Tips for Growing Lilies in Greenhouse

The global cut flowers market was valued at USD 37.45 billion in 2023 and is expected to grow at a compound annual growth rate (CAGR) of 4.8% from 2024 to 2030. Among the wide varieties of cut flowers, the Lilium (lily) segment is set to grow the fastest, with a projected CAGR of 6.4% during this period.

Lilies, known for their elegant beauty and captivating fragrance, have been cherished for centuries. They are a popular choice in the cut flower market due to their versatility and aesthetic appeal. Interestingly, lilies can be cultivated in greenhouses with flowering achievable within just six weeks of planting under the right conditions.

However, while the market potential is promising, consistently achieving high-quality lily production in greenhouses is more challenging than it may initially appear.

In this blog, we will share practical tips for successfully growing lilies in a greenhouse, helping you maximize both yield and profits.

Understanding lily varieties

Traditionally, lilies have been categorized into three main groups: Asiatic, Oriental, and Longiflorum hybrids. However, advancements in interspecific hybridization have resulted in the creation of new lily groups. These hybrids combine the best traits of various types, such as improved resistance to diseases.

When selecting lilies to grow, it’s important to consider the environmental conditions of your cultivation area and the preferences of your customers. For example, some customers may prefer lilies with large, showy flowers, while others might favor varieties with strong, fragrant scents.

Below are features of some of the most common lily varieties available in the market:

Preparation before planting

Growing lilies as cut flowers in a greenhouse requires the right type of facility, as maintaining a stable climate is crucial for successful commercial cultivation. Proper climate control simplifies the process of forcing lilies to grow and flower. Key factors such as temperature, air circulation, ventilation, and lighting must be accurately regulated to ensure optimal growth.

The ideal greenhouse height is 4 to 4.5 meters, providing ample space for installing screening, irrigation, and lighting systems. A greenhouse with a retractable screening system is preferable to a fixed one, as it allows better utilization of natural light. The best screening systems are those that minimally reduce light intensity when not in use, ensuring maximum light availability.

In addition to having the right equipment and structure, weed control is an often overlooked yet essential aspect of greenhouse lily cultivation. Prior to planting, creating a weed-free environment is critical for healthy growth. While chemical weed control should only be used as a last resort due to potential damage to the lilies, manual methods such as weeding, hoeing, or soil disinfection are more sustainable and effective alternatives.

Creating the ideal greenhouse environments

For optimal outcomes, you must provide the ideal greenhouse environments for lilies.

Temperature

Cooler temperatures are essential for proper rooting in lilies. For the first two to three weeks, it is recommended to maintain a low temperature of 10°C to 12°C to support the development of stem roots.

After rooting, the optimal temperature settings vary depending on the lily group. For Asiatic and LA hybrids, the ideal temperatures are 10°C to 13°C at night and 18°C during the day. Other lily groups require slightly higher temperatures, with 14°C to 16°C at night and 18°C to 20°C during the day.

For early spring and late fall production, a heating system is necessary to maintain the minimum required temperatures. Conversely, during summer, soil cooling becomes crucial, as lilies cannot tolerate extreme heat. It is important to ensure that greenhouse temperatures do not exceed 25°C during summer cultivation to protect the plants from heat stress.

Lighting requirements

Lilies thrive best in full sunlight but can also tolerate partial sun. However, inadequate lighting can lead to several issues, including flower bud drop, desiccation of buds, taller and weaker stems, and lighter-colored foliage. For optimal growth, greenhouse lilies require a minimum light intensity of about 4 mol/m²/day.

To promote healthy photosynthesis, begin supplemental lighting as soon as the foliage emerges. This additional lighting is particularly important from late September to early April, ensuring sufficient light during shorter days. During this period, supplemental lighting also helps extend the day length to 16 hours, which is crucial for optimal lily growth in the greenhouse.

Consult Us to Find the Perfect Grow Lights for Your Lilies!

Humidity and air circulation

Greenhouse lilies grow best in a relative humidity range of 70% to 80%. However, during the winter months, humidity levels can rise excessively due to reduced plant transpiration. To maintain the ideal humidity levels and support proper transpiration, heating, and ventilation can be used to lower humidity effectively.

Another critical factor during winter and early spring is CO₂ injection. This technique can boost the weight of certain lily cultivars, enhancing their overall quality. For greenhouse lilies, maintaining a CO₂ concentration of 800 ppm is sufficient to achieve these benefits.

Soil and nutrient

Lilies thrive in slightly acidic soil, which supports healthy root development and proper nutrient absorption. If the soil pH is too high, it can hinder the uptake of essential elements such as phosphorus, manganese, and iron.

For Asiatic, LA, and Longiflorum hybrids, a soil pH of 6.0 to 7.0 is ideal. In contrast, Oriental, OA, LO, and OT hybrids perform best in soil with a pH of 5.0 to 6.5.

In addition to pH, lilies require well-drained soil but not waterlogging, which can damage the roots and impede growth.

Watering

Both overwatering and underwatering can delay the emergence and growth of lilies. Lilies require substantial amounts of water, especially during the initial phase of stem root development. Once the stem roots are fully established, water requirements can be gradually reduced.

In greenhouse cultivation, an irrigation system ensures uniform water distribution without compromising the soil structure. Regular monitoring of the irrigation system is essential to maintain a well-balanced moisture environment, which is crucial for healthy lily growth.

Environmental control for optimal results

By managing specific environmental factors in greenhouses, you can achieve desirable outcomes, such as promoting flowering, accelerating the growth of lilies to bring them to market sooner, and controlling their height to enhance market value and profitability. One common method is using supplemental lighting to regulate day length and induce flowering. Another effective approach is managing the temperature differences between day and night.

Day length can affect the flowering of lilies

The number of hours of light lily plants receive within a 24-hour period (known as the photoperiod) significantly impacts their flowering. Lilies classified as "long-day plants," such as Oriental and Easter lilies, require longer daylight hours to stimulate flower induction. To promote flowering during shorter days of the year, LED grow lights are used to extend the photoperiod. Typically, this long-day treatment increases the day length in greenhouses to 16 hours.

This method is especially beneficial for timing lily blooms to coincide with holidays, allowing growers to bring them to market earlier. By doing so, it helps growers maximize their profits.

Controlling Plant Height

For lilies grown for sale as cut flowers, plant height is a critical factor influencing their market value. Since temperature impacts plant height, you can regulate the greenhouse environment to achieve your desired final height.

The key factor is the DIF—the difference between day and night temperatures. This difference significantly affects plant growth:

• Positive DIF (+DIF): Warmer days than nights promote stem elongation.
• Negative DIF (-DIF): Warmer nights than days inhibit stem elongation.

Lilies grown under the same DIF will generally reach similar heights, regardless of the specific daytime or nighttime temperatures.

However, managing DIF can be challenging when outdoor temperatures fluctuate widely during the growing season. In such cases, another effective method is to lower the air temperature significantly at the end of the night and during the very early morning. This timing takes advantage of the plant’s natural growth response, helping control height more effectively.