starting seeds outdoors mini greenhouse

How to Plant Seeds in a Mini Greenhouse

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A mini-greenhouse helps to maintain warm temperatures in the soil and air, which aids in seed germination. Most mini-greenhouses come with pots or a plastic tray that holds the potting mix and a clear plastic covering that allows in light and helps the soil retain moisture.

These greenhouses are most often used indoors, according to an article from the Seed Collection, although you can also set them outside during sunny weather if the temperature is above freezing. The clear covering continues to allow light in after the seeds sprout, creating a greenhouse environment during the early plant growth period.

Prep the Soil Mix

Fill the greenhouse planting tray or seedling pots, depending on the design of the greenhouse, with a sterile potting mix. Fill the water tray with 1 inch of lukewarm water and set the soil tray or pots inside it. Allow the soil to absorb the water for at least 30 minutes or until the soil surface becomes moist; then empty the excess water from the drip tray.

Sow the Seeds

Sow the plant seeds in the moistened soil mix at the depth specified on the seed packet, which is usually a depth that’s approximately twice the width of the seed. Plant two seeds in each pot or planting cell, or sow the seeds 1 inch apart in rows that are spaced 1 inch apart in trays or flats. Mist the soil surface with water to moisten it after planting if necessary.

Cover the Tray

Set the greenhouse cover on top the tray and place the mini-greenhouse in a location that receives bright, indirect sunlight and where temperatures are between 65 and 75 degrees Fahrenheit. The cover helps retain moisture in the soil mix so it doesn’t need to be watered until after germination.

Prop the Cover Up

Prop open the greenhouse cover after the seeds begin to sprout to allow condensation to dissipate. Use a small stick or pencil to hold one end of the cover up.

Water the Seedlings

Water the seedlings when the soil surface feels dry. Pour water into the drip tray so the soil soaks up the moisture from the bottom and the seedling leaves don’t get wet, which can lead to fungal disease.

Remove the Cover

Remove the greenhouse cover completely before the seedlings grow tall enough to touch the plastic.

Things You Will Need

Planting tray or pots

Sterile potting mix

Small stick or pencil

Disposable aluminum baking dishes that are sold with clear plastic covers make excellent homemade mini-greenhouses. Use small individual planting pots or cell planters to hold the soil and seed inside.

As an alternative, an article published by the Illinois Extension notes that you can sow your seeds in winter using a translucent 1-gallon plastic jug as a mini-greenhouse: Clean the jug, punch drainage holes in the bottom and cut around the circumference about halfway between the top and bottom, leaving 1/2 inch uncut to serve as a hinge. Fill the bottom half with moistened potting mix, sow your seeds, tape the top down and your mini-greenhouse is ready to take outside.

Some mini-greenhouses consist of shelves covered in clear plastic for use indoors or out. Vent these types of greenhouses by opening the door or the installed vents. If you use these greenhouses outdoors, place a thermometer inside and vent the unit before temperatures climb above 80 F as high temperatures can kill seeds and seedlings.

How to Plant Seeds in a Mini Greenhouse. A mini-greenhouse helps maintain warm temperatures in the soil and air, which aids in seed germination. Most mini-greenhouses have a plastic tray that holds soil or pots and clear plastic covering that allows in light. These greenhouses are usually used indoors, although you …

Starting Seeds in the Mini Greenhouse

I’m having some fun experimenting with the (affiliate link… read more) Gardman R687 4-Tier Mini Greenhouse which I recently purchased from Amazon. It’s an inexpensive shelf system with plastic covering that serves as a mini greenhouse on my driveway. I decided to purchase this system this year so I could try getting seeds, bulbs and tubers growing a bit earlier in the season but without having to have it all happen indoors. Today’s project is starting seeds in the mini greenhouse. Come take a look with me!

Building The Mini Greenhouse

The greenhouse rack arrived from Amazon in a small box and was fairly lightweight.

I unpacked the box onto the driveway and found it to be a very simple project to put together.

In no time at all, the mini greenhouse was assembled and ready to receive plants.

I was a little bit disappointed to realize that the rack didn’t come with wheels. My plan was to roll the rack into the garage at night, and roll it outside onto the driveway in the morning. But, no wheels. So I’m either going to have to unload and reload the shelves daily, or I’m going to have to build some sort of rolling cart. Or I could leave the plants out on the driveway inside the plastic overnight, but I don’t know how warm the plants would be overnight without getting a thermometer and testing it. Which I’ll be doing as soon as I can.

Starting Seeds

I filled up five flats full of cell packs and small containers with planting medium, and got to work sowing seeds. I had some Columbine ‘Harlequin Mix” seeds leftover from last year and did those first. The seeds look like strawberry seeds… or like little fleas.

I planted some lunaria (common name Money Plant). This plant is all over our neighborhood with pretty purple flowers and later the white translucent seed pods. I want some in my yard too!

And some Forget-Me-not. I have heard that this becomes invasive in some environments. But I’ve tried this plant several times in several different homes and have NEVER gotten it to grow, much less spread. we’ll see what happens here.

Foxgloves. Love these. I did get about 6 or 8 of these plants to grow last year, and they survived the winter ok. Because they’re biennials, they didn’t flower last year of course. I expect they’ll be sending up their flower stalks sometime soon. So I’m starting these seeds again this year, for next year’s bloom. With any luck, this year’s flowers will shed seeds into the garden for self-seeding, but I’m not taking any chances.

Last year I gathered seeds from some primroses, and sowed some of those today.

And there are several columbines that I gathered seeds from last year, and planted them up today. Some of them had hundreds of seeds, while others had only a couple dozen. I haven’t seen any of the columbines come back yet this year in the garden, so having these seeds is a nice insurance policy.

And marigolds. Of course, marigolds. Last year I saved about 50 times more seeds than are shown here, saved from one of last year’s plants. I will NEVER be able to use all the seeds I saved… do you want some?

I potted up 18 gladiolus ‘Plum Tart’ which I purchased at the Dollar Tree, of all places. They had packages of 6 or $1. I figured, why not?

In anticipation of putting some seedlings into the vegetable garden, not just seeds, I planted up a dozen small pots of green beans,

and nine pots of cucumber. Hope they do well and give me a good head start on the garden, without the cost of buying seedlings.

And now we wait

I watered everything, and put the flats of seeds into the greenhouse and zipped it up. Even on this cold, blustery, cloudy day, the plastic was quickly covered with condensation. And when I unzipped the plastic, it was noticeably warm inside the mini greenhouse.

I’m definitely going to invest in a thermometer for inside the rack. That way I’ll have a good sense for how warm it’s getting, and will be able to monitor it for a while. It’s a good thing I am at home each day – ahh, the retired life! – and can check on things and hopefully keep the environment just right.

Do you have any experience with a mini greenhouse like this? Or with a full sized one? Or anything like this? I’m new to this whole thing and would love to learn from your experience.

Have you started sowing seeds for your garden yet? How do you do it? Please drop by the comments section and share your thoughts with me

Get a head start on your flowers and vegetables by starting seeds in the mini greenhouse. Come take a look!