Skip to Content

Make Kalanchoe Bloom via Short-Day Lighting Techniques

Ever wonder why your Kalanchoe, that cute little flower that brightens up the sparse winter months, isn’t blooming as expected? You probably picked it up from the store, charmed by its beauty, but then found it stubbornly refusing to bloom the following year.

I’ve been there too! Let me share a little secret: Kalanchoe is a short-day plant. Without the right short-day treatment, it might delay blooming or not bloom at all.

The blooming process is tied to the plant’s exposure to varying lengths of daylight, affecting the production of specific hormones in plants. To see those lovely blooms within the year, a bit of effort is needed.

Understanding the Characteristics of Kalanchoe Flowers

Kalanchoe, belonging to the family Crassulaceae and genus Kalanchoe, loves sunlight and is a short-day succulent.

These plants primarily hail from Madagascar and East Africa, with some species in South Africa, Ethiopia, India, China, and Brazil.

They range from small, 4 inches (about 10 cm) ground-covering types to towering varieties nearly 10 feet (3 meters) tall. Depending on the species, you’ll find a variety of leaf colors, flower hues, and shapes.

Blossfeldiana Variety: This is the one you often see in stores. Its small flowers sit at the end of elongated stems, typically in colors like red, orange, pink, and yellow.

Kalanchoe ‘Wendy’: This variety boasts bell-shaped flowers, rich in deep reddish-purple with yellow edges, giving it a luxurious look.

It has some cold tolerance and can survive winter above 0°C (32°F). Originating from a Dutch university, this variety is compact and blooms abundantly.

Kalanchoe Pumila: This variety grows to about 20 cm (about 8 inches) and spreads out low to the ground. Its name ‘pumila’ means ‘small’, fitting for its petite stature.

The leaves are covered in fine hairs, giving them a white appearance, and they leave a powdery residue when touched.

Also known as ‘Silversheen’, it blooms in early spring with adorable four-petaled pink flowers.

It’s relatively cold hardy, capable of surviving winter as long as temperatures stay above 0°C (32°F) and it doesn’t freeze.

What is Short-Day Photoperiodism?

Short-day plants require a period of daylight shorter than a certain threshold to initiate flowering.

In natural environments, as the days shorten to less than 12 hours during fall and winter, these plants begin forming flower buds. Then, around February of the following year, they bloom.

Is It Good to Keep Them in Sunlight?

Too much direct sunlight can scorch the leaves. During summer, it’s best to place them in a spot with good air circulation that’s shaded from the harsh afternoon sun.

If you’re growing them on a balcony, be mindful of radiated heat as well.

How Much Cold Can They Tolerate?

They aren’t very frost-hardy, handling temperatures only down to about 41°F (5°C). In winter, a sunny spot indoors near a window is ideal.

Should I Water Them Daily?

These plants are sensitive to overwatering. Water them when the soil’s surface turns white and feels dry.

Both overwatering and low temperatures can cause them to wither. During the rainy season, water sparingly to prevent mold.

What Type of Soil is Best?

Plant them in well-draining soil. A mix of medium to small red balls (5 parts), peat moss (2 parts), and river sand (3 parts) is ideal.

Why Aren’t My Kalanchoe Blooming?

With proper care, Kalanchoe can bloom from fall to spring. If left to grow naturally, they typically bloom after winter. However, insufficient sunlight can prevent blooming.

If the environment drops below 50°F (10°C) after buds have formed, their development slows, and they might not bloom until spring warms up. Growth halts at about 41°F (5°C). 

Keeping them in a warm, sunny indoor spot during winter will encourage buds formed in late fall to bloom from winter onwards. Continuous exposure to artificial light at night can hinder blooming.

Grow them away from fluorescent lights and other light sources. To encourage blooming in fall, perform short-day treatment in summer.

How to Perform Short-Day Treatment for Blooming Kalanchoe

Ever wondered how to get your Kalanchoe to bloom using short-day treatment? I just wanted to share some of my experiences with growing Kalanchoe, especially about how it blooms.

You know, I learned that Kalanchoe won’t flower without short-day treatment. But here’s the question: does it need the same treatment after the first flowers bloom to get the next buds?

I was really worried because I often leave the lights on in my room until late at night. 

Under normal care without short-day treatment, around late September to early October, or speaking in terms of daylight hours, when there are about 12 hours or less of daylight for around 20 days, flower buds start forming.

This usually results in blooming around February of the next year. The short-day treatment for Kalanchoe takes advantage of this characteristic.

It involves intentionally creating a slightly longer period of short days, say around 10 hours of daylight for 30 days, to ensure more reliable bud formation and control the flowering time.

There are various methods for short-day treatment, but covering the plant with a cardboard box is the simplest, so let me tell you about that.

For instance, if you want your Kalanchoe to bloom for the New Year’s celebrations, start in the middle of summer, around August.

Cover your potted Kalanchoe with a cardboard box from about 6 PM to 8 AM the following morning. This creates an environment without any light. It’s essential to do this for about a month (30 days).

If you forget to cover it or do it at different times, it might not work as well, but a little deviation is usually okay.

When you do this in August, the daylight hours for the Kalanchoe become about 10 hours, making the plant think the days are getting shorter and start the bud formation process.

After 30 days of short-day treatment, you can return to normal care and wait excitedly for the flowers to bloom.

Once the buds are formed, you don’t need to worry about the daylight hours until the next year when it’s time for another round of short-day treatment.

Here’s an extra tip: using this characteristic, you can make Kalanchoe bloom whenever you like. By preparing several pots and staggering the short-day treatment for each, you can enjoy Kalanchoe flowers all year round.

And about the idea of continuous blooming throughout the year with a single plant, it’s more about adjusting the flowering periods rather than extending them.

While it’s not typical for a single plant to bloom all year round, using the short-day treatment, you can enjoy flowers throughout the year with different plants.

Now, here’s how I did it in easy to understand steps: 

July to August: Create Short-Day Conditions

  • From around 5 to 6 PM in the evening until 7 to 8 AM the next morning (July through August), I cover my kalanchoe with cardboard. This strategic manipulation of daylight hours creates short-day conditions.
  • Ensure there are no gaps in the cardboard to maintain complete darkness. You can also cover it with a cloth for added darkness.
  • Keep doing this daily for 30 to 40 days until buds appear.
  • By reducing daylight hours to about 10 hours, you’ll be able to see beautiful flowers by year’s end.
  • Once you remove the box, place the plant near a sunny window to give it plenty of sunlight.
  • Kalanchoes are short-day plants that develop buds as the length of daylight decreases. If they’re in a spot that’s lit at night, they’ll think the days are longer, which can hinder bud formation.
  • This short-day treatment tricks the plant into blooming earlier by intentionally shortening the days.

What to Do During Kalanchoe’s Blooming Period?

Once your Kalanchoe starts flowering, here’s what you should do. Place it near a window to ensure it gets plenty of sunlight. Water it generously when the surface of the soil turns white and dry.

Kalanchoe prefers dry conditions and doesn’t like being waterlogged, so avoid overwatering. Be careful not to get water on the flowers and leaves, as they can easily get damaged.

Regularly deadhead the flowers by cutting off spent blooms at the base. Once a month, give it a diluted liquid fertilizer, mixed to about half of the recommended strength.

Key Takeaways

  • Short-day treatment for kalanchoes is surprisingly simple. Just cover them with cardboard daily until buds form, which should take about a month. But remember, the process doesn’t end after a month; continue until you see buds.
  • Once buds appear, grow them near a sunny window.
  • With patience, you’ll be rewarded with beautiful blooms before the year is over.
  • Since kalanchoes don’t like too much moisture, water sparingly.

Sharing is caring!