been root-pruned and given a fresh footing in in new

soil at regular and frequent intervals, the same treatment all my houseplants get.

Thanks to any/all who made it this far. This is only an overview, but with even a

rudimentary understanding of how to go about reducing the effects of the limiting factorsthat restrict growth and vitality, I know you can improve on how well your plants can

grow, as well as on the degree of satisfaction you get from your growing experience - my

only reasons for writing this. Hopefully the offering leaves you with many questions.

Documents

Good Gardening Practices