Zantedeschia, commonly known as Calla Lilies, Arum Lilies, or Pig Lilies, are easily grown almost everywhere.
There are two different types- the evergreen species Zantedeschia aethiopica, which includes Hercules, White Giant, Spotted Leaf, Aethiopica, and others; and the colored hybrids, often called Mini Callas. The two types are grown quite differently!
Aethiopica varieties 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 skinny 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.
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.
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! Plant the bulbs 3-4 inches deep, with the growing point upwards. 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. 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.
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 once every two weeks.
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.
After your plant blooms, the flower will start to close and turn darker and sometimes green on the outside. 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!
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!
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.
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.
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. 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.
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!
How to grow Calla Lilies (Zantedeschia)
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