Adonidia merrillii

Focus on insects and fertilizer in order to be successful with Adonidia palms.  Like most palms proper potassium and magnesium fertilization is important for maintaining the maximum number of nice looking leaves in the canopy.  On the insect front, mealy bugs, scale, and mites will be the biggest problems.  Disease would be the last issue considered if the first two problems can be reasonably eliminated.

Light:

    Adonidia palms make great interior palms, but there use should be restricted to interior environments with 500 foot candles or better (Tropical Foliage Plants, Lynn P. Griffith Jr).  An adonidia should do well in any environment that can support a Ficus lyrata, Schefflera 'Amate', Ficus 'Alli', or roebelenii.

Water:

Water requirements are nothing out of the ordinary for Adonidia palms.  When an Adonidia is water stressed, the oldest fronds will lose turgidity and bend downward at the spot where the petiole meets the stem.  Watch for this situation and correct with the addition of water.  This condition can also indicate a high soluble salt level usually associated with fertilizer additions.  A clear water leach can correct the salt level.  Adonidia palms produce heavy roots that make it nearly impossible to penetrate the root ball with a soil probe.  For this reason, use a soil wetting agent as a preventative measure in any watering plan.

Nutrition:

    Larger interior palms may come from different backgrounds which will affect an interior fertilizer program.  For example, an Adonidia produced in a marl field in Homestead, FL will have different nutrient requirements than a pot produced Adonidia that has only a peat based soil-less media in the pot.  These both will be different from a palm produced in more acidic or sandy soils.  Native soils make up a large percentage of the media in the pot and have distinct characteristics.  The best advise would be to ask the grower about the soil in the pot and get some recommendations specific to the palm. In general, Adonidia with marl in the pot, have an ample source of calcium leading to  magnesium and potassium deficiencies due to the competition for cation exchange sites between calcium, magnesium and potassium in the soil.  The pH does not need to be managed.  Alternatively, soil-less media and sandy or acidic soils require pH management with dolomite, and need to be supplied a fertilizer balanced for palms.  A fertilizer with a 2:1:2 ration with about half as much magnesium as potassium is a good starting point.  Too much fertilizer may result in burnt tips.  As a rule, create a repeatable fertilizer program and make small changes over time to dial in the perfect treatment.  It should be noted that palms move some nutrients from older leaves to newer leaves before dropping the oldest leaves.  Premature pruning prevents the recycling of nutrients and requires them to be added manually.  If too many older leaves are bad looking, address this problem with a better fertilizer program and try to keep pruning of older fronds to a minimum.

Insects and Mites:

    Mites, mealybugs and scale are common pests of Adonidia.  All three can be found under the fronds and almost always on the oldest fronds exclusively.  We have seen scale buildups hidden within the newly emerging leaves where the canopy is tighter, but this is very infrequent.  Mealybugs can often be found under the old crown shaft as the shaft starts to loosen in preparation for natural senescence.  For treatment see the Insects and Mites section in the general information section below.

Rhapis excelsa

Rhapis palms can handle a lower light environment than most other interior palms.  Mealybugs and mites are the major problems to watch out for when looking for insects.  These palms do not need much in the way of water or special nutrients making Rhapis palms an great interior plant.

Light:

Rhapis palms will tolerate light levels in the 75-100 foot candles range, but they will be better at 250-300 foot candles (Lynn P. Griffith, Tropical Foliage Plants, 2006).

Water:

Rhapis palms are not heavy water users and can show signs of iron deficiency as interveinal chlorosis if kept too wet for too long.  Rhapis grow suckers that start under the soil.  This activity seems to keep the soil loose and may cause channeling and loss of soil.  Soil wetting agents should be used periodically to manage the dry spots or channels that may form through the root zone.  When a Rhapis is too dry, the leaves will be dull green and slightly shriveled, and the stems will droop.  Try to determine the point just before these signs appear and water then.

Nutrition:

    Low rate slow release fertilizer applications with additions of iron and dolomite will keep the Rhapis looking it's best.  Use a 2:1:2 ratio 6 month slow release fertilizer once or twice per year depending on how much growth potential is provided by the plant's environment.  Find a complete fertilizer with 14-16% Nitrogen and use 8 - 12 grams per gallon of pot volume.  8 grams is for the low growth environment and 12 grams is for the high growth environment.  For comparison, in the nursery, under optimal conditions, 17 grams per gallon of pot volume using a 16% nitrogen fertilizer works well.   Apply dolomite at the rate of 1 tablespoon per gallon of pot volume once or twice per year along with the fertilizer.  If light colored new growth with some interveinal chlorosis is present, drench or topdress with iron.  Use less than the low recommended rate for interior-scapes since most rates are specified for nursery environments. It should be noted that palms move some nutrients from older leaves to newer leaves before dropping the oldest leaves.  Premature pruning prevents the recycling of nutrients and requires them to be added manually.  If too many older leaves are bad looking, address this problem with a better fertilizer program and try to keep pruning of older fronds to a minimum.

Insects and Mites:

     Mites, mealybugs and scale can be a problem on Rhapis.  In the nursery, we see mealybugs the most, followed by mites.  Very rarely have we encountered scale on Rhapis.  Mealybugs inhabit the area where the new leaves emerge from the stem and they can be well hidden in this area.  Look for any sign of white mealybug residue around this are for indication that mealybugs are present.  As the infestation worsens, the mealybugs can be found under the leaves as well. For treatment see the Insects and Mites section in the general information section below.

Phoenix roebelenii

Light:

Roebelenii palms will tolerate light levels down to 300 foot candles range, (Lynn P. Griffith, Tropical Foliage Plants, 2006). 

Water:

     Water requirements are slightly higher for roebelenii palms than for other palms.   Watch for the droop of older fronds to indicate water stress.   Use a soil wetting agent as a preventative measure in any watering plan and try not to let the palms dry out.  In production "high hole" pots are often used to provide a water reservoir at the bottom of the pot.  High hole pots have the drainage holes set about an inch and a half above the bottom of the pot.  Many roebelenii are sold like this and it is a good idea to check the holes on a new roebelenii so that you know if that reservoir exists or not.

Nutrition: 

     Most of the directions for other palms apply to roebelenii as well. A fertilizer with a 2:1:2 ration with about half as much magnesium as potassium is a good starting point.  Too much fertilizer may result in burnt tips. It should be noted that palms move some nutrients from older leaves to newer leaves before dropping the oldest leaves.  Premature pruning prevents the recycling of nutrients and requires them to be added manually.  If too many older leaves are bad looking, address this problem with a better fertilizer program and try to keep pruning of older fronds to a minimum.

Insects and Mites:

     Mites, mealybugs and scale are pests of roebelenii.  Look for scale and mites on the underside of the fronds.  Scale will leave very distinct colorless feeding lines in the leaf that are visible from the top of the leaf.  Mealybugs are usually first seen down in the growing point where the immature fronds are being formed.  Carefully separate the immature fronds to look inside this new growth to check for mealybugs.   For treatment see the Insects and Mites section in the general information section below.

General Information

Insects and Mites:

By far the only reasonable treatment for Two Spotted Spider Mites(TSSP) on palms are predator mites.  If the mites are red in color, then the normal predators may or may not help with the problem.  There are a couple of types of red mites that can be a problem on palms, including an invasive species called Red Palm Mite (RPM) that was identified in 2007.  More common is a type of red spider mite that is noticeably different than RPM.  Sprays may be the best available treatment.  The ideal solution would be to contact an agriculture extension office or other professional in your area for identification then check with suppliers of predator insects to determine if a predator is available.  For mealybugs and scale, in an interiorscape, a combination of systemic insecticides, hand cleaning, and spraying should be used.  The larger the palm, the more preventative your treatments should be.  Drench with a systemic insecticide every 4-6 months to prevent problems.  On easier to maintain palms, use hand cleaning to remove a large percentage of the population, then treat with either sprays or systemic drenches.  Always consider the nutritional status of the plant when treating for insect problems.  A healthy plant will resist infestations by insects.