How To Plant In A Greenhouse

February 28, 2020Katie
How to Plant in a Greenhouse -Dishin & Dishes

The advantages of a greenhouse far outweigh not having one. But many people are intimidated by the whole process so today I am going to show you how to plant in a greenhouse.

If you need a starter plan for a greenhouse, see how we built ours by clicking here  for Part 1 and clicking here for Part 2.


It’s simple, therapeutic, rewarding and will save you TONS of money from having to buy plants full price at a nursery.

A packet of seeds can cost $1-$3 and sometimes you get 30, 50 or even 100 seeds. A pepper plant usually costs around $3-$4 at my nursery, so you can see how if I plant 30 pepper seeds at $2 a seed packet plus a few bags of soil, or buying 30 pepper plants for $90, well….my greenhouse has paid itself back MANY times over.

I always start my tomatoes and peppers in my greenhouse in mid-january. Here in Oklahoma, we can get 90º plus temperatures starting in June or July. When day temperatures exceed 85°F and night temperatures exceed 72°F, tomato flowers will drop off the plants and pretty much the same with peppers.

We combat this by getting a head start on them by planting them in the greenhouse really early. By early April when we put them into our raised beds, they are already flowering and we have a few baby tomatoes and peppers! By the time the heat hits we get a crop of both tomatoes and pepper and then another one after the heat leaves us in September through November.



You’ll need a few things to start growing in your greenhouse in winter months:

*A safe heater. Or two.

Heater greenhouse

Please keep in mind to keep your heater away from anything combustible. Also make sure you get a safe one. Gardening friends I know also use a propane heater but we just use an extension cord and use electric. Most of the time the big one on the right is fine but on extremely cold nights we use both.

We also bought this little guy.

*A Bluetooth Weather Sensor

ECOWITT WiFi Weather Sensor Smart Sensor

The ECOWITT WiFi Weather Sensor Smart Sensor.

Coming in at around $35, it’s totally worth the hassle for me to keep running out and checking the temperature in my greenhouse. It attaches to your wifi and your phone and you can view the temperature and humidity at night from the warm confines of your home. You can also view it from away from home on the web.

And speaking of temperature…

*A Thermometer

greenhouse thermometer

You know, just to make sure the fancy gadget is working and you can see it at a glance each time you go into your greenhouse. I try to keep my greenhouse above 70º at all times but experts say the ideal temperature inside the greenhouse should be about 80 to 85 degrees Fahrenheit.

If the sun is out on a 50-60º day, my greenhouse can climb up to 100º by afternoon so keep an eye out for changes! Pay attention to what your weather will be and plan accordingly.

*Seed or Plug Trays – I get this type with 72 cells in each. I’ve re-used these each season for 4-5 years and am still using with no difficulty or breakage. They are harder plastic and more durable.

I do NOT like these as they are flimsy and break easily after one season.

seed tray plugs greenhouse

*Clear plastic lids.

greenhouse seed tray lids

These aren’t totally necessary, but they keep your watering days down and help your seeds germinate faster. The water tries to evaporate but drips back down on the plants, keeping them moister for germination. They also help keep the plants insulated and therefore your greenhouse doesn’t have to be kept so warm all the time. It just adds another layer of protection.


Here are some tips for planting in your seed trays.

*Find a Good Planting Mix – I get a large bag from my local nursery.

Make sure your seed cell trays are clean. Using last year’s trays sometimes can lead to fungus or other issues in your trays. Click here to learn how to disinfect your trays.

Fill each tray cell to the top. I leave a giant scoop inside my bag of soil which makes this pretty quick to do and then scrape it with my hands to all sides of the tray to level it across the cells.

Sorry i didn’t take a picture of the filled this one will have to do with baby plants!

Next water the soil in well, as in, where it’s running out of the bottom of the tray. I prefer to have my soil pre-moistened before planting seeds so as not to bombard them with water and risk them floating into the next cell etc.

*Get a Good Fine Sharpie – This serves two purposes -the first being to use the end without the cap to poke holes in each seed tray (however deep your seed instructions say.)

Get Good Markers -I usually get some like this at my local nursery. I’ve also used popsicle sticks but I like the shorter ones so that my lids will fit. garden markers


Start with your first packet of seeds. Label each plant marker so you’ll clearly be able to tell what they are (keep to the top as the bottom will be in the soil). I usually just do one for the end of the row for each type of plant. I don’t do every row but just start the new marker at each new plant.

How to Plant in a Greenhouse - Dishin & Dishes

Plant Your Seeds – Stick one seed in each hole you’ve made in each seed tray cell. Plant one more row than you think you’ll need. This way if some seeds don’t germinate, you’ll have enough.

How to Plant in a Greenhouse

Using your fingers gently cover each seed with the damp soil patting it down but not too much.

You can lightly water again. Don’t use the water too harshly so as not to wash out the seeds!

Cover them with your tray lid, step back and feel like a million bucks! I don’t know what is so rewarding about this process but I love it. Once I learned how to plant in a greenhouse, it became truly addictive.

I visit my little trays every day just watching for a tiny sign of life. And then each day you see them grow bigger.

Greenhouse Plants -Kale

After they get solid with 4 leaves, it’s time to transplant them into containers.

That lesson will be coming soon!

How to Plant in a Greenhouse - Dishin & Dishes


  • W Properties

    March 5, 2020 at 5:24 am

    Thanks for this guide. I've been planning to build our own greenhouse at home and have homegrown plants instead of always buying at a grocery store. This would save me a lot of money.
    1. Katie

      March 5, 2020 at 4:33 pm

      So glad you found it! And I can help!
    2. Katie

      January 30, 2023 at 11:53 am

      You're welcome! Hope it all goes well for you and you take the leap!

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