Your Guide to Planting Tree Lilies
Planting tree lilies involves preparing the soil, choosing the right depth, and spacing them appropriately to support their impressive stature. These tall hybrids, often known as trumpet lilies, demand attention and require specific conditions for their bulbs to establish successfully and produce their characteristic tall stems and large, fragrant flowers.
- Prepare well-draining soil enriched with compost.
- Plant bulbs at the correct depth for support and winter protection.
- Ensure adequate spacing to allow for mature plant size.
- Select a sunny location that offers some protection from strong winds.
Understanding the needs of tree lily bulbs before you place them in the ground is crucial for their vigour and longevity. Unlike smaller bulbs, their size and growth habit mean they benefit from thoughtful placement and soil preparation. This approach not only aids their initial establishment but also contributes to their resilience throughout the growing season.
Preparing the Planting Site for Tree Lilies
Successful tree lily planting begins with selecting an optimal location. These lilies thrive in full sun, ideally receiving at least six hours of direct sunlight daily. However, a spot that offers some afternoon shade during the hottest parts of summer can prevent scorching, particularly for lighter-coloured blooms. Critically, the site must have excellent drainage. Lily bulbs are prone to rot in waterlogged conditions, so avoid areas where water tends to pool after rain.
Before planting, prepare the soil thoroughly. Loosen the earth to a depth of at least 25-30 cm. This is especially important for tree lilies, as their roots will need to penetrate deeply to anchor their tall stems. Incorporate a generous amount of organic matter, such as well-rotted compost or manure. This improves soil structure, enhances drainage in clay soils, and retains moisture in sandy soils, providing a nutrient-rich environment for the bulbs.
If you have particularly heavy clay soil, consider adding grit or perlite to further improve drainage. For areas prone to severe winter frosts, planting in raised beds can offer an additional layer of protection and ensure water drains away effectively. Testing your soil's pH is also beneficial; lilies generally prefer slightly acidic to neutral conditions, with a pH between 6.0 and 7.0. Adjustments can be made with lime for acidic soil or sulphur for alkaline conditions, following soil test recommendations.
Choosing the Right Soil Amendments
The quality of your soil amendments directly impacts the health of your tree lilies. Well-rotted compost is invaluable, supplying a slow release of nutrients and improving both structure and water retention. If using manure, ensure it is fully composted to prevent burning the delicate roots of the lily bulb. A balanced, slow-release fertiliser can also be worked into the soil at planting time, providing essential nutrients for initial growth and flowering.
When planting bulbs, it is often beneficial to add a small amount of grit or coarse sand directly into the planting hole. This creates a well-draining micro-environment immediately around the bulb, offering extra protection against moisture accumulation, which is a common cause of bulb rot. This practice is particularly recommended if your garden soil is prone to becoming heavy or compacted.
Planting Lilies in Pots or Containers
Tree lilies can also be successfully grown in containers, provided the pots are large enough to accommodate their substantial root systems and height. Choose a pot at least 30-40 cm in diameter and depth, with ample drainage holes. Use a good quality, free-draining potting compost, perhaps mixed with a little grit for added aeration. Place a layer of gravel or broken pot shards at the bottom of the pot to ensure unrestricted drainage before adding the compost and bulb.
When planting in containers, always err on the side of a larger pot; it provides more stability for the tall stem and more room for root development, reducing the need for frequent repotting.
The Process of Planting Tree Lily Bulbs
The technique for planting tree lily bulbs is straightforward but requires attention to detail. The general rule for planting depth is to cover the bulb with soil approximately three times its own height. For most tree lily bulbs, this means planting them about 15-20 cm deep. Deeper planting offers several advantages: it provides stability for the tall, heavy stems, protects the bulb from extreme temperature fluctuations, and encourages the development of basal roots, which are vital for anchoring the plant.
When placing the bulb in the prepared hole, ensure it sits on a level base of soil. If the bulb has roots already forming, position them downwards. Avoid planting bulbs too shallow, as they can be more susceptible to frost damage and may not develop strong anchorage, potentially leading to stems that flop over. Conversely, planting too deeply can hinder emergence or lead to bulb rot if the drainage is not optimal.
Spacing is another key consideration. Tree lilies can grow very tall and their stems can be quite thick, often producing multiple blooms. Allow a minimum of 20-30 cm between bulbs. This spacing provides adequate room for the plants to develop their full spread, prevents overcrowding which can lead to disease, and ensures each plant receives sufficient light and air circulation. If planting in groups, aim for an aesthetically pleasing arrangement that still respects the individual space requirements of each lily.
Planting Timing and Seasonal Considerations
The ideal time for tree lily planting is typically in the autumn, from September through to November. This allows the bulbs to establish their root systems before the ground freezes. Planting in autumn also benefits from the natural moisture in the soil, aiding establishment. If autumn planting is missed, bulbs can be planted in early spring as soon as the ground is workable. However, spring-planted lilies may take longer to establish and might have a slightly reduced flowering performance in their first year compared to those planted in the previous autumn.
If you purchase bulbs in spring and cannot plant them immediately, store them in a cool, dry, well-ventilated place. Ensure they are not stored in plastic bags, as this can encourage mould. You can also temporarily pot them up in peat or potting compost to keep them in good condition until you are ready to plant them in their final position.
Ensuring Stability for Tall Stems
Given their impressive height, tree lilies are prone to wind damage and may require support. Planting them in a location that offers some natural shelter, such as near a wall, fence, or amongst other robust shrubs, can be highly beneficial. This natural windbreak reduces the strain on the stems.
For added security, consider installing sturdy stakes at the time of planting. Place these stakes near the intended centre of the plant, ensuring they are deep enough to be stable. As the stem grows, you can gently tie it to the stake using soft plant ties. Avoid tying too tightly, as this can restrict growth and damage the stem. Supporting multiple points along the stem as it elongrates will provide the best stability. Alternatively, consider using lily cages or rings that can be placed over the emerging shoots in spring and provide support as the plant grows taller.
The success of tree lilies hinges on providing them with firm anchorage and adequate space, allowing their vertical growth to be supported rather than challenged.
Caring for Tree Lilies Post-Planting
Once your tree lilies are planted, consistent care is essential for their development into magnificent specimens. Watering is important, especially during dry spells, but always avoid waterlogging. Ensure the soil drains well, and water deeply when the top few centimetres of soil feel dry. Mulching around the base of the plant with organic matter, such as bark chippings or compost, helps to retain moisture, suppress weeds, and keep the bulb area cool during summer.
Feeding is another aspect of post-planting care. While compost incorporated at planting provides initial nutrients, a top-up feed in spring, as new growth emerges, can be beneficial. Use a fertiliser that is relatively low in nitrogen but higher in phosphorus and potassium, which encourages flowering and strong roots. Avoid high-nitrogen fertilisers, as these can promote leafy growth at the expense of blooms, and can also make stems weaker and more prone to lodging.
Dealing with Pests and Diseases
Tree lilies, like other lily varieties, can be susceptible to certain pests and diseases. The most common pest is the lily beetle (Scarlet lily beetle), a bright red beetle that can strip leaves and flowers rapidly. Inspect your plants regularly, especially in spring, and hand-pick any beetles or their grubs. If infestations are severe, consider appropriate organic or chemical controls. Remember to check the undersides of leaves for eggs.
Fungal diseases, such as botrytis (grey mould), can also affect lilies, particularly in damp conditions. Good air circulation, proper spacing, and avoiding overhead watering, especially in the evening, can help prevent this. Promptly remove any affected leaves or stems to stop the spread. Ensuring robust plant health through proper planting and feeding is the best defence against most problems.
Encouraging Future Blooms
To encourage tree lilies to perform year after year, allow the foliage to die back naturally after flowering. Do not cut off the leaves and stems until they have turned yellow and withered. The foliage is crucial for photosynthesis, which replenishes the energy stores in the bulb for the following season's growth and flowering. Deadheading spent flowers by removing just the flower head can prevent the plant from putting energy into seed production and direct it back into the bulb.
For bulbs that have been in the ground for several years, you might notice a decline in flowering. This can happen if the bulbs become overcrowded. While tree lilies are not as prone to rapid multiplication as some other lily types, division might eventually be necessary. This is best done in autumn, after the foliage has died back, by carefully lifting the clump, separating the bulbs, and replanting them at the correct depth and spacing. This process rejuvenates the planting and ensures strong blooms for years to come.
After the flowering season, resist the urge to cut back the dying foliage; leave it in place for as long as possible as it feeds the bulb for next year's display.