Category: Plants

Posted on

Perched Water Table

Understanding the perched water table really helped give me a better understanding of what it means to take care of plants.

Most containers will form a perched water table at the bottom, but they also occur when there is a sudden change in soil consistency, such as from clay to sand, or soil to gravel.

A layer of gravel in your container creates a higher perched water table that is more in the root zone of your plants, with adverse effects on plant growth and root formation. The gravel raises the perched water table in the bottoms of pots. Gravity can't quite pull all of the water from the bottom of the soil so it stays wetter than the rest of the pot and anaerobic.

The gravel takes up some space at the bottom of the pot so the transition zone is higher up in the pot where the soil and gravel meet, and potentially closer to the roots.

As you can see the perched water table occurs because of the bottom of the container, not because of the ground. As long as it's deep enough for your roots, you should be fine! And some species do prefer wetter soil too.

The reason that it is called the perched water table is due to soil retention.

I've literally never seen proper container soil sold anywhere, you need to make it yourself. Tapla Soil Retention is what forever changed how I go about preparing the soil for my pots. How? Now I make proper soil.

5-1-1 Mix

I idealy I try and mix my soil like this (based on Al's recip from Garden Web):

  1. 5 parts pine bark fines, dust – 3/8 (size is important)
  2. 1 part sphagnum peat (not reed or sedge peat please)
  3. 1-2 parts perlite (coarse, if you can get it)
  4. garden lime (or gypsum in some cases)
  5. controlled release fertilizer (if preferred)

Small Mixture

  1. 3 gallons pine bark
  2. 1/2 gallon peat
  3. 1/2 gallon perlite
  4. 4 tbsp lime (or gypsum in some cases)
  5. 1/4 cup CRF (if preferred)

Any peat based potting media should be replaced yearly, 5-1-1 every two years or so, but the gritty mix will last for ages without losing pore space. All my potted perennials are grown in gritty mix now.

~XO

Posted on

On Repotting Plants

When I first started out, new apartment, new responsibilities, and new plants I didn’t do as well as I expected. Live and learn. I am not the type of person that accepts defeat well; I learn from my failures, I do better. My potted plants were the biggest failure, and they also held the most value in my life. My mother and grandmother both donated plants that they had cared for for years. They were sort of like family members. All but one died under my care. My mistake? Repotting? Potting up? My real mistake is that I was trying too hard, I wanted to do it “right” and in the end did it wrong.

Repotting/Potting Up

Soil in nature is constantly changing. New organic matter is being broken down, the soil is aerated by things living in it. Much of this doesn’t happen in the artificial environments we make for our plants, so we have to put a little effort into their care ourselves. For most plants, they can go a few years without being repotted, although most will survive in the same soil for a LONG time. You don’t need to replace all of the soil when you refresh or repot it. Just loosen up the roots a little and some of the old soil will fall out. Both replace soil, but only one will replace the container. Plants grow, and their roots will outgrow the container limiting the size of the plant, this is what is known as being root bound. There’s two ways to fix this. One is to transplant it into a larger container, but obviously you’re going to have to limit it at some point which brings up your second option, trimming the roots(and foliage). If your plant is root bound to keep it healthy and in the same container just take it out and cut off the outer layer of roots, maybe 1/5th of the total roots, and replace that now empty space with fresh dirt. You’ll likely also have to trim the foliage back if that’s getting too large. The second problem you’ll run into in never switching pots is your soil will run out of nutrients and this can be solved by fertilization, or if it’s a low nutrient plant simply replacing the soil as mentioned above may be enough. What and how much you should feed your plants will be depends on the type of plant you have so there are no general answers there. If you keep the other aspects under observation, a plant’s soil can go a long time. In fact I don’t plan to replace the soil in my potted plants soil for the next 10 years. You’ll be pleasantly surprised with what you don’t have to do. Soil doesn’t go “bad” but the particles do break down. And in a closed system of a container, there isn’t a full ecosystem of soil organisms to aerate the soil. And you can get a lot of salt deposits that accumulate in your soil after years of watering. But repotting becomes important when the soil particles have broken down. This is usually once they have broken down to the point that the smaller particle size of the medium interferes with aeration of the roots.
Posted on

Potted Plants a Sort of How-to

The reason why I decided to post this today is because it is something that I have been working on for a while, and I can imagine that others ave struggled with it before as well. Indoor plants, they seem like a lot of work, and for me they were until I learned what I was doing wrong. Six factors affect plant growth:
  • air,
  • water,
  • light,
  • temperature,
  • soil,
  • nutrients.
Whichever of the six is will limit your plant. For example: Potting plants in the correct soil will help eliminate 90% of problems a plant may experience. Give your plants the right soil, and you position them to thrive and reach their full genetic potential. The right soil will yield healthy roots, which in turn yields a healthy plant.

Succulents

For succulents, water, light, and temperature are pretty well understood. For example, we all know a succulent without enough light will stretch (called etiolation). Obviously, it’s seeking more light. But what we might not know is that behind the scenes, the plant is putting extra energy into stretching. This could lower the plant’s immune system, making it more prone to pests and infection. So where do we start when trying to provide our succulents with a better environment where they will not only survive, but thrive?

It Is In The Dirt

A plant’s roots play a role in receiving all but one of the six elements: light. One particularly important but often neglected element, here, is air. Roots need oxygen and airflow as much as they need water. This is why root rot happens. It’s not because of too much water, but rather because water can cause a lack of oxygen to the roots. Think about this for a moment; if water were the issue, how could plants and even succulents grow hydroponically? They could not. They water needs to have oxygen in it for them to develop a healthy root system. Air is the reason why a gritty mix is so good for plants. It is a potting medium that, when done correctly, completely eliminates the issue of “overwatering” by eliminating the layer of water at the bottom of the pot that suffocates the finer roots – the ones that do the most work in getting your plants water and nutrients.

Drainage

The most important aspect of a container is a drainage hole. This is non-negotiable if a plant is to survive for than a few months. A pot without a drainage hole nullifies all the advice above. Even with a gritty mix, it is impossible to keep a plant healthy without a drainage hole. A plant in a container with no drainage hole will either be under watered due and experience fertilizer burn due to watering in sips, or conversely over watered with its roots sitting in water. If you would like to have your plant in a container that is not perfectly suitable for plants, such as a cute ceramic planter with no holes, an old shoe, or a glass terrarium, use a cachepot. That is, use a normal pot with drainage holes and simply take out the plant to water it. When finished watering, put the cachepot back into your other container.

Fear of Watering/Overwatering

A common piece of advice you’ll here with succulents is to not overwater them. Unfortunately, this advice usually leads to people watering their plant in sips, which has its own set of issues, which I will explain in a later section. Instead of soil, people are often taught that better drainage is the solution, especially for succulents. The natural reaction then, is to use a sandy mix, to add rocks, or to add a drainage layer. Unfortunately, these are not good solutions. Sand is very fine and will cause water to perch even more. Rocks added to a soil won’t do anything if the soil still contains over 60% its original medium. But perhaps the most interesting one is the drainage layer. Beginner’s guide to watering:
  • Prepare the water by adding a 3-1-2 fertilizer at half the recommended dosage from the container’s instructions.
  • Water until excess comes out the bottom of the pot’s hole(s).
  • Discard the excess water immediately. Avoid letting the plant sit in the water to reabsorb.

PWT Height

The layer of water that forms at the bottom of a pot is called a perched water table, abbreviated PWT. A PWT is the saturation point where capillary action in the soil equals the force of gravity. In other words, at a certain height, water won’t drain anymore. Remember that a particular growing medium has a particular PWT height. The height correlates to the size of the growing medium’s particles. Adding a layer of large rocks underneath organic potting soil actually raises the PWT, reducing the space your plant has to take up air. In other words, it’s as if you’ve just shortened your pot. Crazy, right? If you want to experiment with a PWT and have a plant potted in organic potting soil, you can water it and let the water stop flowing out. Then, with your plant over the sink, lower it slowly and jerk the pot upward. All that excess water that drains out – that’s the PWT. If your plant needs to be potted up, do so carefully or consider repotting it. And unless the roots have noticable issues, do not trim the roots. There is a common misunderstanding that when you repot your plant it should also be trimmed. This is false. Never trim roots unless you find there is something fundamentally wrong with it; plants don’t like their feet being chopped off.

One-Plant-One-Pot Potting

I have also started to do a one-plant-one-pot method, as it allows you to tailor each plant’s water, fertilizer, and light needs. So it’s useful to be able to move individual plants around as the lighting changes. And even something like two identical Haworthias can have slightly different light needs, if one is older or younger. It just gives you more flexibility. ~XO