Soil Matters - Proper Soil Preparation & Information.
Plants have evolved in relation to the soil type they naturally grow in. Therefore, most agaves, cacti, succulents and yuccas are adapted to a loose, well-drained soil. When planting, start by adding a bit of organic matter to your existing soil like peat, aged manure, or compost, then blend in some inorganic material to help improve drainage such as pumice, perlite or volcanic cinders. Pumice is a natural, light-weight rock that is formed deep in the earth when gases are released during solidification of lava. It is a complex, natural process that creates a porous product that can store beneficial water and nutrients in its pores that plant roots can utilize. Even though it is a low-density product it does not readily decompose, making it an ideal amendment for a host of different soil types. Likewise, volcanic cinders can provide a valuable component to soils due to their shape and composition. Inorganic materials also benefit the soil atmosphere by promoting healthy gas exchange withing the soil profile for roots and microorganism populations.
NOTE: For low desert & western soils in general, too much of any added materials to your native soil can yield negative establishment results. Always blend in any amendments well to avoid future soil interface issues, which can occur when the roots reach the pure natural surrounding soil. Woody shrubs and trees can take 12-18 months to become fully established. It is around this time period or slightly later that some plants can start developing nutrient deficiency symptoms. Watch for things like chlorosis, nitrogen or trace element deficiencies. The right fertilizer, elemental amendment or nutrients can help rectify issues, should this occur. We'll discuss fertilizers, nutrients and amendments further in a future blog.
For Potted Plants
Use a fresh, clean potting soil. Quality, or premium potting soils are a perfectly blended mix of organic and inorganic components. They provide excellent water-holding capacity, beneficial nutrients, and excellent drainage. Our premium potting soil is comprised of about 70% compost, 20% perlite/pumice or ground cinders, and 10% aged manure. Of course, this is basic analysis, and we do use our own specific formulated mixes for different types of plants. The yuccas are not in the same formulated mix as the cacti, for example. Lantanas are not grown in the same soil mix as the Euphorbias and so on. We take our soil preparation seriously and so should you. You can order our Premium Potting Soil mix today!
Proper pH
All plants have also evolved to achieve optimal growth within a certain pH range. The pH range, to refresh your memory, is how acidic or alkaline a soil is. 7.0 is neutral, with the lower numbers indicating more acidic soil, and those higher than 7 are more alkaline. An average pH range of 7.5 to 8.5 is ideal for most native agaves, cacti, yuccas and succulents. Most non-native, green leafy plants prefer more organic soils, that are also well-draining but with an average pH range of 6.0 to 6.5. For reference, most average desert soils have a pH range of 7.5 to 8.5.
Remember, the pH scale is logarithmic, based on a unit of 10. Like the Richter scale to measure earthquake severity, that means that a pH of 6.5 is 10 times lower than one with 7.5 reading. While it is possible to lower the pH of your soil to 10x lower than normal, be aware it will take time, effort and cost to do so. It typically takes 1 year to lower the soil pH by 1 unit, depending on the existing organic matter, microbial populations, moisture, composition, etc. Realistically, even dedicated gardeners barely have time to weed, water, prune, clean, and harvest, much less spend time testing and augmenting soils to achieve a significantly lower pH.
Consider Blueberries for a minute. They are not a common crop you find in arid or semi-arid areas. This is generally not due to the heat, as you might expect, but rather it is a function of soil pH. Blueberries (Vaccinium sp.) require a low soil pH of 4.5 to 5.5 to perform well and produce fruits reliably. Achieving and maintaining a minimum pH of 5 is nearly impossible to sustain in naturally alkaline, non-organic arid region soils.
The important point regarding soil pH is that planting native or non-native but adapted plants, that have evolved with and are adapted to a similar pH range, makes the gardener’s job much easier and more sensible.
Note: Consider having a soil test done first, before you plant. “Don’t guess, do a test”, is the mantra of soil scientists & agronomists. A soil test offers the most accurate information about pH and all the soil characteristics you will need to make proper plant and amendment choices. Call your local county ag extension for a soil testing lab near you.
A Bit about Clay
Heavy clay soils often limit healthy plant growth for cacti, Agaves, succulents as well as other plants, and it can pose serious problems for proper watering. Therefore, amending clay soils is always recommended. To help improve clay soils, amend with organic materials like peat, aged manure, or loose compost. Although it seems counterintuitive, don’t mix in sand, pea gravel, or stones, as these mixed with clay will create adobe or a cement-like material that typically make soil problems worse. Adobe is great for building blocks but not for growing plants in. Peat moss is the best amendment for clay since it decomposes slowly and provides an important fibrous component. When thoroughly blended with clay it helps to naturally separate the tiny, plate-like clay particles allowing for better porosity as well as freeing up nutrients that become immobilized within the clay due to the compact structure and chemical composition.
As always, if you have additional or specific questions about soil matters you are dealing with, don’t hesitate to reach out to us via email. happyvalleyplants@gmail.com
** Blogs & photos by Daniel S. Goodspeed, without use of AI. No photos or blog info may be reprinted or reproduced without permission or consent of the author, Happy Valley Plants™ or its subsidiaries. **
