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Can You Cover Seedlings With Cling Film

Growing plants from seed can be most rewarding but also more challenging than starting a garden from purchased transplants. Issues often arise when growing from seed because seedlings are so delicate and require a perfect balance of light, warmth, and nutrients to thrive. Over the years, gardeners have come up with many methods and so-called hacks to help support seedling life indoors and outdoors. Some of these growing techniques may sound questionable to a more traditional or novice gardener. So what some gardeners want to know is can you cover seedlings with cling film?  

Yes, covering seedlings with cling film at the appropriate time in their growth cycle can help to maintain warmth & moisture, providing greenhouse conditions without an actual greenhouse. It’s imperative to know how to use cling film appropriately when covering seedlings to not negatively affect the seedling’s health and growth.  

Read on to learn more about using cling film, alternative options, and care for seedlings.

Using Cling Film Effectively

The same qualities of cling film that make it ideal for covering and preserving food can make it beneficial for covering seedlings. The cling film acts as a seal, holding warmth and moisture in while seeds germinate. This practice is beneficial to seedlings with longer germination times and for those that require sowing closer to the soil’s surface, causing them to be at a higher risk of drying out.  

Combining cling film with a heating mat and grow light can provide perfect greenhouse conditions for seedlings. When using cling film or any alternative coverings, it’s still important to remove the covering to water and monitor seedlings regularly. As soon as a seedling’s first leaves appear, you must remove the cling film, so the baby plant doesn’t rot from the moisture on the plastic or overheat.

Alternatives to Cling Film To Cover Seedlings

Most gardeners will find that even if not using cling film for covering seedlings, clear plastic alternatives such as freezer bags or humidity domes will work similarly. However, sometimes in a pinch, we must be resourceful and use whatever is on hand. Food packaging and lightweight cardboard or paper have been known to work to provide those greenhouse conditions for seedlings in the short term.  

Type of Seedling CoveringProsCons
Freezer BagsProvide a similar condition to cling film because of clear plastic.

Smaller containers can be placed fully in the sealed bag.  
Because freezer bag plastic tends to be thicker they are slightly less effective than cling film plastic.

Require more manipulation to effectively cover larger containers.  
Humidity DomeProvide more airflow for seedlings.

Can continue to be used as seedlings rise above the soil, with weaning to outside light, air and moisture.  

Provides easier access to water and monitor the seedlings.  
Seedlings can become conditioned to the dome and struggle when time to wean off.  

Typically humidity domes must be purchased and aren’t easily DIY made.  
Reused Food PackagingEasily found around the house in a pinch.

Most materials provide some greenhouse-like benefits to seedlings.  
Challenging to manipulate to effectively cover containers.  

Less effective than clear plastic options.  
Light Cardboard or PaperEasily found around the house in a pinch.

Provides some greenhouse-like benefits to seedlings.  
Challenging to manipulate to effectively cover larger containers.  

Less effective than clear plastic options.  

Moisture will affect its usefulness in long term situations.  

Additional Tips For Healthy Seedlings

Taking proper care of fragile seedlings requires more than keeping them covered during germination. There are essential steps a gardener must take through the planting, germination, and early growth process to ensure seedlings survive and thrive in these first few weeks of life.  

Planting Seedlings

While many techniques for producing healthy seedlings are constant regardless of the type of plant, the recommended depth the seed is planted does vary.

Some seeds require a hearty covering of soil to germinate, while others prefer to be sprinkled on the soil surface or provided a very light soil coverage. Developing a habit of always reading the information on each seed packet regarding planting depth and following those steps for each plant type will result in happier seedlings.  

Heating Mats

Heating mats are an ideal resource for growing seedlings in cooler temperatures. Often gardeners want to start seedlings before outside temperatures are warm enough to promote germination.

Heating mats can trick the seeds into germinating by providing consistent warmth and are advantageous for indoor seedling start setups. Combining heating mats with proper moisture and lighting will undoubtedly provide more opportunities for healthy seedlings. 

Lights

Grow lights are a helpful tool for seedlings and growing in popularity among at-home gardeners. When starting seedlings indoors, before outdoor temperatures are warm enough and sunlight hours are long enough, grow lights provide a timed UV light source gardeners can use to trick seeds into germinating before they normally would outdoors.

At-home grow lights differ in many ways, so it’s important to read the manual for the lights you have purchased to ensure you are using the appropriate settings to provide efficient light to your seedlings while also not scorching them.  

Soil & Nutrients

It is crucial to start seedlings in nutrient-rich soil for productive growth. Typically, seed starting soil can be purchased at any garden center and contains extra nutrients that keep seedlings healthy. If seedlings are showing signs of malnutrition, such as wilting or yellowing leaves, consider conducting a nutrient test of your soil and supplementing the soil based on those results.  

Moisture

Seedlings require more consistent moisture than established plants, but it can also be easy to overwater if not careful. Watering with a spray bottle or a hydration tray underneath your seedlings will provide consistent moisture without drowning them.

It is relatively easy to identify if seedlings receive too much or too little moisture. If the soil feels hard or dry to the touch, the seedlings need more water; they are receiving too much moisture if the soil feels soupy. Yellowing or droopy leaves can also be signs of too much or too little hydration.  

Final Tips For Seedling Care

This article mainly focuses on methods and techniques that assist in early care for seedlings. However, it’s essential to understand that as seedlings continue to grow, almost all plant varieties will require a period of hardening to the natural environment.

Hardening is the process of slowly exposing plants to direct sunlight, air, and moisture. The graduation of this process differs from plant to plant. For optimum seedling growth and mature plant health, follow guides specific to the variety of plants you are growing for effective hardening and successful gardening.