November 15, 2011

"Soilless" soil ?

a near-perfect soilless mix:
equal parts of peat moss, perlite, vermiculite
Many gardeners have worked with artificial soil mixes, sometimes called "soil-less" soils, which is sort of a misnomer. This implies that "real" soil is organic, of the Earth, and only occurs naturally. For most of us, if it's outside in the yard, it's soil. If, according to my Mother, it's on my shoes when I walk in the house, it's DIRT. Perhaps I can shed some light to the idea of artificial soils, and the topic is no small affair to clarify, since there are so many components and mixtures to choose from. Let's look at the most common components.  

One of the most important things to remember is that artificial soils are usually made to grow plants in pots in greenhouses, where plants need a very stable supply of water, and where the plants are produced in a few months to a year at most. These mixes are not very suitable outdoors in the wettest parts of the year. They are often used in propagation beds and with high-demand plants like annuals, Poinsettias, Chrysanthemums, and many perennial plants in small pots.  

The standard of many Begonia and fern growers

Most of these soilless mixes have a finite life in the pot, since the organic components break down, compact, and rob the root system of air. There are other aspects to using soilless mixes for fast-growing, moisture-loving plants, too. In the time that the mix is functional, the plants can grow well, but the grower must realize that as the plants root into the mix, the pots become full of roots, the mix becomes dense with roots, and the plants can choke themselves to death rather fast. One way to increase the life of a solless mix, and thereby increase the longevity of the plant in the pot, is to remove the organic aspect of a mix, leaving just inorganic materials such as calcined clay, perlite, or pumice in the mix. This has become a trend in many propagation bed procedures, where the mix remains intact, and cuttings are rooted in it after the medium has been sterilized between batches of cuttings.     

Calcined Clay
aka Turface, Profile, Quick Dry

Many Bonsai, Cycad, and aquatic plant growers are using calcined clay as part of their potting mixes, and in some cases, using 100% calcined clay  as the sole medium. The water percolation and subsequent air drainage is excellent. This ingredient also hold fertilizer well. many soilless mixtures hold fertilizer very well, a boon to the grower, but a possible hazard to the plant if the mix dries out, leaving high concentrations of fertilizer left in the mix. It is important in any containerized potting mix to occasionally flush the fertilizer residues out of the pot by repeated heavy waterings. Rainwater or distilled water can be excellent for this purpose. 

Soilless mixes, also called "artificial soil" can be a huge benefit to growers of high-demand plants, but growers and hobbyists need to understand the short-comings of the mixes. Inorganic soils can be used effectively, but as with all soil components, each has its quirks. Caveat emptor.

Craig Morell
Pinecrest Gardens


November 3, 2011

Managing Storm Damage in Your Garden

Hard to recover a tree in this condition,
but possible.
In this section of the country, storms of various sorts assault us now and then. We have tornadoes, hurricanes, tropical storms, downburst cells, and lightning hits. There are several forces at work in the damage these storms can cause, and as a gardeners you should be aware of the suite of problems that can arise.
You should also be aware of what NOT to do, such as "hurricane pruning".

One of the unseen dangers of protracted rainfall is that the soil can become super-saturated, and allow trees to fall over with only moderate wind gusts. This tactic is likened to a spoon in a bowl of Jello; it can move easily in any direction. Since we have such weather problems, I suggest  people keep their trees trimmed in such a way as to allow wind to pass through them easily, but this is not "hurricane pruning". An experienced arborist can remove selected parts of the canopy while maintaining the structural integrity of the tree. Overwatering and over-fertilizing can also lead to a dense canopy of soft wood and soft foliage, prone to breakage in weather events.

This iconic photo shows what can
happen in a hurricane.
This palm would be unfazed
by the damage, but may succumb
to root stress.  

Palms NEVER need "hurricane pruning" ! Palms are designed to withstand even fierce winds, and rarely blow over if they have solid root systems. palms usually have fairly strong root systems, provided they are furnished with enough potassium, and a fairly low nitrogen level. A 12-4-12, 12-4-15 or equivalent type of Palm Special fertilizer is adequate for the needs of most palms. Very high nitrogen products such as most turf fertilizers, will foster a lot of foliage and fewer roots than desired. 

If palms and trees are damaged, tend to broken limbs immediately, using razor sharp tools, and make the cuts as cleanly as possible. In the case of trees, cutting very close to, but not into, the ring of tissue surrounding the base of the branch ( the bark "collar") is good arbor practice. Palm fronds should be cut to the nearest broken part of the frond leaving as much of the frond intact as possible. Where trees and palms can be stood up after a storm, the soil should be watered into place to eliminate air pockets, and the roots should be well watered for several months to allow new roots to form. Expect a recovery time of 3-5 years  after such trauma, and even longer for trees older than 30 years.

A tree will recover from this type
of damage, but will need 7-12 years to
get a solid structure again

One big mistake people make after storms damage their trees is to fertilize them, thinking that the roots will grow faster if there is ample fertility in place. The truth is just the opposite: concentrated fertilizers applied after a major root trauma can burn roots to death, and kill the tree or palm shortly afterward. It is wise to wait 4-6 months after the trauma, and fertilize at 1/2 the normal rate until a full set of new leaves or fronds can be produced. In the cases of old palms and trees, they make not recover fully for 7-10 years, so monitor them carefully, looking for the rate at which new fronds or leaves are produced, versus those which drop off. If the new vs old ratio is better than  1:1, you're on the right track.

The main messages to remember about recovering trees and palms after a major weather problem are to treat them carefully, removing drought stress, making sure they are secured in the ground until they-re-root, and fertilizing them gently until full recovery is attained. Damage can come from even modest storms, which can have violent, very localized damage, sometimes affecting one tree in the middle of a group. There are many ways storms can damage a garden, from rain, wind, lightning, flying object debris, and so on. Lightning is one of the most dangerous, since it arrives without warning, and of unknown strength. It can be accompanied by supernatural wind bursts, sometimes called downburst cells, which can squash a 400 ton jetliner to the ground like a bug.    

Lightning strike on
Queen Palm group

Lightning can kill one palm in a grove, but the "side shocks" from the strike can kill plants up to 50 feet away. Downburst wind cells can fell an entire group of trees in a counter-rotating pinwheel arrangement, defying any law of reason. You can't prevent the damage, but you can become educated about repairing your garden's primary residents. 

Craig Morell
Pinecrest Gardens