Successfully establishing and multiplying white calla lilies is a rewarding endeavor that begins with a solid understanding of the correct planting techniques and propagation methods. This process is not merely about placing a rhizome in soil; it involves careful timing, proper soil preparation, and precise placement to ensure the plant has the best possible start. Whether you are planting a newly acquired rhizome or expanding your collection by dividing an existing plant, the principles of encouraging strong root development and vigorous growth remain the same. Mastering these foundational skills is the first step toward cultivating a thriving display of these exceptionally elegant plants, ensuring their perennial return and the potential for sharing them with others.
The journey begins with the selection of high-quality, healthy rhizomes, which are the underground stems from which the calla lily grows. A healthy rhizome should feel firm and plump to the touch, similar to a small potato, and be free from any soft spots, mold, or signs of shriveling, which could indicate disease or poor storage. The size of the rhizome often correlates with the vigor of the plant and its flowering potential in the first year, so choosing larger, more robust specimens can provide a significant advantage. It is also important to look for small “eyes” or budding points on the surface, as these are the locations from which new growth will emerge.
Once a healthy rhizome is acquired, timing the planting is the next critical factor. The ideal time to plant white calla rhizomes is in the spring, after all danger of frost has passed and the soil has begun to warm up. Planting too early in cold, wet soil can cause the rhizome to rot before it has a chance to sprout. For those looking to get a head start, the rhizomes can be started indoors in pots about four to six weeks before the last expected frost date and then transplanted outdoors once the weather is consistently mild. This initial timing sets the stage for the entire growing season.
Proper soil preparation is a non-negotiable step for successful planting. White callas thrive in soil that is rich in organic content but also offers excellent drainage. For garden planting, amend the native soil with generous amounts of compost or well-rotted manure to improve its fertility and structure. If the soil is heavy clay, incorporating coarse sand or fine gravel is essential to enhance drainage and prevent the rhizome from sitting in waterlogged conditions. For container planting, a high-quality potting mix designed for flowering plants, often with added perlite or vermiculite, provides the ideal growing medium.
The planting process in detail
The actual process of planting the white calla rhizome requires attention to depth and orientation to ensure optimal growth. A common mistake is planting the rhizome too deep, which can delay or even prevent sprouting, or too shallow, which can lead to instability as the plant grows. The general rule of thumb is to dig a hole that is approximately 8 to 10 centimeters deep. This depth provides enough coverage to protect the rhizome while still allowing the emerging shoots to reach the surface without expending excessive energy.
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Correctly orienting the rhizome within the planting hole is another crucial detail. Upon close inspection of the rhizome, you will notice one side is typically smoother, while the other side has small, pointy growth buds or “eyes.” These growth points are where the leaves and flower stalks will emerge. The rhizome should be placed in the hole with these growth points facing upwards. If it is difficult to determine the top from the bottom, you can lay the rhizome on its side; the shoots will naturally find their way up towards the light and the roots will grow downwards.
After placing the rhizome in its proper orientation, gently backfill the hole with the prepared soil, being careful not to compact it too tightly. The soil should be firm enough to hold the rhizome in place but loose enough to allow for easy root penetration and water drainage. Once planted, the area should be watered thoroughly to settle the soil around the rhizome and eliminate any air pockets. This initial watering also provides the necessary moisture to signal the rhizome to break its dormancy and begin the growth process.
Following the initial planting and watering, patience is key. It can take several weeks for the first shoots to emerge from the soil, depending on the soil temperature and the vigor of the rhizome. During this time, it is important to keep the soil lightly moist but not saturated. Overwatering before significant foliage has developed is a common error that can lead to rot. Once the first leaves unfurl, the plant will begin to photosynthesize actively, and its water requirements will increase, signaling the start of its vigorous growth phase.
Propagation through rhizome division
Propagation by division is the most common and reliable method for multiplying white calla lilies, allowing you to expand your collection or share with fellow gardeners. This process involves carefully separating a mature, overgrown rhizome clump into smaller, viable sections, each capable of growing into a new, independent plant. The best time to divide calla lily rhizomes is during their dormant period, typically in late autumn after the foliage has died back, or in early spring before new growth begins. Attempting to divide the plant during its active growth phase can cause significant stress and set back its development.
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To begin the division process, the entire rhizome clump must be gently lifted from the soil, whether it is in a garden bed or a pot. Use a garden fork or spade to carefully dig around the perimeter of the plant, taking care not to pierce the rhizomes. Once the soil is loosened, lift the entire clump and gently shake or brush off the excess soil to get a clear view of the rhizome structure. You will likely see a dense mass of interconnected rhizomes of various sizes.
With the rhizome clump exposed, you can identify the natural points for division. The goal is to separate the clump into smaller sections, ensuring that each new piece has at least one or two visible growth eyes or buds. In many cases, smaller rhizomes can be gently broken off from the main clump by hand. For larger, more established clumps, a clean, sharp knife or pruning tool will be necessary to make clean cuts. It is crucial to use a sterilized tool to prevent the introduction of disease into the fresh wounds.
After dividing the rhizomes, it is a highly recommended practice to allow the cut surfaces to cure for a day or two before replanting. This allows a protective callus to form over the wound, which significantly reduces the risk of rot and fungal infections once the rhizome is back in the soil. Place the divided pieces in a dry, well-ventilated area away from direct sunlight. Once cured, these new rhizomes can be planted according to the standard planting guidelines, and they will develop into new plants, genetically identical to the parent, in the following growing season.
Growing callas from seed
While division is the most common propagation method, growing white calla lilies from seed presents a unique and interesting challenge for the patient gardener. This method is more time-consuming and offers more genetic variability, meaning the resulting plants may not look exactly like the parent plant, which can be an exciting prospect. The process begins with harvesting seeds from a mature calla lily flower after it has faded and the seed pod has developed and ripened, which is indicated by the pod turning yellow and soft.
Once the seed pod is ripe, the seeds must be extracted and cleaned. Carefully open the pod and remove the seeds, then wash them thoroughly to remove the fleshy, gel-like coating that surrounds them. This coating contains germination inhibitors, and failing to remove it will significantly reduce the chances of successful sprouting. After cleaning, the seeds should be sown immediately, as they do not store well and have the best germination rates when fresh.
To sow the seeds, prepare a seed tray or small pots filled with a sterile, well-draining seed-starting mix. Lightly press the seeds into the surface of the mix and then cover them with a very thin layer of soil or vermiculite, no more than half a centimeter deep. The medium should be moistened gently but thoroughly, and then the container should be placed in a warm location with bright, indirect light. Covering the tray with a plastic dome or clear plastic wrap will help maintain the high humidity levels that are conducive to germination.
Germination of calla lily seeds can be slow and erratic, often taking anywhere from a few weeks to several months. During this time, it is crucial to keep the growing medium consistently moist but not waterlogged. Once the seedlings emerge and have developed a few true leaves, the plastic cover can be removed to improve air circulation. The seedlings are delicate and should be grown on in their containers for several months until they have developed a small rhizome and a strong root system before they are carefully transplanted into individual pots or their final garden location. It is important to note that plants grown from seed will typically not flower for at least two to three years.
Container planting considerations
Growing white calla lilies in containers is an excellent option, offering versatility in placement and making it easier to manage their environmental needs, especially in climates with harsh winters. The selection of the right container is the first step and is critical for success. The pot must have adequate drainage holes at the bottom to prevent water from pooling around the rhizome, which is the most common cause of failure in potted callas. The size of the container is also important; it should be large enough to accommodate the rhizome and allow for root growth, but not so large that the soil volume stays wet for too long. A pot approximately 15-20 centimeters in diameter is often a good starting point for a single rhizome.
The choice of potting medium for containers is just as crucial as the pot itself. A high-quality, well-aerated potting mix is essential. Avoid using heavy garden soil, which compacts easily in pots, restricts root growth, and retains too much moisture. An ideal mix would be one based on peat or coir, amended with perlite, vermiculite, or coarse sand to enhance its drainage properties. This type of medium provides the perfect balance of moisture retention to keep the roots hydrated and the aeration needed to prevent suffocation and rot.
When planting the rhizome in a container, the depth should be slightly shallower than when planting in the garden. A depth of about 5 to 7 centimeters is generally sufficient. Place the rhizome with the growth eyes facing up on a layer of the potting mix, then cover it with more mix, gently firming it down. Water the pot well after planting to settle the soil, and then place it in a location that receives bright, indirect sunlight. As with garden planting, do not water heavily again until you see the first signs of green shoots emerging from the surface.
One of the major advantages of container growing is the ability to control the plant’s environment precisely. Potted callas can be moved to find the optimal light conditions, brought indoors to protect them from frost, and easily managed during their dormancy period. After the foliage dies back, watering can be stopped completely, and the pot can be moved to a cool, dark, dry location like a garage or basement for the winter. This simple management of the dormant phase ensures the rhizome gets the rest it needs to produce a spectacular show of flowers the following season.
