WORKSHOP ON SOIL

David W. Minks

The purpose of this article is to review the Workshop on Soil given at Balboa Park on September 18, 1999.  Please, this is simply a primer on soil, a starting point for the uninitiated member wondering just how to start. 

You are lucky, you get the benefit of my flops.  I was raised in Indiana where garden soil was good if it was black and rich in organic material, with fine water-holding matter keeping the soil moist for the typical week between rains.  When I first started my interest in palms, I read the March 1997 “Palm Journal” article on soils and a few others but I really didn’t embrace it.  You see, I had a mindset of a method that was OK for garden crops, but unsatisfactory for palms.  Probably 125 plants were lost before I started to consider what the experienced palm growers were telling me.  In the summer I lost more than half of my seedlings (liners).  In the winter I lost 5 gallon, large plants in my heavy soil.  At the end of this little expose’ you should be able to point out what I did wrong, and avoid these problems yourself.  A lot of it has to do with the Soil.

What are the Functions of Soil?

1. Hydration.  Water to the root system.

2. Aeration.  Air to the root system.

3. Nutrition.  Food to the root system.

4. Support.  Substrate for root stability.

5. Biological Activities.  Certain bacteria, fungi that are beneficial to the plant.

Implicit in the word hydration is that the palm must have good drainage.  {We all need water but we don’t want to drown in it.}  So the soil must have ingredients that allow the water to drain away.  Incredibly, if you give the plant too much organic material (gee, I’m satisfying the nutrition function) you generally have soil that doesn’t drain well. But it turns out that many palms can thrive on the most retched, non-organic soil, like ‘DG’ (decomposed granite).  So, there is a balance that must be struck, especially for the tender, immature plant—it prefers drainage over rich dirt.

Another implicit item.  It makes no sense to take a tender seedling, shake all of the moist dirt from its roots then pot it up into a gallon container with dry soil, and water it afterwards (even soon afterwards).  Your claim is:  I watered it, the hydration function is satisfied!  No, the dry soil pulled the moisture from the roots and that isn’t good.  {If I run quickly through the desert, when I get to the ocean I’ll have all the water I want.  No, you will die in the desert when the moisture is pulled from you.}  So, moisten the soil for an hour or so before you use it to pot up seedlings.  Simple as that.

Does the mix really matter?  Yes, if you want a healthy plant requiring minimal attention.  Other methods exist where soil isn’t even used but they require too much time and money. 

1.      You’ll find that temperature and humidity differences between the coast and inland call for a different mix.  If you use a mix with fine silt on the coast, the soil will remain wet too long and the roots may rot.  Similarly, if you use a light mix inland, you may have to water 4 times a day to keep it from drying out.  Everyone experiences the sadness of forgetting to water a seedling just 1 day and discovering a crisp wisp the next day.

2.      A greenhouse is warm and humid, the indoors of a house is warm and dry, a shade house can be very hot and dry. Each of these conditions will require some thought about your mix. 

3.      The types of palms can influence the mix needed.  The Butia capitata does well with a very heavy mix.  Many Dypsis sp. demand a very light mix.

OK, I confess.  There is no Miracle Soil!  But let me throw out a few recipes for you to try.  Square brackets indicate what this ingredient does, the parenthesis indicates the function served.

Eddie Green’s Mix #1 (for containers up to 15 gallon)

1/5 coarse sand [a fixed spacer, some air, but packs tightly](S,A)

1/5 peat moss [fine decayed plant material, organic] (H,N)

1/5 bark  [wood, with shape, breaks down gradually, organic] (A,N,H)

1/5 pumice  [fixed spacer with larger air pockets] (S,A)

1/5 humus  [composted plant material, organic] (N,H)

Phil Bergman’s Mix (for containers to 5 gallons; add in a little soil for larger containers)

10        top soil amended

15        pumice #2

15        1/8” or smaller Pine Bark

15               nitolized redwood shavings

20               perlite #2

10               coarse washed sand #12

15               coarse peat moss, shredded

dolamite, 1 lb per cubic yard

osmocote, 1 lb per cubic yard

A-1 Soils Nursery Palm Mix (for 1-5 gallon containers, (858) 549-1041

25% peat moss

35% Douglas fir bark, nitrolized

15% Lifelike™ (contains some soil with chicken manure, organic)

25% washed coarse sand

Notice that there are varying proportions but you will see sand, peat and bark with other organic material to provide structure, nutrition, hydration and aeration.  Sand appears to be a universally used component of soil.

Fine Tuning the Mix

Check your new soil mix with plants daily and decide if you need to:

1.      “Open it up”.  Perlite, pumice are increased relative to the other items.

2.      “Close it up”.  Sand, humus, topsoil are increased relative to the others.

Smaller plants need soil that has been opened up, the larger plants prefer soil that has been closed up.

How will I know?… when the plant in my soil needs watering, has problems? 

Open your eyes, look at the soil each day.  Look at the top inch of the soil, if the color has changed to a lighter shade then the plant may be drying out and needing water. Stick your finger along the outer edge of soil, inner edge of pot; if dry then time to water.  Lift the pot; if it has become lighter then time to water.  If the soil smells moldy or has a pigpen smell; the roots may be rotting, change the soil.  If the plant is drooping, faded, spotted or otherwise looking poorly; check the roots for snails, ants, rot or other undesirables.

What is the life of Soil in a container?

About 2 years.  Organic materials break down and become silty, thus the mix drains slowly.  Also, you may be unaware that the soil is washing away next to the root structure thus the roots are being exposed to air.

Plant Saver Hints:

1.      When you get a new palm from a grower, always repot it using your own mix.  You know your mix well and the time required between waterings, thus uniformity will improve.

2.      Store soil in bags or trash cans.  Keep this soil moist.  Did you know that peat moss, once allowed to dry, repels water?  Experienced growers water their container plants 2-3 times within a 20 minute period to insure that the mix is thoroughly wetted.

3.      Don’t reuse old, previously used, soil.  Soil can contain diseases that may spread.

pH and Micronutrients

Use lime to neutralize the acid of peat moss, humus or bark.  Use 20-20-20 liquid fertilizer like Gro-Mor™, or a slow release fertilizer like Apex™ Palm fertilizer, both have trace minerals and micronutrients, but the slow release fertilizer is unlikely to burn your plant.  Use Vim™ or Micromax™ or topsoil (sparingly) for trace minerals and micronutrients.  As an example of trace elements added, A-1 Soils uses 2 parts Dolamite (lime), 1.5 parts Nitroform, 0.5 part pot. Nitrate, 1 part Triple Sulfate, 0.5 Iron Sulfate, and 0.75 Micromax™ for their Nursery Palm Mix.

References for this Workshop:

1.      ‘Palm Journal’, PSSC, March 1997, soil article by all the PSSC stars.  Much of this workshop material started in this article and was copied wholesale, thanks for this understanding.  Read this article yourself and learn about the experiences of these authors first hand.

2.      ‘Palms’, (formerly ‘Principes’, IPS), April 1999

3.      Kent Houser, during our massive Dypsis sp. potting up sessions

4.      Phil Bergman, advice and use of his famous mix