This is the second of two blog posts that are being published to showcase an article that was written by myself and another palm lover; the article was intended for the Palm Society of Southern California’s quarterly journal. As I stated in the first post, an unscrupulous treasurer robbed the PSSC coffers and left them broke. So the journal is on hold for a while. Rather than sit on this article, I decided to use my blog to get the information out there, as it could prove valuable to others in helping preserve this exceedingly rare palm before it is too late.

Click the link to read the first post: “The de-lidding of Clinosperma macrocarpa seed“.

The article continued:

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By June of 2012, most of the ten germinated Clinosperma macrocarpa seed had a spear and some good-sized roots showing, so it was time to meet back up to exchange and start the next challenging stage with these NewCals. This next stage involves getting them past the “seed to soil” part of their development without them damping off. Having grown a vast amount of New Caledonian palms from seed, I can say the most difficult stage in growth is when a plant has exhausted all nutrients from the seed and moves to getting all nutrition from the soil. It is during this transition and a while after that they love to dampen off.

For the majority of us not blessed to live in a tropical paradise like Hawaii or Queensland Australia, we must put forth far greater effort to grow tropical and subtropical plants. Here in Southern California we have unique challenges like winters that can bring freezes, Santa Ana winds that blow in single-digit humidity, a large photoperiod disparity throughout the year, or the constant abuse from poor tap water quality. As Matt pointed out in the first post, I have gone through many failures to get to a point where I believe I have the best possibility to grow these Clinosperma macrocarpa seedlings in Southern California. There are four factors I mainly focused on:

1) Proper Humidity

2) Planting Mix Quality

3) Proper Nutrition

4) Good Water Quality

Humidity

To me, humidity is the single most important factor in growing New Caledonian palms from seed. I have run a few different experiments with humidity, and in every case those seedlings grown in a humid environment out-grew or out-survived those not grown in a managed humid environment. The least expensive and best way I have found to keep the humidity up is to use the plastic hot houses you can get at most garden centers. I potted the Clinosperma macrocarpa seedlings into small bands so I could easily organize a bunch of plants into the hothouses to ensure humidity stays above 70%. That is actually very high when you consider my greenhouse can see humidity levels as low as 7% during Santa Ana events. Running misters is no longer an option, as I find they create the perfect environment for fungus and pests to proliferate.

Once the seedlings outgrow the small hothouse, they are potted up into 2.5-liter Stuewe treepots. They are then moved into a larger plastic hothouse, stored within my actual greenhouse. They will stay in this hothouse/greenhouse until I am about six months out from planting them in my garden. This gives me plenty of time to slowly acclimate them from their high humidity environment without putting them into shock.

Planting Mix

My goal was to create a medium that is neutral in pH, holds moisture, but drains quickly. You never want a mix that breaks down rapidly and gets mushy (especially when dealing with slow-growing palms that will be in that mix longer than quicker-growing palms). And you never want a mix that dries out too quickly. The palm mix I make is not cheap, but I figure why cut corners now. Part of the mix idea I got from a now deceased palm nut and friend, Tri Tvoung. When looking for a great mix years back, he went to the one place where people really take growing plants serious: a marijuana-growing supply store. That visit resulted in the use of Fox Farms products as the key element in the blend. It called for an equal parts mix of Light Warrior with Ocean Forest. This mix alone was good, but I found it to be still a little too thick for a greenhouse in SoCal. I started adding EB Stones Cactus Mix in at another 1:1:1 ratio. Doing this also improved growth results and lessened damping off. For more information on this soil blend, you can read a post I did on it here.

While I like to grow most of my New Caledonian palms from seed, I also like to order plants from Jeff Marcus at Floribunda Palms. I noticed that if I left plants in Jeff Marcus’s mix, which was loaded with volcanic cinder, the plants wouldn’t damp off at the same rate as moving to other mixes; as such, I decided to cut the mix described above further by adding imported volcanic cinder at about 25% cinder to 75% mix. With each addition I made to the original Fox Farm blend I noticed an improvement in plant health and a decrease in damping off. I am finally at a stage where I believe I have a great mix from which to grow Clinosperma macrocarpa (or most other palm seedlings, for that matter).

Nutrition

A year prior to growing Clinosperma macrocarpa, I installed a Dosatron to help fertigate all my plants in the greenhouse. The ability to apply a guaranteed ratio of fertilizer and continue to do so with each watering really turned out to be a game changer with my greenhouse culture. I chose to run a 3:1:3 ratio water-soluble fertilizer to ensure I had a high level of potassium coupled with a low level of phosphorus. I would never recommend a 1:1:1 ratio like 20-20-20. Both Growmore and Peters make great 15-5-15 water-soluble formulas that are loaded with micronutrients. I have my Dosatron set to deliver 1 part fertilizer to 300 parts water. So the dosing is very low at .3% fertilizer.

To go along with my liquid fertilizing regiment I also hand water over the palms with Maxicrop Liquid Seaweed every four weeks. Maxicrop seaweed contains over 70 minerals, micronutrients, amino acids and vitamins. I love kelp extract, and seedlings to which I have given a seaweed supplement have always grown into larger, heavier palms with a much more vigorous root system.

I also use Great White to provide a mycorrhizal inoculant. Great White contains 15 different species of mycorrhizal fungi, 11 different species of beneficial bacteria, and 2 species of trichoderma—all in one product. I water in Great White every eight weeks. I have found that palms given Great White end up having a healthier root system than those without when I pot them up over. Depending on the type of plant, it can be a quite a substantial difference.

Here is what a six-month-old Clinosperma macrocarpa seedling looks like.

Water Quality

It is no secret that the water found in Southern California is hard and high in TDS (Total Dissolved Solids). On average, I would say I get TDS readings of 375 PPM with my Hanna Instruments pH, EC/TDS tester. While New Caledonian palms are not as fussy about TDS as, say, some Chamaedoreas, I still believed it to be an added stressor which I wanted to remove. The only option to get all the TDS out of your city water is to use reverse osmosis. A few years back a palm grower was going out of business and was selling his RO system, which I ended up purchasing for a fraction of the price of a new one. After installing the RO system, heavy brown tipping on plants virtually disappeared in my greenhouse.

Those are the four factors I truly believe you must focus on to increase survivability of Clinosperma macrocarpa seedlings. You will find that if you can provide a similar growing environment for your New Caledonian seedlings, you will not have a need for preventative fungicide treatments. I stopped regularly using Subdue a few years ago once the overall health of my plants increased from proper cultivation techniques. You will never keep fungus out of the greenhouse, so the goal must be to grow healthier plants that can resist attack rather than applying regular fungicide treatments.

Of the ten germinated seeds Matt and I started with, one rotted a week after removing it from the canning jar, leaving us nine to grow. Over the course of the next two years we lost the three runts of the litter and are now left with six palms that are ready to be planted outside once we gather our courage. When you consider I once germinated 100 Kentiopsis piersoniorum seeds and only have 15 plants remaining, or that at one stage I had 55 Basselinia moorei seedlings that all ended up dying, then you can imagine I would find a survivability of 6 out 10 a huge success.

Here is how the largest seedling looked as of June 2014.

One Clinosperma macrocarpa seedling even opens a reddish-colored new leaf. It will be interesting to see how this develops over time.

In closing, I found Clinosperma macrocarpa to be, surprisingly, one of the easier New Caledonian seedlings to grow. The plant world rarely offers us this opportunity to have such a rare plant not be as challenging as one would expect. So while not as painless to grow as most Chambeyronias or Burretiokentias, they are definitely much less demanding than most of the Basselinias or other species of Clinospermas. This bodes well for their long-term survival in cultivation.

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That concluded the content that was to be used in the PSSC journal article.

Tagged: Germination, Greenhouse, New Caledonia, Propagation

September 24, 2014