When Do Monstera Split or Fenestrate?

When do Monstera split or fenestrate? Is it after they mature when they are 2-3 years old? Why is mine not splitting? How does Monstera split? These are familiar questions.

We will tell you whether all Monstera species split or fenestrate, why it happens, and how. Also, give you reasons why your Monstera is not splitting and eight ways to encourage it to develop those huge pinnatifid and fenestrated leaves.

Lastly, split means pinnatifid, and fenestration means holes or windows on leaves.

Do all Monstera leaves split?

No. Not all Monstera have split leaves. Some will only have fenestrations or holes, and their margin will remain entire, and others will have both. There are also Monstera species that may have only split while others will hardly have any splits or holes.

For instance, Monstera siltepecana has fenestration or holes only. They occur in a series of 2 to 4 holes on either side of the lamina.

On the other hand, M. deliciosa has splits (pinnae) and holes (fenestration) in a series of 1 to 5.

From observation, most species that produce holes early are likely split (pinnatifid). If it begins growing the second series of perforation, you will have a plant with both fenestrations and splits.

Species with split and fenestrated leaves include:

• M. deliciosa
• Monstera dubia
• M. epipremnoides
• M. pinnatipartita

Those that have leaves with entire margin but develop holes or fenestration include the following:

• Monstera adansonii
• M. acuminata
• M. adansonii var. laniata
• Monstera siltepecana
• M. acacoyaguensis
• M. lechleriana
• Monstera obliqua

Some Monstera species will have leaves that have splits only, i.e., they don’t have fenestration or holes. These species include

• M. subpinnata
• M. dissecta
• Monstera spruceana

That is not all. Some Monstera species will have no splits or fenestration, but their leaves will enlarge. Here the only species is M. Standleyana. But in some cases, it may have very few holes.

Lastly, one not officially accepted species, M. Peru’s leaves, remain the same in juvenile and mature stages. But they may only look a little larger.

Why do Monstera leaves split or fenestrate?

Many theories explain the fenestration and splitting of Monstera and other plant species. These explanations include the following:

1. To allow water to trickle to their roots: Since they have huge leaves, if they were not split or fenestrated, they would act like an umbrella which will prevent water from reaching their roots. Remember, these plants never develop a very pronounced rooting system.
2. Resist strong winds or rainforest hurricanes: Splitting and fenestration may help Monstera leaves better resist rainforest hurricanes and winds by allowing them to pass through.
3. Capture more sunfleck: As secondary hemiepiphytes grow beneath tall tree canopies, they only get filtered light or beam of light that makes it way beyond the canopy (sunfleck). When it goes through the holes (windows), it will cover a larger area than those without these windows. This is according to Christopher Muir of Indiana University. Remember, light spreads out as it travels.
4. Prevent leaves from overheating: The holes break any still air in-between layers of leaves by promoting the convention. So, these plants’ leaves will not overheat when exposed to too much light.
5. It helps them grow over a large area while using little energy: With holes, these plants can spread over a large area to get light without using much energy and resources to grow an entire leaf.

As tropical plants, it is easy to dismiss the first two theories. Why? Water isn’t a problem in these areas, and other plants with similarly large leaves don’t have holes.

How do Monstera leaves split or fenestrate?

Monstera leaves split or fenestrate as they are formed, i.e., the leaves will have holes or splits as they develop before they unfurl.

The holes occur from programmed cell death, i.e., early in development, the leaf blades of Monstera form distinctive perforations through the death of discrete patches of cells. These minute pinprick-size perforations extend about 10,000-fold in the area as the leaf expands to form conspicuous holes in the mature lead,” states a study.  

Cell death causes tiny empty spots during a leaf’s early development, which become more significant as the leaf grows bigger.

Then exact split pattern or fenestration is genetically controlled. Also, it begins when the plant has a certain age or growth conditions.

For those with splits and holes like Monstera deliciosa, you will start by noticing perforations and then splits before they can have both.  

When to Monstera fenestrate?

Monsteras have three growth stages, the seedling or baby, the juvenile, and the mature or adult stage. The seedling is when it still depends on the seed for some resources. Saying it begin at the juvenile stage doesn’t answer the question correctly.

To give you the when answer, Monstera splits when they are about ½-3 years, depending on the species and growing conditions. There is no way to tell when exactly fenestration or splitting will occur.

Remember, some species like M. obliqua will mature within 1½ years, and others like M. lechleriana after 8 years. But they will start splitting or having windows before they are fully mature.

That is not all. Some species like M. deliciosa may start having holes with the 5^th or 6^th leaf. How soon this occurs depends on growth conditions.

Last but not least, variegated Monsteras like Thai constellation, var.  borsigiana albo, aurea, etc., will take longer to get splits and holes. Why? They have a slower growth rate since they have lesser chlorophyll.

Why is Monstera leaf not splitting?

If your Monstera leaf is not splitting, the possible reason is that your plant is young or doesn’t get enough light, water, humidity, temperature, or nutrients. The other possible factor is a climbing place.

Light, nutrients, humidity, water, or temperature are all factors that influence growth rate. When unmet, your plant will grow slowly or less vigorously. It means it will take a long to mature or start producing fenestrated and pinnatifid leaves.

On the part of climbing, except for Monstera deliciosa, the rest of the species require a climbing place to grow to maturity. This tells you that a climbing place may make your plants grow adult leaves often split and fenestrated.

How to get monstera leaves to split – 8 ways

Split and fenestrated leaves are a unique feature that makes Monstera species a houseplant choice. It goes without a say that everyone wants their plant to grow these mature leaves.

Let us now tell you ways to encourage your Monstera to split or fenestrate.  

1. Provide bright, indirect light

Monstera needs bright, indirect light, about 10,000 to 20,000 lux (1,000 to 2,000 footcandles) for about 12 hours to grow optimally. You can an illuminance meter like Dr. meter LX1330B Digital Illuminance Light Meter to confirm if your light is sufficient.

If you are using grow lights, it should be in the 400–700 nm wavelength range that helps in photosynthesis. Read more on Monstera light need. A good brand to buy is Relassy 15000Lux Sunlike Full Spectrum Grow Lamp. It has a long lifespan (50,000 hours), a gooseneck stand very efficient.

Light helps plants make food necessary for growth using carbon dioxide and water.

Too little light will stunt growth, make leaves smaller, paler, and your plant leggy. Also, even those with split leaves may revert to entire juvenile leaves.

On the other hand, don’t be tempted to provide direct sunlight. It will cause sunburn on your Monstera, which will negatively affect your plant growth.

2. Water your plant well

Water is a crucial photosynthesis component and helps keep plants cool by transpiration. Also, it maintains cell turgor (turgidity), transports minerals from the soil, and is a medium for many biochemical reactions in plants.

If your plant doesn’t get enough water, it will grow slowly, have yellow leaves, droop or wilt, or suffer from leaf scorch (crispy brown tips and edges). Also, your Monstera may curl leaves inward, wither or even die.

Water your Monstera when the top 2-3 inches of the soil feels dry or up to the first knuckle of your finger.

Also, you can water it with your soil moisture sensor indicates dry zone. We have an XLUX Soil Moisture Meter, and water our Monstera plants when the reading is three or less. 

Don’t follow a schedule, and don’t overwater. Overwatering will cause root rot, yellowing of lower leaves, slow growth, and so on. See how often to water monstera, overwatered, and underwatered signs.

3. Feed your Monstera

Fertilizers and soil are a source of nutrients that plants need to grow. These nutrients form plant structures, help in photosynthesis, activate enzymes, etc.

Of the 17 essential nutrients plants need, they can only get hydrogen from water and carbon dioxide from the air. The rest you must provide. Otherwise, your plant will grow slowly, suffer from chlorosis, have smaller leaves that won’t split or have holes, and so on.

We recommend you ensure your potting mix is rich in organic matter. You can some compost or worm castings like Worm Castings Organic Fertilizer Wiggle Worm Soil Builder. It will provide some necessary nutrients like nitrogen, phosphorus, sulfur, potassium, calcium etc. 

Then, feed your Monstera using an all-purpose, balanced liquid fertilizer for houseplants once a month during growing months (spring or summer). If you are growing your Monstera in water, go for hydroponic fertilizers.

We use Miracle-Gro Indoor Plant Food (Liquid) NPK 1-1-1. Four pumps per quart of water and use the solution to feed our Monstera plants. It works instantly.

However, you can also go for any other good brand, including Espoma (organic), Bonide 10-10-10, etc.

4. Keep humidity at optimum

Do Monstera love humidity? Yes. These tropical rainforest plants flourish moderate to high humidity, 50% or more. Low humidity will cause brown edges and tips on leaves (leaf scorch), yellowing, slow growth, wilting, and leaves curling. Leaves may not split.

Humidity plays a critical role in keeping stomata open. This way, plants can absorb carbon dioxide to make food or exchange gases. Open stomata will also help keep the plant cool via transpiration.

On the other hand, transpiration creates the force that pulls water and minerals from the soil.

If your home has low humidity, mist your plant, have a pebble tray, or buy a humidifier like AquaOasis™ Cool Mist Humidifier (Amazon's best-seller). You can also group plants if you have many or take them to the bathroom, kitchen, or rooms with higher humidity.

5. Repot your plant regularly

Not repotting may not be a reason for your Monstera leaves not splitting, but it becomes a factor if your plant is rootbound.

They have outgrown the pot when rootbound and cannot get enough nutrients or water. So, your plant will become leggy and have smaller leaves. Sometimes, it may stop splitting. Other issues will be slow growth, yellowing of leaves, leaf scorch, etc.

When actively growing, your Monstera needs repotting yearly or when rootbound. Once they mature, you can do it after 2 to 3 years or if it outgrows the pot.

6. Stake your Monstera

Staking isn’t a prerequisite for Monstera leaves splitting or fenestration. But it may have an influence. Why? Because as a hemiepiphyte, these plants only mature when climbing or going to the epiphyte stage. Also, these plants grow larger leaves when given a stake.

Why not try giving your Monstera a staking plant with a moss pole to see if it will fenestrate or split? There are many good moss poles at Amazon. Pick extendable ones if your plant is tall.

7. Prune older leaves

Many gardening enthusiasts attest that your plant will produce larger leaves by pruning lower, older leaves and may start having holes or splitting sooner. We don’t have any explanation as to why this happens.

8. Be patient

If you have a young plant that hasn’t reached a splitting or fenestration stage, providing all the above will only make it happen a little faster but not immediately.

Be patient. It will start producing those pinnatifid or perforated leaves when the time is right. You cannot force it to start immediately.

A good analogy will be feeding your baby so well, expecting them to turn into adults after a year. It takes time.