Calla Lily - Zantedeschia

Zantedeschia aethiopica

Contents

1. Top Tips
2. Location, Water, Humidity & Fertilisation
3. Dormancy Period & Annual Flowers
4. Common Issues
5. Origins, Temperature, Propagation, Repotting & Toxicity.

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Top Tips & Info

• Care Difficulty - Moderate
• Situate your Calla Lily in a bright location with a minimal amount of direct sunlight. Those kept in deep shade are considerably more likely to develop shortened flowering times and even basal collapse.
• Allow the top third to dry out in between waters during the flowering process. Reduce this slightly in the autumn and winter to reinforce its dormancy, which in turn could entice a new show of blooms in the following summer.
• Fertilise once every two to four weeks using a 'Houseplant' labelled feed, depending on the season; fertilise soil will help prolong the flowers' lifespan.
• Keep an eye out for basal collapse, which is caused by over-watering and possibly too little light. Scroll down to 'Common Issues' for more information on this.
• Keep an eye out for Mealybugs and Spider Mites that'll inhabit the cubbyholes of its foliage.
• If your specimen is beginning to lose its leaves over the late summer onwards, don't be alarmed. Calla Lilies will go through a state of dormancy whereby most of the foliage will die back until the following spring. Scroll down to 'Dormancy Care & Annual Flowers' to learn more about this crucial period of its life!

Location & Light - 🔸🔸🔸

An hour or two of direct sunlight is best for quality growth. Never situate your Calla Lilly in a dark setting as the chance of bacterial diseases, like basal collapse, are far too likely for such an expensive specimen. The frequency of irrigations solely rely on the amount of sunlight received each day; those situated in slightly darker locations must be far less than with those in strong light. We'd recommend situating yours in a north, north-east or north-west facing window, or in a semi-shaded conservatory or porch. 

Water - 🔸🔸

Although outdoor Calla Lilies require relatively moist soil throughout the spring and summer, indoor specimens prefer to be slightly more on the drier side. This is because not only does the compost take longer to dry in domestic settings, but the rates of photosynthesis decreases, thus resulting in moister conditions. Allow the top half of the soil to dry out in between waters, reducing this further in the autumn and winter. In some cases, your Lilly may lose its foliage from late autumn onwards, which is normal behaviour for specimens at that time of year. Scroll down to 'Dormancy Care & Annual Flowers' for more information on what to do. Under-watering symptoms include a weakened stem accompanied by a loss of flowers, stunted growth and the greying or yellowing of leaves - these issues are commonly down to forgetfulness or too much heat or sunlight. Over-watering symptoms include yellowing of leaves, wilting, basal collapse, and plant death; these issues are commonly due to an area that's too dark, excess moisture in the soil, a too water-retentive compost or water-logging. Scroll down to 'Common Issues' for more information on how to address this problem. 

Humidity - 🔸

Average room humidity is more than enough to occupy an indoor Calla Lily, as too high humidity and poor air circulation will result in powdery mildew. Do not mist the flowers as this will cause botrytis petal blight that can spread quickly if not dealt with accordingly.

Fertilisation - 🔸🔸

Use a fertiliser high in potassium to prolong its flowers during the festive period, at fortnightly intervals - an excellent example would be a Tomato Feed. Regular fertilisers, for instance, BabyBio or Miracle-Gro, will still do the job but will favour foliar growth instead. For the rest of the year, a standard fertiliser can be used to supplement the plant, at monthly intervals.

Dormancy Care & Annual Flowers

Shortly after flowering, its foliage will begin to yellow and die off in the late autumn. Prune the foliage back just above the soil line using a clean pair of scissors or secateurs. Place the potted rhizomes in a dark location that provides low humidity and temperatures around 10°C  (50°F)  for a couple of months. Water sparingly so that the rhizomes are just 'ticking over' but keep in mind that too much soil moisture will cause root or pythium rot. Once foliage starts to re-emerge in spring, weakly fertilise the plant using a 'Houseplant' labelled feed and increase the number of waters per week. Relocate the specimen in a bright location with little to no direct sunlight so that it can acclimate to the new surrounding. Keep the soil moist, allowing the top third to dry in between waters and remember to keep an eye for the flower buds that'll develop at the top of the new rhizomatous growths.

Common Issues with Zantedeschia

Root rot is a common issue among specimens sat in too dark environments with prolonged soil moisture. Symptoms include rapidly yellowing leaves, mouldy soil, stunted growth and a rotten collapsed base. Take the plant out of the pot and inspect health below the compost line. If the roots sport a yellow tinge, you're good to go, but those that are brown and mushy must be addressed immediately. More information about managing root rot can be found on this link.

If your Lilly develops basal collapse, it may spell the end of its life. The rhizomes, 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 'Houseplant' 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. 

A dark location (shelves, etc.) will promote the rhizomes to develop small or no juvenile leaves, giving the impression of 'leggy' or naked growth. The length between the nodes will also dramatically become larger, harvesting less energy that can be converted into sortable sugars. Be sure to increase the amount of indirect light somewhat, and give the specimen a gentle supplement of 'Houseplant' labelled feed to help with its stored energy. 

Pests could arise at any time, with infestations starting from the original nursery or via contamination in your home. Spider Mites and Mealybugs to tend to be the usual inhabitants, with the first being minute and almost transparent, roaming the leaves in search of chlorophyll and a site to hide its eggs. The latter, however, will stand out much more, with white cottony webs developing across the foliage and stems. Thoroughly check the plant's cubbyholes before giving it the all-clear, or click on the appropriate links to learn more about eradicating these issues!

Curling leaves with crispy brown edges symbolise under-watering and possibly too much sunlight. As Calla Lilies tend to have extensive root systems, you may want to consider a transplant to reduce the number of waters with moister, fresh soil. Scroll down to 'Repotting' for more information!

Due to the species' sensitivity to chemicals, Leaf Shine shouldn't be used to improve the appearance of the foliage, and instead should be cleaned via a rinse of lukewarm water. Failure to do so may cause yellowed, mottled spots that cannot be undone.

A lack of flowers is caused by an insufficient dormancy period, where the temperatures are kept more or less the same over the year. Reduce the temperature by a couple of degrees over the autumn and winter months, along with fewer irrigations to ensure a well-spent dormancy. As spring arrives, the natural temperature will begin to increase, with this is being the perfect time to increase waters and fertilisation. Remember, the warmer the summer days are, the more likely a specimen is to reflower.

Origins

Zantedeschia consist of eight perennial species that originate from central to southern Africa. The genus was first discovered in the late 18th century by Kurt Sprengel and named in honour of Giovanni Zantedeschi, an Italian botanist and physician in the early 19th century.

The Distribution of Zantedeschia in Green  &  the most popular indoor species, Z. aethiopica, in Blue. 

Temperature

10° - 24°C  (50° - 75°F).
H1b (Hardiness Zone 12) - Can be grown outdoors during the summer in a sheltered location with temperatures above 12℃  (54℉),  but is fine to remain indoors, too. If you decide to bring this plant outdoors, don't allow it to endure any direct sunlight as it may result in sun-scorch and dehydration. Regularly keep an eye out for pests, especially when re-introducing it back indoors.

Spread

Up to 0.6m in height and 0.5m in width once they reach maturity. The ultimate height will take between 5 - 10 years to achieve.

Pruning & Maintenance

Remove yellow or dying leaves, and plant debris to encourage better-growing conditions. While pruning, always use clean utensils or shears to reduce the chance of bacterial and fungal diseases. Never cut through yellowed tissue as this may cause further damage in the likes of diseases or bacterial infections. Remember to make clean incisions as too-damaged wounds may shock the plant, causing weakened growth and a decline in health.

As mentioned in 'Dormancy Care & Annual Flowers', pruning your specimen back to an inch above the soil line is critical for its success in the following year. Remember always to use a clean pair of scissors and locate it in a bright, cool location with good air circulation.

Propagation

Via Seed & Basal Offset Division.

Offset Division (Pups) (Easy) - Separating the basal offsets into their own pot will not only expand your plant collection, but it'll also slow the process of becoming pot bound. The best time to divide is during the spring or summer, with the pup's height surpassing 10cm. Gently brush away some of the soil to gain better access to the pup's base, where its roots will be housed. While using a clean pair of secateurs or scissors, cut the cord with at least two root strands attached to its base. Set the pup in an appropriate-sized pot with adequate drainage and a houseplant-labelled compost. The ideal location would provide bright, indirect light and temperatures above 15℃  (59℉). Maintain evenly moist soil, allowing the top third to dry out in between hydrations. After a month or two, you'll be able to treat it like a matured specimen by using the care tips above.

Flowers

Most Zantedeschia will flower in summer, largely resembling that of a Peace Lily, with a coloured spathe protecting the spadix for pollination and enticing airborne insects. Zantedeschia will bloom between the months in spring and summer, but may even continue to bloom through the autumn. 

Repotting

During spring or summer, transplant every two or three years using a well-draining potting mix - this is an excellent time for rhizomatous division. For matured specimens, introduce slightly more grit to promote a sound root ball. For the first two years, you won't need to repot the plant while it's serving the dormancy period in winter. Instead, keep it potbound in its original pot which should help with stimulating better flowers in the spring onwards.

Book a 1-to-1 video call with Joe Bagley if you'd like a personal guide to repotting your houseplant. This will include recommending the right branded-compost and pot size, followed by a live video call whilst you transplant the specimen for step-by-step guidance and answer any further questions!

Pests & Diseases

Keep an eye out for mealybugs, spider mites, scale, fungus gnats, slugs, snails & root mealybugs that'll locate themselves in the cubbyholes and undersides of the leaves, with the exception of the latter in soil. Common diseases associated with Calla Lilies are root rot, leaf-spot disease, botrytis, rust, pythium rot, powdery mildew & southern blight - click here to learn more about these issues.

Toxicity

This plant is classified as poisonous, so if small sections are eaten, vomiting, nausea, and a loss of appetite may occur. Consumption of large quantities must be dealt with quickly; acquire medical assistance for further information.

Retail Locations

Most garden centres will stock Calla Lilies during late spring to summer months. Check for pests and diseases when introducing outdoor plants into the home, replacing the top few centimetres of the soil for precaution from larvae. 

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