Horticultural Help

08/17/2021

Think Of A Sponge

Someone shared a thought experiment with me years ago that I have often found helpful in understanding how and when to water an indoor plant.

Plant roots require both water and oxygen to survive. It is the potting soil that aids in the supply of both. Think of potting soil as being like a sponge. A good potting mix will be porous with lots of tiny spaces or air pockets spread throughout, just like a sponge. When we water the soil, the air pockets are filled with water and the air is displaced. That is why we sometimes see bubbles percolating to the surface as we water.

Potting soil retains water in the pores and makes it available to the roots throughout the soil. The roots can use just so much water before they need oxygen. We can’t see oxygen and we don’t directly infuse the soil and roots with oxygen. So how do the roots get the oxygen they need?

As soil is allowed to dry out, the tiny pores are once again filled with air or oxygen which is then available to the roots. That is why it is important to let potting soil dry out regularly between waterings. Constantly wet soil is soil that has its pores filled with water. That lack of oxygen will suffocate the roots. This is commonly called “root rot.” But overwatering does not cause a disease that can be treated. It simply causes the roots to die because they have suffocated from lack of oxygen.

Note: Replacing the soil of an overwatered plant does not help. The soil is not contaminated; it is just too wet. The proper remedy is to allow the soil to dry out so that oxygen can once again pe*****te the root zone.

As you know, a very large sponge will take longer to dry out than a very small sponge. That means a pot with lots of soil will stay wet longer than a pot with little soil. Plants in small pots may need more frequent watering. The soil in oversized pots may take too long to dry out and cause root suffocation. That is why unnecessary repotting is not a good idea.

Most houseplants do best when the soil dries out properly every 3-7 days. That guarantees the roots will get the oxygen they need at least once per week and that is what will prevent root suffocation, commonly called root rot.

For most potted plants, it is only the top 20% of the soil that ever needs to feel dry to your touch. That will allow the plants to get the oxygen they need. That means the soil in the bottom of the pot will never need to dry out so there is no need for you to be concerned about checking the soil at the bottom of the pot.

What happens to a sponge that sits in a saucer filled with water for a long time? The sponge stays soaking wet for a long time. The same thing will happen if a plant pot sits in excess water for several days or more. The soil will not dry out and the roots will not get the oxygen they need. That is why you are advised to not let your plant pot sit in water, at least not for more than 24 hours or so.

What happens when a sponge gets completely dried out? It gets hard and water-resistant. To rewet a dried-out sponge, you have to either soak the sponge in water or massage or knead the sponge to get it to absorb water again. The same thing can happen when potting soil gets completely dried out, which it never should. To rewet dried out water-resistant soil in a pot, let the bottom of the pot sit in few inches of water for a couple of hours so the water gets wicked up from the bottom and the soil is completely saturated again. Try to avoid ever letting the soil get that dry.

When watering your house plants, think sponge and think damp but not wet or dry.

08/17/2021

Why Do We Water Once Per Week?

The most common watering recommendation is to water once per week. Although watering by the calendar is not something I recommend there is some rationale behind it that is not often understood.

The roots of plants need regular infusions of water, which we easily understand. But the roots also require a regular infusion of oxygen. That is harder for us to grasp because we can't see oxygen and it is not something we actively apply to plants. Roots get the oxygen they require only when the soil is allowed to dry out sufficiently every week or so. Potting soil is porous like a sponge. After watering those pores are filled with water. As the soil dries out, oxygen returns to fill those spaces in the soil. That is how the roots get the oxygen they require.

Most house plants do best when they get an infusion of water followed by an infusion of oxygen at approximately weekly intervals. If roots go too long without water they dehydrate and start to die. If the roots go too long without oxygen they suffocate and start to die. (Root suffocation is commonly referred to as ‘root rot’ which suggests there is a disease involved. There is not.)

Underwatering means that the soil is getting too dry and the roots are dehydrating. Overwatering means the roots are being deprived of oxygen and are suffocating. Dying roots are the consequence of both. As a plant owner, your goal is to supply a regular infusion of water and oxygen by managing your watering routine accordingly. That means letting the soil dry out appropriately approximately once per week.

There are exceptions of course. Most succulents may not need water more than every two weeks or even longer because they are designed by nature to withstand drought but will easily suffocate if watered too often. Other plants, such as Peace Lilies, come from constantly damp regions and may need more than a weekly watering.

For most indoor plants, weekly watering and drying out is about right. But that does not mean you can water your plants mindlessly by the calendar. You still need to check the soil moisture before you water. If the soil dries out in less than a week, you may need to water a bit more often. If the soil does not dry out appropriately after a week, then your plant may be overpotted and you may need to provide less water when you do water.

08/17/2021

What to do About Exposed Roots

Roots wandering out of pot drain holes and roots exposed on the top surface of the soil attract a lot of attention because they are so visible. The common assumption is that the plant must need a bigger pot so it has more room for those exposed roots. That may seem logical, but that is usually not the best practice for the plant.

Roots grow randomly throughout the pot. Some of them will naturally wander out of the drain hole. That does not mean the pot is too small and is a poor indicator that the plant needs a bigger pot. Those wandering roots can be ignored or simply cut off where they emerge.

As the soil settles in potted plants. Some of the uppermost roots may gradually become exposed. As that occurs, nature protects those roots by covering them with bark-like tissue. (Take a look at the base of a tree outside and you will see lots of above-ground roots covered with bark.) Once those roots have that protective covering, they should NOT be covered with damp soil because it will damage that protective covering. If you don’t like the appearance of the exposed roots, then cover them with an airy top dressing such as Spanish moss that will not smother those roots.

08/17/2021

For Plant Newbies, Beginners, Neophytes & Rookies

Here are some things that you DON’T need to do or worry about. In fact, your plants might prefer that you do less rather than more. Keep it simple.

• Research the Internet. If you do this you will probably come across some daunting, contradictory, and discouraging information about how to care for your new plants. Anybody can and does post online with their pet theories of plant care. Skip the research!

• Repotting. Your new plant does NOT need to be repotted. If you find its plastic nursery pot to be unattractive, then double pot that nursery pot inside another more attractive planter. Leave the soil and roots alone.

• Potting soils. If you don’t need to repot, then you don’t need to buy or use new potting soil. Most potting soils sold today are contaminated with mold and critters that you don’t want in your home.
• Fertilizer. It is overrated and oversold and completely unnecessary for any of your new plants. It will not solve any plant problems or make your plants grow faster. Save your money.

• Misting and raised humidity. All but a few of the most exotic plant species do just fine in normal and low home humidity.

• Quarantining. Check your new plants for visible signs of pests and treat them right away, if necessary. Once treated there is no need to quarantine your plants. (Information on identifying and treating plant pests can be found elsewhere in this group.)

• Gadgets such as moisture meters, plant apps, and self-watering pots. The promise of these plant-care-made-easy devices are rarely realized because they are not very reliable.

So what do you need to be concerned with? It’s a short list.

Light and watering. These two will take care of 90% of plant care issues. Focus on getting proper light and watering for each of your plants and ignore all of the other distractions listed above. If your plants are struggling is is most likely a light or watering issue. That is where your focus needs to be.

You can learn about proper light and watering elsewhere in this group.

08/07/2021

Root Rot – The Phantom Disease

Root rot is an online disease, not a plant disease. A wide variety of leaf and stem symptoms are commonly identified online as being root rot. The implication is that it is some kind of fungal or bacterial disease that must be extricated from the soil. Soil replacement is the commonly recommended remedy. This “root rot” information reflects a fundamental horticultural misunderstanding of what is causing the symptoms that are observed.

What is commonly called root rot is actually root suffocation that occurs when the potting mix is kept too wet for too long. The pores of wet soil are filled with water. Only when soil is allowed to dry out sufficiently, does oxygen return to the pores and provide the roots with the oxygen that they require as much as they require water.

Soil kept wet suffocates the roots and cause them to die. Dying roots will cause a variety of leaf and stem symptoms. If the soil s not allowed to dry out, the root death will progress and the plant will decline further. It s not a disease that is spreading; it is the gradual death of more roots as they are suffocated that is spreading.

Once that is understood, then the remedy becomes obvious and simple – LET THE SOIL DRY OUT more in-between waterings. Replacing soggy soil will not solve the problem. In fact, removing old soil will also remove most of the tiny, threadlike, nearly invisible root hairs that do most of the work. Soil replacement is potentially more damaging to the roots than so-called “root rot.”

One of the risks of moving plants into pots that are too large is that the excess soil retains water for too long and will deprive the roots of the oxygen they need. The roots then suffocate, die, and ultimately cause the plant to decline. Again, the solution is to avoid moving a plant prematurely or unnecessarily onto a pot that is too large. Declaring “root rot” is not helpful.

A properly potted plant will have enough soil so that it dries out within 4-7 days after a thorough watering thereby avoiding root suffocation. (Note: Succulents are an exception and should dry out so deep into the pot that they may need water only every 2- 4 weeks.)

08/07/2021

Easy Plant Care for Beginners

If you have researched how to care for your plants, you no doubt have run into a great deal of conflicting and complicated advice that can make indoor plant care seem overwhelming. Serious plant hobbyists love to dive deep into the particulars of potting soil mixes, fertilizers, watering systems, and humidity devices.

If you just have a few plants that you want to keep reasonably healthy, but would rather not make a big deal over their care, keep on reading and follow these simple instructions.

1. Keep your new plants in their plastic nursery pots so you won’t have to deal with potting soils, new pots, and potting techniques. If you want a more attractive container for your plant, insert the plastic nursery pot and its plant into a planter of your choice. Easy!
2. Most houseplants do best in bright indirect indoor light. That means as close to an uncovered window as possible, but just beyond the reach of the sun’s direct rays. Very few plants will do well more than 5-6 feet away from any window.
3. Let the top half-inch of soil get dry to your finger probe before you give it just enough water for a bit to trickle through the drain holes.

Those are the basics of indoor plant care. Note that there is no need to repot, fertilize, or be concerned with humidity. If you want to keep your plant care simple, you can. Don’t let your research complicate it for you.

08/07/2021

How Much Light Are Your House Plants Actually Getting?

Your indoor plants may not be getting as much light as you think. Evaluating Light for your House Plants is not as simple as knowing which direction the window faces.

LIGHT AND DISTANCE – How far away from the window or primary light source a plant is located makes a huge difference. Light intensity drops off dramatically with each foot of distance away from the source. Light intensity drops to half at a distance of a foot; to one-third at 3-feet away; to one-fifth at 4-feet; and one-tenth at a distance of 5-feet. In general, plants must be within 6-feet of a sunny window that gets lots of direct sunlight and within 3- feet of a north-facing window with indirect light.

Obstructions that reduce the available light are another factor that is often overlooked. Large trees, tall buildings, and window overhangs can reduce light substantially when it reaches your plants. Curtains, blinds, and even sheers block out a lot of light. Even dirty windows and dust on the leaves reduce the light.

Direct sun refers to a location close enough to a window that the rays of the sun fall directly on the leaves of the plant. Because the sun moves during the day some windows provide more hours of direct sun than others.

Bright indirect light is often misunderstood. A location as close to a sunny window as possible but just beyond the reach of the direct rays of the sun on a sunny day qualifies as bright indirect. The farther from the direct sun's rays, the lower the light becomes. A distance of more than 2-3 feet away from the sun’s direct rays will be low light.

Indoor vs Outdoor Sunlight. The outdoor sun is many times more intense than indoor light. Indoors the window glass blocks out most of the UV rays and light typically comes from only one side direction. Outside, the light is more intense and comes from all directions, including overhead. Moving a plant adapted to indoor light outside will often cause serious damage to the foliage
HIGH, MEDIUM, AND LOW LIGHT PLANTS
Many people are surprised to learn that more light is not always better for plants. In fact, the most commonly used indoor plants grow in the deep shade of the tropical rainforest. They have adapted over the eons to live in low light and cannot tolerate direct sunlight. Of course, other plants are suited for direct sunlight because that is what they receive in their natural habitat. These sun-loving plants suffer if they are not in a very sunny window indoors. Finally, there are plants whose light requirements are in the middle range between shade and direct sunlight.
All indoor plants can be placed in one of three light intensity groups:
High light plants must have some direct sunlight for at least several hours per day and bright indirect light for the rest of the day. South and west-facing windows are the best locations for these plants.
Medium-light plants must have bright indirect light all day long and can often tolerate a couple of hours of direct sunlight. East and north-facing windows are the favored locations for these plants.
Low-light plants must be protected from direct sunlight at all times. They thrive in bright indirect light, but will often tolerate minimum light levels. These plants prefer locations close to a north window or away from an east, west, or south-facing window where they are protected from the direct rays of the sun.
Symptoms of Inadequate Light – Plants that are not receiving enough light often have a spindly, elongated, stretched-looking appearance. The space between the nodes (the point where the leaf attaches to the stem) on the stem is elongated. The leaves themselves are often small and puny-looking. These are NOT signs of inadequate nutrition so do NOT fertilize plants with these symptoms. Prune them back and provide more light for them. That is the only remedy.
Symptoms of Too Much Light – Too much light will cause plant foliage to turn pale green or yellow and in extreme cases brown and dry. Contrary to what some ads suggest, adding plant food will not restore the color to these bleached-out leaves. The solution is to protect the plant from the direct rays of the sun by moving the plant or by covering the window with a sheer curtain. Foliage tissue damaged by excess light will not recover, so trim it off.
Once you have your plants situated in the right light, you have taken a major step toward having a green thumb and maintaining healthy plants.

08/07/2021

Understanding a Fertilizer Label

I have resisted posting this information because it is not important for the vast majority of house plant owners. Manufacturers, retailers, and serious hobbyists make far too much out of fertilizing. For professional growers fertilizing is important, but for the average layperson, it is not. That is because indoor house plants use nutrients in very minute quantities, rarely need fertilizing, and only at half-strength a few times a year.

But I recognize that some folks are curious about plant labels and some folks do want to know more, so I m posting some basics here. But I can't emphasize enough that fertilizing is just not very important for almost all plant owners. Fertilizer is NOT medicine. It is intended only for healthy plants that are growing vigorously and have been in the same potting mix for a year or more. Those are the only plants that may have depleted enough of their nutrients that they may benefit from fertilizer.

The three numbers listed on fertilizers are, in order, nitrogen (N), phosphorous (P), and potassium (K) or N-P-K. Those are the three major elements that all plants require. There are also less important elements called minor or trace elements that plants also use but in much smaller quantities, so they may not be listed on the label.

⁠A 3-1-2 ratio means that fertilizer has three times more nitrogen than phosphorous and twice as much potassium than phosphorous. That is the proportion that most indoor foliage plants use. Nitrogen is most needed for leaf growth; phosphorous is more important for flowering, and potassium is a basic building block.

Nitrogen tends to be depleted more than the other two major elements. That is why it has a higher number. Higher overall numbers, 15-5-10, for example simply mean that the fertilizer is more concentrated and will need to be diluted more, as per the label instructions.

The dilution rates on the label reflect optimal greenhouse growing conditions. That means most houseplant owners should dilute by half the recommended rate listed. If the label says 1 tsp per gallon, then use one-half tsp per gallon. Using too much fertilizer is a much more common problem than not using enough.

Brand names of fertilizers are meaningless. And so are other marketing terms such as all-natural, organic, better growth, stronger plants, etc. Claims of including vitamins, hormones, and other exotic ingredients are bogus. Plants are not people and they do not need vitamins and hormones.

Fertilizer concentrates labeled as ready-to-use or RTU usually do not require dilution with water because they have already been diluted. That may save you some trouble (not much!), but it means you are paying as much or more for a diluted product that is mostly water.

Powders and liquid concentrates are preferred because they are easier to dilute. Timed-released fertilizers are pellets that release a small quantity of nutrients at each watering and last anywhere from 3 months to a year, as stated on the label. However, along with that convenience, there is a loss of control. If your plants stop growing or develop any problems, the fertilizer pellets will continue to release nutrients even when they are no longer needed.

Fertilizer spikes are easy to use, but they create nutrient “hotspots” near the roots where they are inserted. For that reason, they are not recommended.

⁠More important than understanding all of this is that most of this does not matter. Fertilizing is one of the last things you need to be worried about when caring for your plants. Focus on proper light and water instead.

08/07/2021

Deciding When To Water

I often ask people how they determine when it is time to water their plants. Surprisingly few are using a reliable method to determine when to water.

Some people just rely on the calendar – “I water every Monday morning.” Others wait until the leaves wilt or droop. Some say they “water when dry.” Some admit they don’t have a system and just water when they think about it. Others rely on the weight of the plant and pot when lifted. Using a moisture meter or a plant app are also common methods cited.

But plants do not know about calendars. Waiting for leaf symptoms (wilting, drooping, yellowing) to appear means you have waited too long. Watering when dry means different things to different people. For some, that means when the surface of the soil feels dry while for others that means when the soil is dry at the very bottom of the pot. Random watering may work for a while but eventually, it leads to failure. Pot weight varies from one size plant to another, one potting mix to another, and one type of pot material to another. And is very difficult to track accurately. Moisture meters are notoriously unreliable because they vary from one potting mix and plant to another. Plant apps rely on statistics not the actual needs of individual plants.

So what does work? Using your finger or a mechanical soil probe is the most reliable method for knowing when to water.

Background: Plants get the water they need through their roots, not their leaves. If the roots get too dry they desiccate. If they stay too wet they suffocate. In either case, the roots will be damaged and/or may die. That prevents them from properly absorbing the water needed by the rest of the plant. So it is the moisture in the soil around the roots that matters most.

For most non-succulents, the top layer of soil in the rootzone should get almost dry to your touch before you water. For succulents, the soil needs to dry about halfway to the bottom of the pot.

Using your finger to determine soil moisture does take some experience and practice, but ultimately it is far more reliable than other methods. By checking the soil moisture before you water you will be able to make adjustments for seasonal changes in light and temperature. If the soil dries out sooner due to high temps or more light or drier air, then your finger will let you know.

Here is an important consideration. If loose soil has been added to the top of the original rootball of a plant – a common mistake made when plants are repotted – then that will cause you to miscalculate the soil moisture. Avoid this by removing any soil from the top surface that is not in immediate contact with the uppermost roots. Then you will be able to probe the upper half-inch or so of the rootzone soil to determine when it is time to water.

08/07/2021

Things I have Wasted My Money On

As the owner and lover of thousands of indoor plants over many decades, I have paid close attention to a wide variety of products that I thought might be useful. As it turns out, most of them were a waste of my time and money. Few deliver on their marketing promise. But there are a couple of exceptions that have been of great value. I am posting this so you won't make some of the wasteful mistakes that I made!

Moisture meters are seductive because they seem to provide scientifically precise analysis of exactly when to water your plants. I used these devices personally and professionally for years before I realized that they often defied what my common sense was telling me. But I tended to assume the meter was smarter than me. Now I understand that moisture meters don’t measure water directly. They measure electrical conductivity. Because one potting mix is different from another, you never know what your meter is reacting to. Moisture meters are better as marketing tools than as plant care tools. Save your money and trust your sense of touch!

Fertilizer and Other Supplements. The manufacturers and retailers of these products know a good profit center when they see it! The commonly promoted fertilizer use guidelines are based on greenhouse conditions that none of us has in our homes. House plants use nutrients in very minute quantities. Fertilizer is not medicine and it should never be used with ailing plants. It is intended only for healthy plants that are growing vigorously and have not been repotted in at least a year. Even then, the fertilizer should be used only at half strength.

Most any commonly available fertilizer is adequate, so shopping by price probably makes the most sense. Organic or "natural" fertilizers have their proponents, and they are fine but have little proven value over commercial products. Ignore label claims about all the wonderful things that the fertilizer will accomplish. Fertilizing should be one of your least concerns with plants care.

Avoid using food products that will not compost indoors, but may cause odors and attract pests. And pass on those miraculous supplements that claim to include hormones, vitamins, and other magical ingredients that plants can't use. Most of those supplements are 99% water and sold at an inflated price.

Potting soils are another big source of profit for retailers. There are thousands of brands and formulations available online. All make exaggerated claims as to their effectiveness. They imply that if your plants simply have better soil they would thrive. They encourage you to replace the existing soil that your plants were grown in with something better. But replacing soil is one of the worst things you and o to your plants. Doing so does serious damage to the roots. The best soil for any plant is the soil it has been gown in and the roots are adapted to.

Unnecessary repotting is another common problem that is best avoided. Only if a plant needs a thorough watering more than every 3 or 4 days does it need a larger pot. In such circumstances or if you are potting starts, then the best potting mix will be primarily peat moss or coir with about 25% perlite mixed in. You can save a lot of money by mixing your own.

Self-watering pots rarely deliver on their implied promise. They don’t automatically supply your plans with the right amount of water just when they need it. Some self-watering planters work better than others. The better ones, such as Lechuza systems work well when set up carefully, but they are also quite expensive. At best, self-watering planters will extend the interval between waterings. That will allow you to go 2-4 weeks without filling the reservoir. But it still requires you to know just how much water your plants use and you're setting up the system properly. They are not mindless no-brainers!

I invested in a variety of home humidifiers and misters in the past. It was only after taking care of plants in office environments where there were no such humidifiers available that I learned two things. One was they in dry winter air, the soil dries out sooner than in moister air. The second was that as long as I watered more frequently in dry air, then the low humidity was not an issue.

Rooting hormones are of marginal value for home propagation of plants. The key to rooting success is using a good rooting medium and keeping it at just the right moisture level. Rooting powder will not enhance either of those.

To end on a more positive note, there are some products that I can recommend as reasonable investments

A soil probe, such as Soil Sleuth (www.soilsleuth.com) is an inexpensive tool that allows you to sample soil moisture at different depths in a pot. It is cheaper and more reliable than a moisture meter.

Foliage-Pro by Dyna Gro is a good all-purpose fertilizer that has all the nutrients that plants need and in the right proportions. It is the same formula that many professional growers use. I do recommend that you use it at only half the recommended label strength and only with healthy plants that are growing vigorously.

Pro-Miix Potting Mix is a good quality potting mix for all your indoor plants. It is a sterile mix and I have never had any pest or disease problems with it. You may want to mix in some additional perlite to make a more porous potting mix for plants, such as succulents, that you want to dry out sooner.

Brand-X Foliage Cleaner is the best cleaner of plant leaves that I have found. It is used by plant professionals and is only available to consumers at (www.BuyBrandX.com) It sprays onto plant leaves and it dries to a hard, non-oily finish. It rinses away water and fertilizer stains. You can dilute it with water to get just the right amount of shine that you prefer. It is harmless to any hard-surface leaves but should be used only on hard-surfaced leaves. Although it is not a pesticide, it does contain silicon which can pe*****te very tiny plant crevices where scale and mealybugs tend to hide. I have found it to be highly effective in treating persistent scale and mealybug problems.

Soil probe detects moisture level and aerates plant roots, made in USA and designed by interior plantscaper. For indoor pots or outdoor use.