Zanzibar Gem / ZZ Plants

Zamioculcas zamiifolia

Contents

1. Top Tips
2. Light, Water, Humidity & Fertilisation
3. Common Issues
4. Origins, Temperature, Propagation, Repotting & Toxicity.

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Top Tips & Info

• Care Difficulty - Easy
• ZZ Plants must endure dry periods between waters - if you're stuck with when to water it, think of the ukhouseplants' phrase of 'Drenches Between Droughts'.
• Be careful when watering - allowing excess moisture to sit in the cubbyholes of the lower stem will result in diseases such like stem (petiole) or tuber rot. 
• Provide a bright, indirect location away from the summer sun. ZZ Plants are a great choice for statement specimens in a shady room, as long as they're kept on the drier side to life.
• Fertilise every three months all year round, using either a 'Cactus' or 'Houseplant' labelled feed.
• Repot every two years during the spring, using a 'Cacti & Succulent' potting mix. Roots that bend the pot's side or poke through the drainage holes are a good sign that it'll need repotting!

Location & Light - 🔸🔸🔸

Although differing light levels are all acceptable, a sunny window with morning or evening sun will work wonders. Along with Pothos, Peace Lilies and Sansevieria, these are an excellent choice for dark locations, but always regulate the amount of water it receives as too much will kill the plant outright. Be sure to allow the soil to fully dry out for at least two weeks to totally eliminate the chance of soil-borne diseases. Never place a ZZ Plant is more that three hours of intense sunlight a day as its ability to bounce back from scorched leaves may take several months.

Water - 🔸

The ukhouseplants saying, 'drenches between droughts' strongly applies to ZZ Plants. Not only will continuous soil moisture start to destroy the root system, it'll also cause the plant's tubers to begin to rot, killing it from the inside out. Allow all of the soil to fully dry out in between waters in summer for around a week or so, while reducing this further during winter. Under-watering symptoms include a weakened grey stem, yellowing leaves, little to no growth and dry, crispy patches forming on the leaf edges; these issues are usually caused by too much light/heat or forgetfulness. Remember, the brighter the location, the more watering you'll need to do. Over-watering symptoms include a weakened grey stem, leaves that have a rotten base, no new growth, yellowing leaves and plant death. The differences between under and over-watering are very similar; a rotten root ball will stop the plant soaking up vital moisture and nutrients, leaving you with wilted grey leaves. For more severe cases of root rot, click here!

Humidity -

Low humidity is fine with ZZ Plants, as long as its foliage is hosed down from time to time for the removal of dust particles and potential pests. Those situated in dark locations or bathrooms mustn't be over-misted, as it could cause powdery mildew or botrytis.

Fertilisation - 🔸

Fertilise every three months using either 'Cactus' or 'Houseplant' labelled feed. Never directly pour 'Ready to Pour' product directly into the soil without a quick wash down with water as this will lead to burning roots.

The beautiful leaf structure of the Zamioculcas zamiifolia.

Common Issues with ZZ Plants

The biggest issue with ZZ Plants is root or tuber rot, commonly caused by too much soil moisture and too little light. Typical symptoms include yellowing leaves, a collapsed base or wilting. Periods of dryness is mandatory for all succulents, especially with those situated in darker locations.

A deformed pot is the product of its strong tuberous roots travelling through the soil and therefore shouldn't cause concern. We would recommend repotting it into the next sized pot with a 'Cactus' labelled potting mix. Scroll down to 'Repotting' to learn more about what to do!

Directly pinpointing yellow leaves is quite hard, due to the many different issues that could be at fault. Problems include watering-related abuse, too much or too little light or over-fertilisation. Do not directly apply 'ready to pour' feed into the soil without a pre-water as this will lead to the burning of roots. Too much direct sunlight is another common culprit, with the foliage typically curling over time.

Yellowed leaf-sections with browned areas can be a product of many issues, wrapped up as one. Firstly, the location may be too dark, with its compost staying too saturated in-between waters; if mould is growing across the soil, this is usually a bad sign. Further, you're potentially using too cold water or tap water that hasn't been allowed to sit for 24hrs. This period of rest will not only bunk-up its temperature, but the harsh chemicals used to preserve water hygiene (fluoride & chloride) will begin to alleviate after a few hours. If possible, use fresh bottled water from a shop or supermarket to prevent further chemical burns. The final culprit might be lack of fertilisation, with regular feeds being paramount for long-lasting, healthy leaves. If the specimen hasn't been nourished in over two months, it'll begin to show signs of nutrient deficiencies seen in this article.
If this common problem has occurred with your specimen, remove the affected leaves (not sections on the leaf) and improve the growing conditions considerably. Fertilise regularly with lukewarm water and be sure to allow the top third to dry out in between hydrations. Its new growth should be problem-free, but if you'd like to speak to ukhouseplants for more advice, don't be afraid to book a call with Joe Bagley.

If your ZZ Plant develops basal collapse, it may spell the end of its life. The tubers, which are located below the soil line and act like a modified stem, is the lifeline for a successful specimen, so any issues of rot will kill it outright. If yours has problems of this, be sure to take the plant out of the pot and inspect its roots. Prune away any rotten areas and check its base for a softened profile. Remove any individual plants that have a rotten bottom and repot the healthy specimens in a fresh batch of 'Cactus & Succulent' compost. Provide a brighter location and reduce the number of waters slightly to avoid further rot. Discard the plant if there is no sign of health below the soil line, which is usually mushy with a rotten smell.

Failed propagation via leaf cuttings is a common issue among amateur horticulturalists due to its complexity and lack of matured specimens. The first reason why the cuttings have failed is down to the maturity of the plant itself. Leaves must only be removed off the petiole once the plant has produced petioles that are over 80cm in length, as too little leaves less than 9cm in length won't store enough energy to produce tuberous growth.

Finding a brown crispy leaf that is wrapped around the base of the stem (pictured below - central top) is nothing to worry about, as it's just the reminiscence of the cataphyll that protected the bud whilst under development. Simply remove the leaf from the base to prevent the chance of disease.

Zamioculcas have special adaptations to withstand the East African weather; both the modified stems (tubers (pictured)) and its tuberous petioles store water for reserves of up to two months.

Origins

Zamioculcas is a genus of one species, the Z. zamiifolia, originating from Kenya in eastern Africa. Although the genus was first described in 1829 by Loddiges as Caladium zamiifolium but was quickly moved into the current genus by Schott; its final botanical name, Z. zamiifolia was penned by Adolf Engler in the late 19th century. The name is a nod to both the Cycas genus of Zamia, and that of Colocasias which itself has derivations from the Arabic word, culcos.

The Distribution of Zamioculcas zamiifolia.

Temperature

15° - 32℃  (59° - 90℉)
H1a  (Hardiness Zone 13)  - Must be grown indoors or under glass all year round. Never allow temperatures to dip below 15℃ or permanent damage may occur in the likes of flower loss, stunted growth and yellowed leaves.

Spread

The overall size can be up to 0.8m in height and 1.5 m in width, with matured petioles reaching over 1m in length. The ultimate height will take between 6 - 10 years to achieve when repotted biannually, with two or three new growths per annum.

Pruning & Maintenance

Remove yellowed or dying leaves and plant debris to encourage better growth and all-round growing conditions. When removing dying flowers or leaves, use clean scissors or shears to reduce the chance of bacterial and fungal diseases, and remember to make clean incisions as too much damage can shock the plant.

The cataphyll may need to be removed once fully browned over; this is located at the stem's base and can be seen on the image above.

Propagation

Via Seed, Tuber Division or Leaf Cuttings. 

Division (Moderate) - For this method, it's best to divide in spring or summer and once the tuberous offsets are at least half of the size of the mother plant's. If you have several established specimens within the pot, you'll have the option to individually separate them to double your stock. Always pre-water the soil at least 24hrs before propagation to avoid damaging the dry root hairs, which will lead to transplant shock and inevitable death. Remove it from the pot and place your hand in between the two tubers - soil may have to be removed to get a better grip. While placing your hand firmly around the junction, gently push the offset downwards, supporting the mother plant - you should hear a snap. Cautiously separate the two roots systems, keeping great empathise in keeping the specimens intact and damage-free. Place the new plantlet in a well-draining potting mix, much similar to the original soil, and maintain the same care routines. 'Cactus & Succulent' compost is best, or you can make your own using multipurpose compost with a generous amount of grit, sand and perlite. Make sure not to use a pot that is too big as a ratio of roots-soil that leans towards the latter will cause root rot and eventually plant death.

If there are visible signs of rot towards the bottom half of the stem - take leaf cuttings as the disease may travel to the top. The red lines indicate where to cut for leaf propagation.

Leaf Cuttings (Difficult) - Leaves that are halfway along the petiole have the most potential due to its size and maturity. Gently place your fingers between the petiole and the leaf's base, pulling it downwards until you hear a snap. Ensure the wound is wholly intact with no damage as a tear will result in unsuccessful propagation. Set the bottom half into moist 'Cactus & Succulent' compost and place the pot in a transparent bag to provide high humidity. Open it up for an hour every few days to allow fresh air to circulate the leaf. Offer a bright, indirect setting with temperatures around 18°C (64°F) with the majority of the soil drying out in between waters. The calloused base will develop into a tuber, thus signalling the propagation success. After a few months, inspect its root system and transplant into a bigger pot if necessary. 

The successful development of its tuber, which will act as a 'bulb' where new growths will emerge. 

Flowers

As they form part of the Araceæ family, their flowers aren't showy. Much like a Peace Lily's flower body, their flowers consist of a white or green spathe (the spoon-like shell) with the spadix being the section that can be pollinated. Blooms can last up to five days and is usually visible during late spring or early summer around 20cm from the soil line. Unfortunately, producing blooms is a rare occurrence due to the unfavored growing conditions found in a typical domestic setting.

The flowers of a ZZ Plant. Copyright: Garden.org, Hamwild.

Repotting

Repot every two years in spring using a 'Cactus & Succulent' labelled potting mix and the next sized pot with adequate drainage. ZZ Plants are far better being potbound for several years due to the heightened risk of root rot and repotting-issues (like transplant shock) - so only repot if you feel it's wholly necessary. Deformed plastic pots caused by the underground growths are standard and won't necessarily require a bigger pot.

Hydrate the plant 24hrs before the tinkering with the roots to prevent the risk of transplant shock. For those situated in a darker location, introduce an extra amount of perlite and grit into the deeper portion of the pot to downplay over-watering risks. Click here for a detailed step-by-step guide on transplantation, or via this link to learn about repotting with root rot.

Pests & Diseases

Keep an eye out for spider mites, aphids, scale, thrips, whitefly, blackfly, vine weevils & mealybugs. Common diseases associated wth ZZ Plants are root or tuber rot, red leaf-spot, botrytis & southern blight - click here to learn about these issues.

Toxicity

Members of the Araceæ family typically contain poisonous calcium oxalate crystals, with Zamioculcas being no exception. Other members of this family include Philodendron, Alocasia and Spathiphyllum (Peace Lilies). If eaten, vomiting, nausea with a loss of appetite could occur and consumption of large quantities must be dealt with quickly.

Retail Locations

Dobbies,  IKEA,  Blue Diamond,  Online Stores.

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