fortnight lily plant

Fortnight Lily (Dietes iridioides): How to Grow and Care

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The fortnight lily goes by many names, including African iris, butterfly iris, Wood iris, and scientifically Dietes iridioides. The name fortnight lily is based on the blooming cycle of the flowers, where new blooms come up approximately every two weeks.

A fortnight is a time period of two weeks, originating from an old English term that meant fourteen nights.

With new blooms every two weeks, your fortnight lily will be bursting with color all season, which for the fortnight lily is unusually long. In the correct growing zones, fortnight lilies will bloom from spring to late fall, sometimes even into the winter months in warmer climates.

What Are Fortnight Lilies?

fortnight lily flower

Fortnight lilies are evergreen perennials in USDA hardiness zones eight through eleven. In cooler climates, these flowers can be grown as annuals that bloom in the summer months.

The fortnight lily can also be grown in a container that can be brought inside or added to a greenhouse when temperatures start to drop.

The fortnight lily is also referred to as the African iris and the morea iris. It’s a species of plant in the Iridaceae family (and the genus Dietes) and is native to Southern Africa.

The flowers on a fortnight lily will either have bright-white petals with a dab of yellow at the base surrounding a light purple center, or an off-white color with maroon blotches towards the center. Whichever color variety you choose, the flowers that form will be beautiful.

Thankfully, there are few pests and diseases that will harm your fortnight lilies, they are fairly hardy. Fortnight lilies look best when grown in large clusters, creating a sea of flowers in your landscaping.

There is little not to love when it comes to these flowers although those of us in the cooler growing zones may wish they were cold-hardy.

dietes iridioides

How to Grow and Care for Fortnight Lilies

Growing fortnight lilies is a relatively easy project you don’t necessarily have to have a green thumb. Particularly once established, the fortnight lily can tolerate nearly any living situation. 

Poor soil and limited amounts of water won’t phase it, although ideal conditions will yield the highest number of flowers. If you do want to keep your fortnight lilies in the best possible condition, not much effort is needed well worth the reward of more flowers!


The ideal location for fortnight lilies is somewhere with full-sun exposure. Sunlight helps promote flower growth and strong blooms, so the more the better. These flowers originate from Africa, making them highly heat-resistant—too much sun isn’t something to worry about here. 

If you have a location where you want to plant fortnight lilies that are partially shaded, that should be fine as well. Although the flowers thrive in full sun, you will still get decent blooms if the plant is shaded for part of the day.


Although fortnight lilies have been known to grow in low-quality soil, their ideal soil type is well-drained with moderate levels of natural fertilizer.

If your soil does not drain well and your fortnight lilies are not thriving, tilling up your garden or landscaping patches before planting may help. 

Some choose to grow these flowers in their garden beds or in containers to ensure they are getting the ideal soil mixture. For the most part, better soil will directly correlate with more blooms on your fortnight lilies.


fortnight lily

These adaptable flowers will learn to grow in drought-like environments as well as water-saturated environments, although neither is ideal. When growing fortnight lilies, it is best to keep the soil moist as a general rule. 

For most climates, a solid watering once per week should be enough to keep the plant happy and healthy. If you are getting little to no rain, it may be a good idea to add a second weekly watering into the mix to ensure your plant has the energy needed to bloom its beautiful flowers.  


There are a few reasons and ways to prune your fortnight lily to keep it healthy and to get the highest number of blooms.

If you do not plan to keep seeds from your fortnight lily plant, cutting off the seed pods when they first form will keep the plant from seeding and will result in more flowers. 

Although most of the dead flowers will fall off on their own, pruning off the spent flowers will reserve energy for new blooms and will make your plant look nicer overall.

The same goes for the foliage, any dead or yellowing foliage can be cut off at the base to reserve energy for new growth.

Every few years, it is a good idea to cut your entire fortnight lily plant down to ground level. This should be done in the fall when the plant is in a dormant state.

Removing the above-ground portion of the plant will give it a chance to reset itself—in a way—and start over fresh. Although it may not look pretty after cutting it, beautiful new leaves and flowers are sure to follow.


Fertilizer is not always necessary for the fortnight lily plants, but certain fertilizers can help your plant grow new flowers, particularly if your soil nutrient levels are low.

When planting your fortnight lilies for the first time, it is a good idea to work some organic materials into the soil for added nutrients.

Once the plant is established, adding some organic fertilizers to your plants once a year can help to keep them in their healthiest state. When your flowering plants are healthy, you are sure to get plenty of beautiful flowers.

African iris

Where to Plant Fortnight Lilies

Fortnight lilies are a versatile flower that can be planted nearly anywhere. These flowers will look great in any location either as a main attraction or as a supplement to the rest of your flower garden.

The delicate look of the fortnight lily can add small sections of color to your landscaping, but when planted in large clusters can create an explosion of color that looks great anywhere.

Garden Beds

Garden beds create an ideal growing environment for fortnight lilies. Garden beds can be set up in a way to create the proper drainage needed to achieve the highest number of blooms on fortnight lilies.

Planting in garden beds also allows you to add in the best possible potting soil that will provide the nutrients that the fortnight lilies thrive on.

If you are building garden beds specifically for your fortnight lilies, areas that receive full sun exposure are ideal. Garden beds that can be moved around are a neat way to change up your landscaping each year—or if you just change your mind. 


Fortnight lilies also make good container flowers, and they’re commonly grown in containers in cooler climates where these flowers cannot grow as perennials.

When planting in containers, it is a good idea to choose a size that can be transported if you are planning on bringing them inside during the winter.

Your fortnight lilies may also require some additional nutrients when planted in containers, as there won’t be as much soil to pull nutrients from. A yearly fertilizer should keep the plant healthy and the flowers blooming.

Around a Water Source

A popular location for planting fortnight lilies is around water sources such as ponds, lakes, and pools. The fortnight lilies have a tropical look to them that makes a water-side location a perfect area to admire them.

Due to the high water tolerance of the fortnight lily, you won’t have to worry about some light flooding damaging your flowers. The fortnight lily is also drought-resistant if your water source ends up drying out more than usual.

Fire-Prone Areas

If you live in an area that is prone to fire outbreaks, the fortnight lily may be a good option for your landscaping. The fortnight lily is considered a fire-resistant flower. 

Although not fire-proof, the fortnight lily can withstand the environment that comes along with fire such as high temperatures and smoke.

If the flowers or foliage of your fortnight lily are singed, the plant can be cut back and should regrow itself the following season.

Wood iris

Are Fortnight Lilies Poisonous?

Although not highly toxic, certain parts of the fortnight lily are poisonous to people and most animals. Ingesting parts of the fortnight lily plant can cause stomach pain, vomiting, and other unpleasant symptoms, but it is rarely life-threatening unless a copious amount is consumed.

It is a good idea to watch children and pets that are around your fortnight lilies to ensure they don’t eat the plants.

For some, handling fortnight lilies can cause skin irritation, especially if the plant is cut open. This minor irritation generally goes away after a short amount of time, and washing your hands well may speed up the process.

Pests and Diseases that Affect Fortnight Lilies

For the most part, fortnight lilies are fairly resistant to most pests and diseases and can generally fight away any that do come along. However, when caring for your fortnight lilies, there are a few pests and diseases to keep an eye out for just to make sure your plants are staying in tip-top shape.

Scale Insects

Scale insects are a pest that can harm your fortnight lilies if you have a large infestation that is not under control. Scale insects attach themselves to the foliage of the plant and suck out the nutrients. After some time, the leaves of the plant will start to yellow and may start to fall off.

To get rid of scale insects, wiping them off with cotton swabs dipped in rubbing alcohol should do the trick. If there is too large of an infestation, you can create a spray made of water, alcohol, and certain insecticidal soaps and lightly spray the plant daily until the insects are gone.

Foliar Nematodes

Foliar nematodes are a pest that causes damage to the leaves of fortnight lilies. These nematodes will create water-soaked lesions that cause the leaves to turn dark colors over time. 

If the problem is not resolved in time, the infection can spread and cause stunted growth in new leaves.

The most effective way to help your plant after a nematode causes damage is to remove any of the damaged parts of the plant so the infection will not spread.

Root-Knot Nematodes

Root-knot nematodes are similar to the foliar nematodes but attack the root system of the plant. These pests form galls on the root system that can alter the growth of the plant.

The galls that form stunt the growth of the plant and can cause long-term damage if not taken care of early on in the infection process.

Root-knot nematodes are more difficult to get rid of than foliar nematodes because the damage they create is on the root system.

After root-knot nematodes have caused damage, the best course of action is usually to remove the plant altogether so that other plants nearby do not become infected as well. 


Rust is a fungal disease that affects many plants, fortnight lilies included. Although rust may not cause much harm to your fortnight lilies, it is a good idea to get rid of this fungal disease before it gets out of hand, as it can spread to the remainder of the infected plant along with other nearby plants. The leaves of the infected plants will start to yellow and may, over time, wilt and fall off.

To eliminate rust from your flower garden or landscaping, the most effective method is to remove damaged foliage or whole plants if they are heavily affected. Foliage or plants that are removed should be destroyed to ensure the fungal disease does not come back.

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