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Cultivating Gardens from Seed Successfully

March 07, 2012
love lies bleeding grown from seed

Gorgeous Love Lies Bleeding grown from seed in 2011 using the methods illustrated below

If you’re starting seeds in a greenhouse planting tray & lid,  be sure you know when to keep the lid on and when to take it off. (I’ve provided a photographic timeline later in this post, so skip ahead if pictures are better for you than words.) Lids help keep in moisture and heat, which is a good thing for germinating seeds. Lids can also intensify light on the soil, which is also a good thing for helping warm the soil. But too much of a good thing can be bad.

Once the seeds germinate and send shoots above the soil, its time to begin opening the lid a bit to ventilate. This helps some of the accumulating moisture evaporate, so be sure to check the soil often in case it needs watering. And, getting that bit of ventilation going will also help keep down fungal disease; even the smallest bit of airflow can make all the difference.

Then, once the seedlings begin to get a little height, be sure to remove the lid completely. This will give the young plants room to grow upwards. Ventilation will also be increased. And, shortly, you’ll be potting the young plants into bigger containers or moving them out into the garden.

Following is a visual guide through the various steps I find work really well:

Closed Greenhouse Tray Incubates Seeds

This tray was recently seeded. Keeping the lid shut keeps in moisture & heat.

Peeking under the lid

Just a quick peek under the lid shows soil cells with labels tucked into each. If the seeds have begun to germinate, everything’s still happening below the surface.

Seedlings emerging

Once the seedlings emerge, I insert the tags upright. The written information faces out on tags placed on the outside edge of each cellpack. Then, the lid is placed over the plants, resting on the top of the tags. This creates about 1/2″ break that allows air to enter and flow, but some heat is still retained.

The Lid is removed

Once the plants are growing strong, I remove the lid altogether. The trays are still protected from the elements, whether they’re grown under lights indoors or in this case inside the greenhouse. At this point, I’ve begun separating the seedlings and potting them up.

Potted up seedlings

The seedlings are then carefully separated and planted into 4″ pots. Each tray of seedlings gets a new tag that includes the date they were seeded, the date they moved into 4″ pots and a note on where I got the seed. Later, when they’re a bit stronger, the entire tray will move to the vented cold frame to harden off more or they go directly into the ground under the hoop houses. Into the ground is where they’ll all end up — if they make it that far!

Note: Seed & starts shown here may have originated from seed we purchased &/or seed provided for test growing by Renee’s Garden Seeds, Irish Eyes, Botanical Interests, friends, and others. We have received no compensation from suppliers for this post.


  1. […] Robin Haglund shares at Garden Mentor […]

  2. Jim says:

    How do I get my indoor started tomato plants to look like the dark green ones you can buy in the local greenhouses. Mine are fine started in starting mix but just don’t have that dark green to them they are light green?

  3. Jim,

    There are many reasons yours might not be greening up. Are they getting enough light? Are you giving them any fertility/potting them up after they germinate. Without knowing more, it’s hard to say what’s happening.

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