To Wrap or Not to Wrap? The Debate on Covering Seed Trays with Plastic

Plastic that looks like plastic adds its own surreal touch to any scene. I use sheets of food wrap to cover plugsheets trays until the seedlings push up above the surface. The plastic holds in heat and keeps the seedling mix moist, both of which the seeds definitely like. As soon as the seedlings emerge, off comes the plastic. Time to let the air flow. I reuse new sheets of wrap for a whole season. With use, they lose their clinginess and are that much easier to handle. The little things add up!.

Starting plants from seeds can be rewarding, but it also involves some tricky steps. Getting seeds to successfully germinate indoors requires close attention to factors like moisture, temperature, and light. One common question for seed starters is whether covering trays with plastic wrap helps or hurts seedling success.

Plastic wrap, also called cling film or saran wrap, is often recommended to cover seed trays in order to retain moisture during germination. But some experienced seed starters warn against using plastic wrap. So what’s the real story – to wrap or not to wrap? Let’s explore the pros and cons of this practice to help you decide.

Why Cover Seed Trays with Plastic Wrap?

Here are some potential benefits of tenting seed trays with plastic wrap:

Retains moisture – Plastic minimizes evaporation to keep seed starting mix evenly moist. Fluctuating moisture levels can cause erratic germination.

Increases humidity – Higher humidity from the trapped moisture benefits seed germination and sprout growth.
Protects from drying out – It’s easy to let trays dry out too much without plastic wrap, especially if you forget to check soil moisture daily.
Shelters from rain/watering – Direct water contact can shift seeds around and damage tender sprouts Plastic forms a protective barrier.

Provides warmth – The small greenhouse effect warms the soil and air temperature to enhance germination.
Prevents soil splash – Heavy watering can splash mix onto seedlings and compact the soil surface. Plastic wrap prevents this.
Keeps out pests – Pesky gnats, flies and other insects are blocked from laying eggs in the moist soil.

So in theory, plastic wrap sounds like an ideal way to coddle your seeds and give them the best start in life. But in reality, using plastic wrap also has some potential drawbacks.

Why Not Cover Seed Trays with Plastic Wrap?

Here are some of the downsides that come along with plastic wrap coverage:

Promotes mold and fungi – Too much moisture and humidity foster diseases that can harm sprouts.
Causes leggy, weak growth – Without airflow, seedlings stretch for light and become tall and spindly.

Traps excess heat – Temperatures can spike to detrimental levels, especially with no ventilation.
Leads to overwatering – It’s harder to tell when covered seed trays need watering.
Invites pests – Excess humidity and trapped heat also attract fungal gnats.

Causes soil to crust – Water droplets that settle on soil can form an impenetrable crust.
Requires ventilation – You must uncover daily for gas exchange once sprouts emerge.
Can stick to leaves – New sprouts and leaves are very fragile and plastic can damage them.

Hard to monitor – It’s difficult to observe seedling progress with trays covered in plastic.

As you can see, the drawbacks of plastic wrap often outweigh the benefits in real world application. Moderation and attentive care are key if using plastic.

Tips for Using Plastic Wrap on Seed Trays

If you want to try covering your seed trays with plastic, here are some best practices:

Use very thin plastic wrap – Thicker plastic doesn’t allow for air exchange.

Ventilate twice a day – Lift plastic to provide airflow once sprouts emerge.
Remove at first true leaves – Cut plastic away carefully when seedlings are very small.
Support plastic so it doesn’t touch – Prop up plastic on sticks or skewers to prevent damage.

Watch soil moisture closely – Check trays daily and resist overwatering.
Control humidity and temperature – Don’t enclose trays fully, and avoid direct heat or sun.

Alternatives to Plastic Wrap for Seed Trays

Here are some other options if you don’t want to deal with plastic wrap:

Dome lids – Clear plastic domes designed for seed trays allow airflow and are easy to vent and monitor.
Cell packs – Maintenance is easier with individual cell packs that inhibit drying out.

Humidity domes – Mini greenhouses with vents supply ambient moisture without excess humidity buildup.
Misting – Frequent, gentle misting maintains moisture levels without excessive water.
Germination mats – Heated mats warm roots for better germination without spiking air temps.

Grow lights – Better than relying just on ambient light, grow lights prevent stretchy, leggy growth.
Bottom heat – Warming the roots only, via cables under trays, avoids overly hot air.
Soil coverings – Materials like vermiculite, coconut coir, or milled sphagnum evenly maintain moisture while allowing air exchange.

To Wrap or Not? Factoring In Your Conditions

The decision on whether to use plastic wrap depends partly on your growing environment and care regimen.

If your home is cool with low humidity, plastic may help compensate for a dry atmosphere. But in a naturally warm, humid house, it could easily cause problems.

The amount of time you can devote to uncover, ventilate, and monitor covered trays is also key. Careful growers may have success with plastic wrap, while busy seed starters are better off with alternatives.

It’s fine to experiment with plastic wrap on a portion of your trays while leaving some uncovered for comparison. Just stay observant and don’t let perfect become the enemy of good when it comes to starting seeds.

While plastic wrap has some benefits for seed starting, it also requires moderation and diligent oversight. For many home gardeners, skipping the plastic in favor of other moisture-maintaining options leads to better results with less hassle.

Follow basic best practices for seed starting, and don’t agonize over every last detail. Your main goals are gently consistent moisture, good drainage, warm soil temperatures, and adequate light as soon as sprouts emerge. With or without plastic wrap, focus on providing those key elements for success!

Covering with plastic wrap vs without/ which will germinating parsley seeds best

FAQ

Should I put saran wrap over seeds?

Seeds need to be moist while germinating but not too wet. Our best tip is to keep those trays covered with clear plastic wrap or a humidity dome until your seeds germinate—especially if using heat mats! So critical.

Should you cover new seeds with plastic?

To speed germination, cover the pots with plastic wrap or a humidity dome that fits over the seed-starting tray. This helps keep the seeds moist before they germinate. Once seeds have germinated and you see leaves, remove the cover to allow air to circulate.

Can I cover seeds with cling film?

To maintain an even temperature and keep the soil moist, it’s a good idea to cover the soil with a clear piece of plastic. A bespoke propagator will come with its own clear plastic lid, but you can use cling film, old freezer bags or any clear plastic bag. Use sticky tape or an elastic band to fix it to the pot.

Do seeds need a plastic cover?

But you only need plastic wrap, an item you probably have in your home already. A cover works to keep the soil moist, helping your seeds sprout. In general, the first one to two days are when you need to focus your initial attention, helping your seeds to properly germinate. But what seeds do the best with a plastic cover?

Do I need to cover my seeds?

The answer is yes, it’s recommended to cover your seeds to help them germinate. But you only need plastic wrap, an item you probably have in your home already. A cover works to keep the soil moist, helping your seeds sprout.

Should you cover seed trays?

Covering newly planted seeds can aid the germination process by keeping the soil more evenly moist. Seeds sown in seed trays do best with clear plastic domes or wrapping while seeds sown outside benefit from a light layer of mulch or straw to keep the soil from drying out too quickly in the sun.

Can you plant seeds with plastic wrap?

Plastic wrap can be helpful when you’ve just planted your seeds, but it’s a temporary solution only. As your seeds begin growing, they’ll send their radicles into the soil and their cotyledons towards the light.