Dry Cycle

[Leelanau Palms]

I've seen mention in passing in our forums of a "dry cycle" in managing the irrigation of (certain) palms in pots and in the ground. Could y'all please explain what this means, why it might be important, and to which common palms it applies? Some specific palms I wonder about include: beccariophoenix alfredii, jubaea chilensis, and butia odorata. Thanks!

[Harry’s Palms]

My Butia gets a steady supply of water all year here in Southern California . The other varieties , I have no experience. Harry

[sonoranfans]

The dry cycle": is the time interval between wetting of the soil and when it dries enough to admit the necessary(depending on species) oxygen into the soil volume containing the root mass.  Oxygen inhibits growth of some harmful microbes and feeds the beneficial soil microbes while stabilizing conditions for the plant to defend its roots from pathogens.  Fungi grow notably faster at coolish temperatures so the cool season is when you don't want constantly wet soil.   A soil that is too dry will inhibit nutrient takeup and desiccate the plant and possibly kill it.  A soil that is continually wet will limit root growth (especially to depth) which will be reflected in reduced above ground growth. 

Dry cycle vs soil depth:  Now that you have considered the overall view of the dry cycle, consider it as a function of soil depth.  It should be obvious that due to drainage the bottom of the pot has a longer dry cycle than the top.  This tells me to put more moisture holding material at a more shallow depth and to use a top cover mulch.  This approach will put the dry cycle closer to equivalence vs depth.  Faster draining soil has a more consistent dry cycle at different depths so its easier to hit that ideal dry cycle for maximum root growth.    For potted palms its a little different as the water can only drain through the holes in the bottom of the pot while a planted palm the water can drain in any direction below the soil. 

Now having said all that some species are adapted to almost constant water contact.  The immune system of the roots is highly functional in wet stagnant soil.  Other species the root will get fungal rot and die back.  The palm doesnt die but the roots are shrunken into the dry cycle zone that supports the moisture cycle they are adapted to.  It makes some sense that palms and plants that grow deep roots will be some of the more sensitive to constant wetness

 

Soil moisture probes can be used to evaluate the moisture at depth.  I recommend a 2" PVC pipe to 18" is put into the soil and the inside of the pipe should be empty so you can insert a soil probe periodically, or you can rig something to take a soil sample at depth and examine its moisture.  

Soil ammendment should be to try to make the dry cycle more uniform with soil depth so irrigation does not wet things down before the depth had dry cycled.  Interestingly mulching in top in sandy soil keeps the top of the soil moist longer so it effects a more uniform dry cycle with the deeper soil.  A rich mulch at depth does the opposite, it exacerbates the soil depth dry cycle uniformity.

Pots as I pointed out above will have a big difference in dry cycle top to bottom of the soil if the soil is uniform and especially if it is heavy..  For this reason I tend to put a heavier perlite mix in the depth for drainage and more organics at a shallower depth.  And remember with potted plants, you may need to heavily flush them every few months as salts from irrigation water and fertilizer can accumulate in the potting soil.

Nutrients in soil  Nutrients in soil near roots is taken up and tjheir concentrations drop to low levels.  More fertilizer is transported to the roots in the next wetting cycle.  IF the ground has not drained, the penetration of nutrients will be slower into the root zone.  This will happen to all palms, and it is good if you can wash away the old waste products from fertilization.  This will work much better with a dry cycle as the(new) water will move more completely through the dry soil than the wet soil.

 

Yeah its more than you wanted I think, but knowing what the dry cycle is doesn't tell you why its important. 

[Leelanau Palms]

Thanks for the information. Can anyone comment on the specifics of how the dry cycle applies to the palms I mentioned?

[flplantguy]

Im wondering about Beccariophoenix too, i have a one gallon in the ground adjusting in sand i water daily and question if its the right amount.

[Jim in Los Altos]

All of the 130 species of palms (300+ palms) in my garden get pretty much the same watering regardless of time of year. Many are drought tolerant species but love the constant water supply. Some winters are so wet that there is virtually no dry cycle for weeks on end. I must say though that my soil drains well and that can make the difference. 

[flplantguy]

Mine also drains well and i love to water lol. That sounds like i will be ok.

[Merlyn]

On 6/4/2024 at 10:43 AM, Leelanau Palms said:

Some specific palms I wonder about include: beccariophoenix alfredii, jubaea chilensis, and butia odorata. Thanks!

I have Alfredii seedlings up to 20-25 footers, and the only thing they dislike is going completely dry as seedlings.  I lost quite a few because one sprayer-on-a-stick got clogged and they went without water for a couple of weeks in a hot May drought.  Butia will also die in a pot if hou let them go completely dry for a long period, say several weeks.  But they are also very tolerant.  I have no experience with Jubaea, because they hate the FL constant swampy heat.  They are desert palms, so can probably go a long time on little water, once established in a pot.

In pots you need to just balance the water retention of the soil with how much you water them.  My nursery area gets drenched every morning in the summer, and every other day in the winter.  I mix my potting soil at least 50% inorganic with stuff like perlite or Turface MVP, so it drains really fast.

[Leelanau Palms]

6 minutes ago, Merlyn said:

I have Alfredii seedlings up to 20-25 footers, and the only thing they dislike is going completely dry as seedlings.  I lost quite a few because one sprayer-on-a-stick got clogged and they went without water for a couple of weeks in a hot May drought.  Butia will also die in a pot if hou let them go completely dry for a long period, say several weeks.  But they are also very tolerant.  I have no experience with Jubaea, because they hate the FL constant swampy heat.  They are desert palms, so can probably go a long time on little water, once established in a pot.

In pots you need to just balance the water retention of the soil with how much you water them.  My nursery area gets drenched every morning in the summer, and every other day in the winter.  I mix my potting soil at least 50% inorganic with stuff like perlite or Turface MVP, so it drains really fast.

Thanks for sharing these insights. Very helpful