How to grow moonflowers

• Written by Holly Hughes on February 22, 2022

Opening their large, white, trumpet-shaped flowers to balmy summer evenings, moonflowers are a magical and fragrant addition to any garden. In this quick and easy guide, we’ll take you through everything you need to know about how to grow this exquisite and sweet-smelling bloom, whose heart-shaped leaves and trailing vines add instant elegance to every garden.

In this article, we will look at:

• Are moonflowers annuals or perennials?
• How to grow moonflowers from seed
• How to plant moonflower seeds
• Moonflower light requirements
• Moonflower soil requirements
• Moonflower water needs 
• How to care for moonflowers

Let’s get started!

Are moonflowers annuals or perennials?

Originating in subtropical regions, moonflowers are typically winter-hardy perennial plants. The moonflower growing zones are 10-11 but they can also successfully thrive in cooler zones as annuals.

How to grow moonflowers from seed

Moonflowers are easy to grow from seed and can be started indoors six to eight weeks before outside soil is properly warmed.

Moonflower seeds have a notoriously hard seed coat that can disrupt germination as it inhibits water and moisture absorption. However, these seeds demand a lot of water in the first stages of germination which is why it is often best to start them indoors where you can ensure they are adequately hydrated. Soil that dries out – even if only for a brief amount of time – can be enough to kill a moonflower seedling before it even has a chance to show you it is there.

The best way to grow moonflowers from seed is to soak the seeds in water overnight. To further aid germination, you can carefully cut the seed’s hard exterior using something like a nail file which will help the seed absorb moisture.

Having soaked them, transplant the moonflower seeds into two-inch pots filled with good potting soil, planting them roughly half an inch below the surface. Leave your pots in a well-lit area that is at least 60-70 degrees Fahrenheit, taking care to keep the soil moist and conditions humid.

The majority of moonflower seeds should start to germinate in 3-4 days, though some can take several weeks.

How to plant moonflower seeds

After 6-8 weeks of germination indoors, when the last frost has passed, the ground has warmed, the weather settled, and Spring has well and truly arrived, it is time to plant your seeds outdoors.

This you can do in either large containers (which you can then bring indoors during the winter) or directly into the ground.

As moonflowers are keen climbers, make sure to sow them in an area that has a trellis or other structural support to encourage vine growth. The moonflower growth stages will see this plant bloom during summer or fall. So rapid is its growth that these vigorous vines can grow up to 20 feet in a single season, wrapping themselves around anything in their reach.

To fully savor their delicious fragrance, consider planting them around your house where they can climb walls or trellises, bringing their sweet fragrance into your bedrooms and living spaces on warm summer nights.

Let’s look now at the best moonflower growing conditions to consider when transplanting your germinated seeds.

Moonflower light requirements

A general rule for knowing how much light your moon flower needs is: the more sun it has, the more blooms will grow.

Heat and sun act like a catalyst for this plant. Growing slowly in cooler climates with often few or even no flowers, moonflowers growing under full sun will speed up their growth producing their biggest and best flowers. Thus, for optimum growing conditions for your plant, be sure to plant it in a place that will receive at least six hours of direct sunlight.

If this isn’t possible, don’t worry! These plants are very adaptable and so still can be grown in a more shaded spot. However, it is likely their growth will be more sluggish in the shade and produce less impressive results.

Moonflower soil requirements

Moon flowers can generally survive in any soil type, though they generally do best in a neutral to slightly acidic soil pH. What is important to note about your soil type is its ability to retain moisture. If soil is too soggy, it can cause root rot. If it is dried out for too long, it can cause your seedlings to perish.

However, given this is a plant used to subtropical environments, moisture and humidity are important for its survival. Adding mulched topsoil will help it retain the right level of moisture. Fertilizer can also be used to encourage flower growth but is not essential.

Moonflower water needs 

As you can probably tell from this plant’s soil requirements, it needs a moderate amount of moisture when growing. Though it requires regular watering when germinating and young plants need soil that is consistently moist (but not soggy), once the early sprouting stage is over, moonflowers only need to be watered when the soil is dry.

In fact, these plants can even withstand short periods of drought once established. However, until that time, make sure to keep soil consistently moist but never overwatered as this will surely lead to root rot.

How to care for moonflowers

Having provided these essential conditions for your germinating plant, what else can you do for optimal moon plant care?

Luckily, moonflower vines need only basic maintenance and rarely contract pest or disease problems. Once you have ensured your plant is adequately fed and watered, the only thing left to do is prune and deadhead it as needed.

If growing outdoors as a perennial, prune and shape the plant in the fall. Thinning the stems will increase airflow around the plant and expose it to more sunlight which, as we know, is vital to flower production.

Moonflowers are truly mesmerizing to watch come to life, particularly as their trumpet-shaped flowers elongate with every passing day. Now you know how simple they are to grow and care for, add them to your garden or houseplant collection next Spring, for a little bit of magic!