GUIDE TO GROWING ZANTEDESCHIA (CALLA LILIES)

About Calla Lilies

Calla Lilies are native to South Africa.  There are seven species which grow in colors of white, yellow, and pink.

Hybridizers have created the summer blooming colored callas, which are sometimes  Mini Callas, although they grow from 8 to 30 inches tall and the flower diameter can be from 1/2 to 3-1/2 inches.   Callas come in almost every color- except blue!

Callas are grown in two different ways, and it's important to know what kind of calla you have so you know how to care for it.

Part 1- Growing the Evergreen species

    Aethiopica varieties (Aethiopica, Aethiopica Childsiana, Aethiopica Green Goddess) are bog plants, meaning they like a soggy soil, or an almost constantly wet area to grow in.  This plant is grown as a rhizome, a sort of a fat long bulb looking like a sausage or a hot dog.  Small bulblets grow along the side.  The rhizome should be grown vertically, with the growing points pointing upward.  Check the bulblets on the side- their pointed ends should point toward the sky.  Plant 3-4 inches deep in full sun to partial shade.  Keep the roots cool by top-dressing with mulch.  The white flowers appear most often in winter or spring, although they may appear any time.  Flowers can get up to 4 feet tall (rare) and up to 10 inches wide (rare).  Usually the flowers are 2-3 feet tall and 4-6 inches wide.

Aethiopica	Green Goddess	Aethiopica Rhizome Growing point by fingers 2 bulblets on side	Childsiana Rhizome Growing point by index finger

Part 2- Growing the Colored hybrids

The colored hybrids are called Mini Callas because their flowers are shorter than Aethiopica.  I think this is something of a misnomer, however, because some blooms can be quite tall (up to 26 inches) and quite large (up to 5 inches).  In any case, these hybrids are summer growers- although the breeders claim they can be grown year around.  Who wouldn't love growing these??

         

Colored callas love a sandy, well drained soil and full sun to partial shade.  They can be grown equally well in pots or in the ground.  Plant the bulbs after it is warm, since the WORST THING for bulbs is cold + wet, they will ROT!   
If you look at the bulb, one side should be wrinkly or smooth, and the other side should have some circles, with perhaps a tip poking out the middle of the circles.  The circles are where the growing points come out.  Some people say to look for a bulb with the most "eyes" to give you the most flowers.  In my experience that isn't necessarily true-I once was disappointed to get a 1 inch diameter bulb- until it put up 9 flowers!  Some varieties have naturally large bulbs and some are small.
Plant the bulbs 3-4 inches deep, with the growing point upwards.  Even if you plant Callas upside down or on their sides, they should sprout and grow just fine, so don't worry too much.  Callas like the sun, but they want their roots to be cool.  This is important.  Mulch the top of the soil if possible.

Top of bulb, with many "eyes" or growing points	Bottom of bulb, looks flat, often wrinkled.

Once you plant the bulbs, give them a little water and then WAIT until you see a leaf start to poke out of the soil, and then you can give them a little more water.  If you water them too much before they start growing, guess what?  That's right, ROT. 
If you plant the bulbs in fresh potting soil, you shouldn't need to fertilize, but if you feel the need, you can start fertilizing once all the leaves are open, and fertilize with a 200 ppm solution once every two weeks.  Avoid ammonium based fertilizer, they can lead to reduction in quality.  Long term release fertilizers can have the same effect.  Calcium and micronutrients will give you good healthy plants.

If you aren't sure about the soil in your yard, or you grow colored Callas every year but get no flowers, you might want to have your soil tested.  Look for your nearest Extension service or ask a local garden center for help.

Soil should be pH 6.0 to 6.5.  Too high a growing temperature can also lead to a lack of flowers, and heat stress can occur at 75 degrees.  Plants grow best at 65 degrees day  and 55 degrees at night.  Remember, these are optimal growing conditions.  Warmer conditions require a bit of shade to keep the soil cooler.  Remember, mulch helps keep the roots cool.

Part 3- The Bloom

The Calla Lily flower (correctly: inflorescence) has two parts- the um, little member sticking up in the middle, or spadix, and the colored (or white) wraparound part, or spathe.

The flower lasts a very long time, either on the plant or in a vase.  Some varieties are better suited to be cutflowers, but they all can be used to some extent.  It is very important to change the water every day.  Using a preservative in the water is best:  here is a home recipe from the wholesaler Florabundance:
1 teaspoon sugar
1 teaspoon household bleach
2 teaspoons lemon or lime juice
1 quart lukewarm water

Back to the garden:  after your plant blooms, the flower will start to close and turn darker and sometimes turn green on the outside.  If you go out to your garden and see a tightly furled green bloom, you've probably missed the actual blooming.  At this point you can cut off the flower or leave it on to form seeds.  Enjoy the beautiful foliage for the rest of the summer, though!  The leaves are quite lovely, and some of the spotted ones look almost like stained glass.

Flame, 3 days old	Flame, older (gets darker)	Flame, ending (darker, and sometimes gets spots)	Flame, ended (flower starts to close, outside turns very dark, leaves still nice and green)	Captain Kloon closing- turned green and flower closed up.	Leaves are just beautiful- can almost see through it.

Cutting the dead flower off will allow the bulb to start building up for the next year.  Make sure you leave the leaves, they provide the nutrients to let the bulb grow and reproduce.  Forming seed takes a lot of energy from the plant, so if you want the biggest bulbs next year, cut the dying flowers off.
A bulb has a set number of flowers it will put up, it isn't like other plants you "dead-head" to have continuous blooms.  Different varieties have different amount of blooms- some have only one or two, some will have six or more.      

Part 4- Seeds and growing from seed.

If you want seeds, leave the flower on the plant as long as possible.  You can peek inside of the spent bloom and you should see the start of a berry shaped fruit structure.  The longer you leave the flower on the plant, the bigger the fruit structure will grow.  I always leave mine on until fall, or until the flower stem (petiole) has completely wasted away- at that point you know no further nutrients will make it to the seeds.  The berry structure should start out green, and most of them will turn slightly yellow, some do stay green. 

You can pull one of the berries off the structure, and roll it and pinch it between your fingers and at least one seed should pop out.  Plant the seed in moistened potting mix and just cover it with a very small amount of the  potting mix.  Keep moist, and you will have baby callas sprouting in no time!  If the berries are already shriveled, you can just plant them without taking the seeds out, I've had good success both ways.

I start my baby callas in the winter (although you can start seed whenever you have it) , and then transfer them into the ground in the spring when I plant my other bulbs.  They should be slightly bigger than a pea at that point.  By the end of the summer you should have a small bulb.  It will take about 2 years or longer, depending on your growing conditions to get a bulb to flowering size.  NOTE:  The offspring may not look
like the parent flower!

Sprouting Seeds in a dish.	Transfer seeds to pots (or start them there)	Time to plant in the garden! See the baby bulbs?

Part 5- Calla lily diseases

Diseases:  Bugs don't really affect callas.  Occasionally you will see some aphid type creatures on the growing points before you plant the bulbs.  These can easily be brushed off. 
The worst disease Callas get is soft rot and Erwinia.  Erwinia is a common organism in the soil, but it will rush in and attack if the calla starts to get rot.  Callas rot because 1) they have been overwatered 2) they are overstressed due to their roots getting too hot.

Soft rot is terrible to see- you might have a group of lovely plants and flowers, then suddenly they turn mushy at the soil line and topple over.  If you dig the bulbs, they have a terrible odor and are soft and squishy too.

Breeders recommend discarding diseased bulbs so you don't spread the disease-- but in some cases the bulb may be saved.  Dig the bulb and rinse it off.  A hard spray from a garden hose will do.  The rotted areas will come off.  You may also cut away the rotted areas.  Then dust it with a fungicide such as Captan.  Dry the bulb until all the exposed areas (where the rot came off) have a callus and feel firm.  If you still feel soft areas, cut them away and repeat the drying.  As long as you still have a growing tip, you may be able to save the bulb.  Once the bulb is completely dry and firm, you can replant and hope for the best.  Again, don't water until the leaves start to show.  If it is close to fall, you may choose to simply store the bulb until the next growing season.

I've read that once rot attacks a garden area, it may wipe out the entire crop.  This has happened to me and another grower I know of.  It seems logical to stop watering once rot starts, but don't do it!  If it is hot, the unaffected bulbs could become stressed from overheating/lack of water and fall victim to the disease too.

The heartbreak of soft rot.

Part 6- Lifting bulbs or leaving in the ground?

In USDA zones 8 and 9, you can leave Callas (both hybrid and Aethiopica) in the ground year around.  In cooler zones, they should be dug in the fall.  For the colored callas, their leaves will start to turn yellow and die.  Dig the bulbs and let them dry for a few days.  Remove any foliage left and pull off the dry roots. 

Drying bulbs on our deck.	Another view of the bulbs.

The bulbs can then be stored in a cool spot.  They don't have to be put in a bag or stored in soil, they do appreciate good air flow to keep them dry. (Guess what happens if they stay wet).
If you are in a cool zone, you can dig Aethiopica and put it in a pot and bring it into the house.  Keep it in a well light area (near a bright window) and you should be able to keep it growing all winter- it may even surprise you with flowers in February. 

Of course, there are always exceptions to all these rules- I've heard of bulbs in zone 6 surviving the winter and growing the next year- but these are exceptions.  If the ground and bulb freeze, the bulb will die.
And, you can always leave the bulbs in the ground and treat them as annuals- simply buy new bulbs the next year.

Part 6- Calla Lily Questions.

Why won't my plants bloom?
There can be many be many reasons for it! 
Don't plant your Calla Lilies in heavy shade.  They need the sun to flower well.  Mulch around the leaves to keep the bulbs cool.
Have your Callas been planted in one place for a long time?  It might be necessary to separate the bulbs- as the bulbs get overly large, flowering drops off.  Wait until the foliage turns yellow in the fall, then dig and dry the bulbs.  Separate the bulbs by breaking them apart or cutting them apart (wear gloves, the sap may be irritating).  Make sure you have at least one "eye" in each section.  Let them dry well, and plant them (or wait until spring to plant) at least 6 inches apart.
Are you fertilizing?  Read your fertilizer container- there are 3 numbers on it, something like 10-10-10 or 15-5-1.  The first number is N, for Nitrogen.  This promotes good foliage growth.  The second number is P, for Phosphorus, which is essential for healthy growth of roots.  The third number is K, for potassium (also called potash).  It helps plants to resist diseases, protects them from the cold and protects during dry weather by preventing excessive water loss. It is also responsible for the new formation of flower buds.
Fertilize monthly with a good all-purpose fertilizer.
Watch your planting depth.  Bulbs that are planted too shallowly tend to get stressed, due to them getting too hot.  Bulbs that are planted too deeply often do not flower well.

Calla Overall Calla Lilies are pretty easy to grow.  We don't all have perfect growing conditions for them, but they will grow almost no matter what!  With just a little care, you can have some of the loveliest flowers- try it and see!

Susan Bryant
Lakeside Callas