How Much Light Do Microgreens Need?

Once microgreens have germinated and finished their blackout stage, light becomes one of the most important parts of growing a strong, healthy crop.

Too little light can produce pale, stretched seedlings that lean heavily towards the nearest window. Suitable light encourages compact growth, stronger stems, good leaf development and natural colour.

But more light isn't always better.

Putting a tray into intense Australian summer sun can introduce another problem: heat. A windowsill receiving direct sunlight can become considerably hotter than the surrounding room.

The goal is to provide bright, consistent light without overheating or stressing the crop.

This guide explains when microgreens need light, how many hours they need, whether window light is enough and when a grow light may be useful.

Microgreen Light Quick Guide

For the complete growing process from sowing through to harvest, see How to Grow Microgreens at Home in Australia.

When Should Microgreens Be Exposed to Light?

Microgreens don't generally need strong light during their initial germination and blackout stages.

During germination, the seed relies primarily on the energy stored inside it. Many microgreen varieties are initially covered, stacked or weighted to maintain moisture and encourage strong early development.

Once the crop has germinated and reached the appropriate stage, the tray is uncovered and moved into light.

This transition is important.

If microgreens remain in blackout too long, they can become excessively stretched, weak or tangled. If they are exposed too early, some crops may not receive the benefits of the germination and blackout period.

For more detail on deciding when to uncover a crop, see Microgreen Blackout Explained: Why, How & How Long?.

Why Are Microgreens Yellow When They Come Out of Blackout?

This is usually completely normal.

When seedlings develop in darkness, they haven't yet produced the same amount of chlorophyll they would under light.

Newly uncovered microgreens may therefore look:

• Yellow
• Pale green
• Creamy
• Slightly weak or stretched

Don't immediately assume something has gone wrong.

Once exposed to suitable light, many varieties begin greening relatively quickly. You may notice a significant colour change within the first day.

How Many Hours of Light Do Microgreens Need?

When using artificial lighting, approximately 12–16 hours of light per day is a useful general range for many microgreens.

A simple schedule might be:

Lights on: 6am
Lights off: 8pm

That provides 14 hours of light followed by 10 hours of darkness.

There is generally no need to run grow lights 24 hours a day.

When growing with natural light, you don't need to count the hours precisely. Instead, focus on providing a bright location with sufficient useful daylight.

Do Microgreens Need Darkness at Night?

Yes, a normal period of darkness is suitable.

Once microgreens leave blackout, they don't need to remain illuminated around the clock.

If you're using grow lights, a timer makes maintaining a consistent daily schedule easy.

A practical starting point is:

12–16 hours light → 8–12 hours darkness

The exact schedule doesn't need to be perfect to the minute. Consistency is more important.

Can You Grow Microgreens With Natural Light?

Yes.

A grow light isn't automatically necessary.

Microgreens can grow successfully using natural daylight if you have a sufficiently bright location.

The main challenge is that natural light varies considerably with:

• Season
• Window direction
• Weather
• Buildings and trees outside
• Distance from the window
• Time of day

A location that works very well in summer may provide much less usable light during winter.

Australian homes also vary greatly. A bright north-facing room can behave very differently from a shaded room receiving little daylight.

Watch how the crop responds rather than assuming every windowsill provides enough light.

Where Should Microgreens Go Near a Window?

Choose a bright location where the crop receives plenty of useful daylight without becoming excessively hot.

A tray doesn't necessarily need to sit directly against the glass.

Moving it slightly away from a hot window can provide plenty of light while reducing excessive heat.

This is especially important during Australian summer.

Direct sunlight through glass can rapidly heat:

• Leaves
• Growing medium
• Trays
• The air immediately surrounding the crop

Remember:

Light and heat are different growing factors.

If the tray is getting hot, stronger sunlight isn't necessarily helping.

For more information, see How Temperature Affects Sprouts & Microgreens.

Do Microgreens Need Direct Sunlight?

No.

Microgreens need adequate light, but they don't need to sit in intense direct sunlight all day.

Bright natural light can be sufficient.

Gentle direct morning sun may be suitable for many crops, but strong midday or afternoon Australian summer sun can be much more intense.

Watch both the seedlings and the growing medium.

If leaves are wilting, the tray is becoming hot or the growing medium is drying unusually quickly, the location may be too exposed.

Australian Summer Light

Australian summer sunlight can be intense.

A location described simply as a "sunny windowsill" in an overseas growing guide may behave very differently during a hot Australian January afternoon.

During summer:

• Avoid allowing trays to overheat behind glass.
• Be cautious with intense afternoon sun.
• Monitor growing-medium moisture.
• Move trays back from hot windows when necessary.
• Maintain good airflow.
• Remember that stronger light can increase water demand.

A bright indoor location without prolonged intense direct sunlight is often easier to manage.

Australian Winter Light

Winter presents the opposite challenge.

Days are shorter, the sun is lower and some indoor locations receive substantially less useful light.

You may notice microgreens:

• Leaning towards the window
• Developing longer stems
• Growing more slowly
• Appearing less compact

Move the tray to the brightest suitable location available.

If natural daylight remains insufficient, supplemental lighting can make growing much more consistent.

Why Are My Microgreens Leaning Towards the Window?

Plants naturally grow towards light.

If most of the tray is leaning strongly in one direction, the strongest light source is probably coming from that direction.

This is common when growing beside a window.

You can:

• Move the tray to a brighter location.
• Rotate the tray regularly.
• Use supplemental overhead lighting.
• Reduce obstacles blocking light from one side.

A slight lean isn't necessarily a problem.

A tray that becomes dramatically stretched and angled, however, is telling you that the light environment could be improved.

Should You Rotate Microgreen Trays?

When growing with light coming predominantly from one side, rotating the tray can help produce more even growth.

For example, turn the tray 180 degrees once a day if the seedlings consistently lean towards the window.

This isn't usually necessary when a grow light is positioned evenly above the entire tray.

Rotation doesn't replace adequate light.

If seedlings are extremely stretched, rotating them simply changes the direction in which they're stretching.

Signs Microgreens Aren't Getting Enough Light

Common signs include:

• Long, thin stems
• Excessive stretching
• Strong leaning towards a window
• Pale colour after the crop should have greened
• Weak growth
• Large differences between the bright and shaded sides of the tray

Some microgreens naturally grow taller than others, so stem length alone isn't proof of insufficient light.

Look at the crop as a whole.

If it is pale, weak and strongly reaching towards the light source, increasing usable light is a reasonable first adjustment.

What Should You Do if Microgreens Are Too Leggy?

First determine when the stretching occurred.

If the seedlings became very tall during blackout, the issue may be the blackout period rather than post-blackout lighting.

If stretching continues after uncovering, insufficient light is more likely.

Try:

1. Moving the tray to a brighter location.
2. Providing more consistent light.
3. Moving an existing grow light closer if appropriate.
4. Increasing the daily artificial-light period if it is unusually short.
5. Rotating window-grown trays.

Don't attempt to fix leggy growth by putting the crop straight into intense hot sunlight.

Increase useful light without introducing excessive heat.

Can Microgreens Get Too Much Light?

They can experience excessive light intensity, particularly when that light is accompanied by heat.

Possible signs include:

• Wilting during strong sun
• Rapid drying of growing medium
• Leaf stress
• Bleaching or discolouration
• Hot tray surfaces
• Crops recovering after the strongest sunlight has passed

If this occurs, move the tray away from intense direct sunlight and reassess the growing location.

Also check moisture.

Light, heat and water demand interact closely.

Natural Light vs Grow Lights

Both can work.

Natural Light

Advantages:

• Free
• No additional equipment
• Simple
• Can produce excellent crops in a bright location

Limitations:

• Changes with weather
• Changes with season
• Often comes predominantly from one direction
• Can introduce excessive heat through windows
• May be insufficient in dark rooms or winter

Grow Lights

Advantages:

• Consistent
• Controllable
• Can provide light directly above the crop
• Useful regardless of window orientation
• Makes year-round growing easier

Limitations:

• Requires equipment
• Uses electricity
• Position needs to be adjusted appropriately
• Some lights generate heat

Neither method is automatically better.

Use whichever provides a suitable and consistent environment for your crop.

Do You Need a Special Grow Light?

Not necessarily.

Microgreens don't require expensive specialist equipment simply because they're plants.

A suitable artificial light can work provided it delivers enough usable light over the growing area without producing excessive heat.

Purpose-built grow lights are convenient because they're designed for plant growth and often provide good coverage.

For small-scale home growing, the most important considerations are:

• Adequate brightness
• Even coverage
• Appropriate distance
• Suitable daily duration
• Manageable heat

If your existing lighting produces compact, green, healthy microgreens, there is no reason to replace it merely because another product is marketed specifically as a microgreen light.

What Colour Grow Light Is Best?

Full-spectrum or white grow lights are convenient for home microgreens.

They provide broad-spectrum light and make it easier to see the natural colour and condition of the crop.

Purple or red/blue horticultural lights can also grow plants, but they aren't necessary for producing good microgreens at home.

For most people, a good-quality white or full-spectrum light is more pleasant to use around the house and makes inspecting seedlings easier.

How Close Should Grow Lights Be to Microgreens?

There isn't one correct distance for every grow light.

Light output varies enormously between products.

A small LED strip and a high-output horticultural fixture should not be positioned using the same distance recommendation.

Follow the light manufacturer's guidance as your starting point.

Then watch the crop.

The Light May Be Too Far Away If:

• Seedlings stretch towards it.
• Stems become unusually long and thin.
• The crop remains pale.
• Growth is weak.

The Light May Be Too Close or Intense If:

• Leaves show stress or bleaching.
• The crop becomes unusually hot.
• Growing medium dries excessively quickly.
• Seedlings wilt despite adequate root-zone moisture.

Adjust according to the light and crop rather than following a universal centimetre measurement.

Should Grow Lights Be Directly Above Microgreens?

Generally, yes.

Positioning artificial lighting above the crop provides more even coverage and reduces directional leaning.

Try to illuminate the entire tray rather than creating one extremely bright area in the centre and dark edges.

If the edges of the tray consistently lean inward, light coverage may be too narrow.

Can Ordinary LED Lights Grow Microgreens?

Potentially, yes.

An ordinary LED can support plant growth if it provides sufficient usable light at the crop.

However, household lights vary greatly in brightness, spectrum and coverage.

A ceiling light several metres above a tray is unlikely to provide the same useful intensity as a suitable LED positioned relatively close to the crop.

The important question isn't simply whether the package says "grow light".

It is whether the crop receives enough appropriate light to grow compactly and green properly.

Does Light Affect Microgreen Colour?

Yes.

Light drives chlorophyll development, which is why many seedlings change dramatically after leaving blackout.

A pale yellow tray can become green relatively quickly after exposure to light.

Colourful varieties may also develop more characteristic pigmentation as they grow under suitable lighting.

However, final colour depends on the variety as well as the growing environment.

Don't expect every crop to become dark green. Red, purple and other varieties naturally have different pigmentation.

Does Light Affect Watering?

Indirectly, yes.

Brighter light — particularly when accompanied by warmer temperatures — can increase water use and evaporation.

A tray in a bright, warm location may dry more quickly than the same tray in a cooler, dimmer location.

Don't water according to the clock alone.

Check the growing medium and crop.

Once microgreens are established, bottom watering is often useful because it supplies water to the root zone without repeatedly wetting the foliage.

See How to Water Microgreens: Misting vs Bottom Watering for the complete watering method.

Should Microgreens Be Put in Light Immediately After Germination?

Not necessarily at the first visible sign of a root.

Many varieties benefit from a defined germination and blackout period before being moved into light.

The correct timing depends on the crop.

Use the individual seed instructions and assess how the tray is developing.

The goal is to move the crop into light once the germination and blackout stage has done its job — not simply according to a fixed number of hours.

Does Every Microgreen Need the Same Amount of Light?

No.

Microgreen varieties differ in:

• Growth rate
• Stem length
• Leaf structure
• Pigmentation
• Heat tolerance
• Light response

The 12–16 hour artificial-light range is therefore a useful general starting point rather than a rigid requirement for every crop and lighting system.

Watch how the crop responds and adjust where necessary.

Microgreen Light Troubleshooting Guide

Frequently Asked Questions

How many hours of light do microgreens need each day?

When using artificial lighting, approximately 12–16 hours per day is a useful general starting point for many microgreens.

A normal period of darkness at night is suitable.

Do microgreens need sunlight?

They need light, but it doesn't have to come directly from the sun.

Bright natural daylight or suitable artificial lighting can both be used.

Can microgreens grow on a windowsill?

Yes, provided the location receives sufficient light and doesn't become excessively hot.

Watch for strong leaning, stretching and heat buildup.

Should microgreens get direct sunlight?

Direct sunlight isn't required.

Gentle sun may be suitable, but intense Australian summer sunlight through a window can overheat trays and increase water loss.

Why are my microgreens yellow?

If they have just come out of blackout, yellow or pale seedlings are normal.

They should begin developing more colour once exposed to suitable light.

If they remain pale after receiving light, review the brightness and duration.

Why are my microgreens falling towards the window?

They are likely growing towards the strongest light source.

Rotate the tray or provide more even overhead light.

Should I leave grow lights on overnight?

There is generally no need.

A daily light period followed by darkness is suitable. Approximately 12–16 hours of artificial light is a useful starting range.

How far should a grow light be from microgreens?

It depends on the light.

Follow the manufacturer's recommendations and watch the crop for stretching, bleaching, heat stress or other signs that the distance needs adjusting.

Can I use a normal LED light?

Potentially.

If it provides enough usable light with good coverage, an ordinary LED can support microgreen growth.

A distant household ceiling light, however, may not provide sufficient intensity.

Do I need an expensive grow-light setup?

No.

Many people can grow microgreens successfully with natural daylight or relatively simple artificial lighting.

More specialised equipment becomes useful when you want greater consistency, larger growing areas or year-round production independent of available window light.

Getting Microgreen Light Right

Microgreens don't need complicated lighting, but they do need enough consistent light after germination.

A useful sequence to remember is:

Germinate → blackout where required → uncover → provide bright light → monitor growth → harvest.

When using grow lights, approximately 12–16 hours per day is a useful general starting point.

When using natural light, choose a bright location and watch the crop for stretching, pale growth or strong leaning towards the window.

In Australian conditions, don't confuse more sunlight with better growing conditions. A tray sitting against hot window glass can receive plenty of light while simultaneously becoming too warm.

Light works together with temperature, moisture and airflow. If one changes, you may need to adjust the others.

For the complete growing process, see How to Grow Microgreens at Home in Australia.

To understand when seedlings should leave blackout and move into light, see Microgreen Blackout Explained: Why, How & How Long?.

Because light, temperature and water requirements are closely connected, also see How Temperature Affects Sprouts & Microgreens and How to Water Microgreens: Misting vs Bottom Watering.

Browse the OzSprout Microgreen Seeds range for individual crop growing instructions.