How to Fertilize Cycads, Part 2

The first part of this article discussed the problems that alkaline (high pH) soil and water present for growing cycads and other plants.  In this concluding portion, we'll address the specific nutritional needs of cycads, and how to solve the problem of alkaline soils and waters, while feeding your soil to grow healthy cycads and other plants.

Cycad Nutrient Needs

In addition to the first two concerns we've mentioned, alkaline soils and alkaline water, the third concern is Cycad-specific fertilizer needs.  In his fundamentally important article, Tom Broome pointed out that fertilizing is an important tool to augment cycad growth and coning. His research has revealed that cycads benefit from higher nitrogen, particularly soluble nitrogen, to provide the strength necessary to push forth large flushes of leaves and produce strong and viable cones. Tom points out that while cycads may look like palms, they have different fertilizer needs, writing:

I find many people using palm fertilizer on cycads. They think because cycads look like palms, they are closely related. Of the seed bearing plants, cycads are about the farthest plant group away from palms. Most palm fertilizers are low in nitrogen (with N around 7-10). To produce a high enough energy level so that previously mentioned results can be attained a fertilizer with a (higher) nitrogen level … needs to be used.

Also, it is well-documented by Tom and other cycad growers that micronutrients are necessary for healthy cycad growth.  This is something palms and cycads do have in common.

                       

Additionally, most cycads prefer a slightly acidic soil. This is opposite from what arid climates and an alkaline water supply offer.

The Solution: A Fertilizer that Addresses Soil and Water Alkalinity and Meets Cycads’ Nutritional Needs

Ultimately the fertilizer you’ll want to use on your cycads will combine nutrients from organic and chemical sources to accomplish the following:

1. Address soil and water alkalinity, both short-term and long-term, through a combination of organic and chemical sources that not only feed the plant, they also feed the soil
2. Add the necessary iron which cycads need but is absent or unavailable in most soils
3. Add organic material for the soil’s and plants’ long-term health
4. Provide a combination of nitrogen sources, organic and chemical, soluble and insoluble, to give the plant its necessary fuel for growth and also feed the soil
5. Combine chelated and non-chelated minerals for optimal nutrition

Finally, regarding when to fertilize, here is another graph from the Western Fertilizer Handbook:

If you fertilize when it’s cold outside, nitrogen takes much longer to get to your plants, and may have dissipated by the time the soil is warm enough to feed your plant(s). Weather should be warm when your cycads start pushing forth their new leaves. So, you should wait until outside temperatures average in the 70’s for a couple of weeks before you apply fertilizer in early spring. Then, apply fertilizer again in early summer, and perhaps once more in late summer just before fall.

I wish you the best growing success, and please contact us at the nursery if you have any questions regarding this information.

For information on recommended cycad fertilizers, as well as a printable version of this article, please visit http://www.cycadpalm.com/howtofecy.html

***Thank you to Glen Williams, whose contributions have augmented the information in this two part article, and have made it more clear and readable.***

Sources for this article include:
North Carolina Department of Agriculture & Consumer Services
Western Fertilizer Handbook
Seattle Public Utilities
Illinois Department of Public Health
Florida Water Resources Journal

How to Fertilize Cycads, Part 1

Cycads have become increasingly popular garden plants in recent years. In addition to the more common Sago Palm (Cycas revoluta), rarer species of Cycas, and cycads like Encephalartos and Dioon are finding their way into upscale landscapes.  Cycads’ increased popularity is due to several factors, including their distinctive look, their drought-tolerance, the intrigue of owning a “living fossil”, and that when given proper care, cycads are stunning landscape features. This article addresses the last factor, proper care, specifically how fertilizing can promote healthy and attractive cycad growth.

To be attractive landscape features, cycads need fertilizer to achieve their best healthy growth. Fertilizing means amending your soil by adding nutrients, necessary elements not sufficiently present in your soil.

The Western Fertilizer Handbook shows 16 Essential Elements for healthy plants in this chart: 

        

·  H – Hydrogen ·  B – Boron ·  C – Carbon ·  N – Nitrogen ·  O – Oxygen ·  Mg – Magnesium ·  P – Phosphorus ·  S – Sulphur

·  Cl – Chlorine ·  K – Potassium ·  Ca – Calcium ·  Mn – Manganese ·  F – Iron ·  Cu – Copper ·  Zn – Zinc ·  Mo - Molybdenum

Plants generally obtain sufficient hydrogen, oxygen, and carbon (as carbon dioxide) from air,  water and sunlight. The remaining necessary plant nutrients come from the soil. Primary nutrients plants need are nitrogen, phosphorous, and potassium. Smaller amounts of calcium, magnesium, iron, and sulfur are also necessary. Finally, even smaller amounts of such micronutrients as copper, manganese, zinc, boron and molybdenum can be important. If your soil and water does not have the above elements in sufficient quantity, you need to add them, amending your plant’s “diet”.

During the past 15 years, we have evaluated numerous fertilizers in our nursery and in clients’ gardens to find the best way to augment healthy cycad growth. Through trial, error, reading, and seeing good results and bad ones, we’ve discovered there are several ways to amend soil to grow healthy cycads.

Before discussing a solution, which I will address in the second part of this article, it may be helpful to address the challenges growers face which led us to come up with some specific ways to improve cycad growth:

1. Alkaline soil, found throughout the country, presents plant growing challenges
2. Alkaline water distributed by major utilities in the USA creates additional challenges
3. Cycads have special nutritional needs different from those of other plants

Alkaline Soil and Waters

The pH scale measures acidity and alkalinity. It ranges from 1 (highly acidic) to 14 (highly alkaline), with 7 being neutral. An increase or decrease of one point equals a multiple of 10, so an 8 pH is ten times the alkalinity of a 7 pH. Rain water pH is slightly acidic, generally ranging from 5.5-6.0. Most garden plants prefer a pH of 5.5 to 7.

Arid regions tend to have soil higher in alkalinity and salts, and lower in iron and organic material.  This is a problem for many ornamental plants. Highly organic content generally results in a healthy living soil that can grow strong, pest-resistant plants. Highly organic soil usually results in soil with a slightly acidic-to-neutral pH. Arid climate soils, without organic or other amendments, typically range from 7.5-8.5 pH.

Alkaline tap water is predominant throughout the USA. Many water utilities add elements to increase water alkalinity because this reduces water’s corrosiveness, heavy metal leaching, “red” water and nitrification. For example, tap water in Los Angeles ranges from 8.0 to 8.5 pH, according to the LA Department of Water and Power.

As you’ll see in the graph below from the Western Fertilizer Handbook, nitrification, the conversion of Nitrogen in soil into a form that feeds a plant, is best at 5.0-7.0 pH.

Following this graph, to use fertilizer effectively (and economically), you want to grow plants in soil from 5 to 7 pH.  If you’re not acidifying or neutralizing your water, and your soil remains as is, alkaline water and soils can prevent Nitrogen from being processed by your soil for your plant’s use.

This Western Fertilizer Handbook graph shows what pH does to nutrients’ availability:

A high pH (alkalinity) reduces key nutrients’ availability, and delays or reduces soil nitrification. Plus, water utilities’ reduction of tap water’s iron and nitrates, beneficial for other reasons, means fewer necessary plant nutrients.

Note that iron (Fe) is less available in alkaline soils (above 8.0 pH). And though color is not always a good indicator of a soil’s fertility, African cycad habitat photos show dark orange/reddish-brown soil, indicating high iron.  Cycads love iron, and arid climate soils and municipal water tend to be iron deficient. When cycads grow well in places like Hawaii, it’s not only that they’re in the tropics, but also that volcanic soil is iron rich.  Look at the “Red Dirt” they’re growing in! Growers in Hawaii and South Africa often scoop ground soil and use it in potting mix (see photos below).

One way to offset deficient organic material deficiency in alkaline soils is to use organic mulch, and organic elements in your fertilizer for all plants, not just cycads.  This helps neutralize soil pH, and feeds your soil, so the soil can feed your plants naturally. Organic mulch also moderates soil temperatures, lowers water loss from the soil, and encourages beneficial microorganisms that help plants grow.

Our next posting will conclude this article by discussing cycads' specific nutritional needs and how fertilizer can address these needs and deal with alkaline soils and waters.

Protecting Cycads and Other Plants from Frost

We had a cold weather snap this past weekend in California and the extended Southwest threatened the cycads and succulents we grow.  It was projected to be our worst cold spell since 2007 when many plant growers, both home and commercial, lost leaves and plants. Parts of Los Angeles and surrounding areas got below freezing, and we had snow in parts of Southern California as low as 500-1000 feet.  We had a hail shower at the house, but it missed our nursery.
 If you have outdoor plants like us, here are some basic steps to take before a potential frost and after:

1. Cover tender plants with frost cloth. Hopefully it hasn't sold out everywhere at this point. Check your local nursery or garden supply store for availability. Using an old sheet is better than nothing, but frost cloth is preferable.
2. Most plants could benefit from a small watering as part of your preparation, but NOT cactus and other water-retaining succulents. As you know, water expands when it freezes. If the cells of your succulents are full of water, they will burst when the water freezes, killing the plant. If they're a little low on water when the cold arrives, there's a chance the cell walls will be able to stand a little expansion and won't burst.
3. Bring inside as many of your container plants as possible. If they don't fit inside, placing them against an outside wall of your house or apartment, particularly if there's an overhang, can make a big difference. We brought several species into our greenhouses which normally remain outside, such as some of the central African encephalartos (Encephalartos kisambo, Encephalartos gratus and Encephalartos manikensis), tree dioons (Dioon spinulosum, Dioon mejiae and Dioon rzedowskii), subtropical zamia like Zamia furfuracea, and a couple of Ceratozamia species. We also brought in recently potted aloe and aeonium succulents.
4. Mulches can protect your plants by moderating root temperatures and preserving unfrozen moisture. By protecting the caudex and roots, they have the effect of a blanket, in terms of relative warmth.
5. Here are some additional tips on How To Grow Cold-Tolerant Plants via a slide show on our website: http://www.cycadpalm.com/howtogrcocyi.html

What should you do after a freeze?

1. Be patient. The cold spell in January 2007 was tough on plants, but more made it through than we originally thought. Although we found that many plants had experienced leaf damage, the roots of these plants had survived, and in the spring and summer, fewer than 25% of plants suffering leaf damage had not recovered. By late summer, the number went down to 10%. We lost some plants, but not nearly as many as it looked right after the freeze.
2. Do not prune or cut back plants too hastily. In case of another cold spell, an unpruned plant helps provide insulation for its roots and main trunk. Also, pruning too early could force the plant into growth, which would stress the plant and force it to use of more of its reserves, leaving it vulnerable to weather and pests.
3. Wait for new growth on woody plants to actually know what's dead.
4. Water only if dry. If roots are damaged, over-watering now can encourage root injury.

Please Note: It may take several months for new growth to appear. 


Also, please consider keeping notes on the damage that occurred for your own reference, and the benefit of others.