Greenhouses provide two essential things all seeds need: sunlight and humidity. You can create the same conditions indoors on a shoestring budget if you get a little clever with your approach. Soaking the seeds overnight might be part of the planting instructions on the seed packet. Read the instructions carefully and do not skip and steps for the sake of expediency.
Greenhouse in a Bag
This is a great hands-on growing project to do with the kids – and it is not the least bit messy. Simply put up to three seeds in a quart freezer bag with well-dampened cotton balls. Press the bag closed and hang it in a window that gets decent sun throughout the day.
The moisture created by the damp cotton balls will generate the humidity needed to get the seeds started. Once they begin growing, they can be transplanted into a quality soil in a container to process into plants. The container can be kept indoors permanently, depending on the plant you are growing, or transplanted outdoors once the danger of frost has passed.
Photo: my grandchildren are growing green bean seeds in their greenhouse in a bag. We cut a house shape out of construction paper to decorate the hanging bags.
Not only do humidity domes produce the 68F to 77F degree temperature seeds need to thrive, they also give you the chance to upcycle some materials that otherwise would have been deemed junk. Any plastic container with a clear top can be used to make a humidity dome for starting seeds. A salad container, lunch meat container, or container rotisserie chicken comes in from the supermarket, will work great.
How to Make a Humidity Dome
1. To potentially increase the heat generated inside the humidity dome, spray-paint the bottom portion where the seeds will be placed, black. If you container is deeper on top than bottom, spray paint the portion of the top that will be at dirt level, black.
2. Put good quality dirt in the humidity dome.
3. Moisten the dirt.
4. Plant you seeds as directed (depth and spacing) on the package.
5. Place the humidity dome near a natural or man-made light source. Seeds require a lot of light or they will become feeble and grow in a thin and spindly manner.
6. Transplant the seeds to a large container without a dome or outdoors, when necessary.
More detailed, step by step instructions with diagrams here.
There is no need to spend several hundred dollars for a commercially manufactured humidity grow tent. You can make one yourself for no more than half the cost. A baking wire rack shelf unit or a free-standing metal storage shelf unit (the kind you probably have a few of in your garage or prepper pantry) make sturdy bases for grow tents.
The grow lights attached above the shelves allow you to control both the temperature and the humidity in the tent with ease. The heat lamps often used in poultry brooders generally increase and maintain the humidity levels inside the grow tent quite well. These are the kinds of light I used when we rescued desert tortoises that required a high humidity environment. A hygrometer mounted inside the grow tent will permit you to keep a close watch on fluctuating humidity levels.
Use clear plastic if the unit will be placed next to a window that gets good sun. If no such space exists in your home, use black plastic on one to three walls to better reflect the rays from the grow lights.
Grow Tent Tips
• If you use a wire shelf rack, only one set of grow lights will typically be needed to provide light and humidity of all the shelves filled with growing seeds. If a metal shelf unit is used, the light from a top-only source will not be able to filter light to the racks below, making it necessary to purchase and attach grow lights for each shelf label.
• If necessary, put a humidifier on the bottom shelf to increase levels inside the tent on an as needed basis.
• Putting a fan on the bottom shelf may also help to better circulate the air, heat, and humidity, so each seed receives the maximum benefit.
More info on how to make the growlights here.
CD Case or Picture Frame Greenhouses
These mini greenhouses will give a litter extra color and flash anywhere they are placed. You simply use the clear plastic part of the CD cases, and front frame of picture frames, to make a traditional greenhouse shaped home for seedlings.
Use hot glue, E600 (my personal holds everything but water together glue) or super glue to affix the CD cases or picture frames in a house shape – except for one section that will function as a flap so you can water the growing groceries.
Put the seeds in quality and moistened dirt inside individual containers and place them on the floor of the mini greenhouse.
Plastic Bottle Greenhouses
This may be the simplest and cheapest of all ways to get your seeds growing indoors. Cut the top off of a plastic pop or water bottle and toss it in the recycle bin – keep the bottom. Plant your seeds in a small individual container and place the dome-shaped bottom section over top of the individual seed container.
These mini greenhouses can be placed on a tray to keep them together and on top of a shelf, chest of drawers, or table that is located next to a window with good light. They can also be sat individually in windowsills for space-saving purposes.
It is also possible to cut the same plastic bottle in half and put the seed in the bottom dome portion and tape the top of the bottle back on to churn up heat and humidity. Some of my homesteading friends who use this method leave the cap off of the bottle but others drilled several small holes in it to prevent humidity and heat from getting too high and scorching the seed.
Vertical Seed Bins
The beauty of this seed-starting method is the absence of a need to ever transplant the growing crop. Mount a rain gutter or piece of PVC pipe to a wall that gets good sunlight. What, that will look really, really ugly? Yes, it will…but only if you don’t infuse a bit of rustic creativity into the project.
The rain gutter or PVC pipe can be painted, covered in burlap, or decorated in any other method that blends well with the decor on your homesteading survival retreat.
If using PVC pipes, you will need to drill a hold in the top of the pipe that is large enough to accommodate the mature plant the seed will become. The PVC pipe seed starting system could be detached from the wall once the plants begin to grow, turned so the opening hole is now facing sideways, and attached to an exterior wall for outdoor weed-free growing.
While seeds are being cultivated, cover the chosen vertical gardening container with plastic kitchen wrap or clear plastic sheeting to create humidity.
This PVC vertical gardening container has holes for plants on all sides because it was not used for seed starting, but you can still get the idea of how the pipe could be quickly transformed from seed starting indoors to an outdoor small-space crop container.
Popsicle Stick Mini Greenhouses
Use any wood or plastic container you have hand to start your seedlings. Save or buy enough popsicle sticks (or thin dowel rods) to serve as supports for the plastic kitchen wrap you will place over the containers to form a tent shape cover.
The plastic wraps must be pulled securely over and around the container and pressed against the bottom to keep in the heat and humidity. You will likely have to change the plastic kitchen wrap a few times as the seed grows because it can tear when being tightly wrapped, removed, and replaced tightly once again, around the base container.
Seed Starting and Transplanting Tips
1. Using soil less peat moss and equal parts of both perlite and vermiculite when starting seeds, for best results. This mixture generally works better than potting soil because it allows for more oxygen flow.
2. Mix the peat moss, vermiculite, and perlite with enough water to moisten it before putting it into the seed containers.
3. Use a squirt bottle and mist the seeds with water instead or pouring water directly onto them. The force of pouring water can dislodge the seeds or flood their tiny and still emerging, roots.
4. Depending on the temperature of your home, the plastic coverings over the seeds can be removed once above dirt level growth appears.
5. Once the seeds grow at least two pairs of leaves, they can be transplanted. When transplanting the seeds, mix in some compost and/or potting soil.
6. Transplanting is a traumatic process for the seeds. It is often recommended to keep them out of intense or direct sunlight for a couple of days after transplanting.
7. Always “harden” the seeds or young plants before moving them outdoors. Approximately 10 days before relocating the indoor crops, take them outside in a shady area that has wind protection or a couple of hours each day. Move them closer to full sunlight and raw exposure to the elements a little bit each day.
8. Keep in mind that windy spring days and dry air can cause moisture loss in the soil. The young plants may need extra water after coming in from their day trip outdoors.
9. To continue the hardening process, about one week before their anticipated relocation, stop fertilizing them, if you have been engaging in that process.
10. It’s best to transplant seeds or young plants outdoors in the morning hours or on cloudy days to prevent overexposure to the sun.
11. If transplanting the young plants directly into the ground, soak the dirt around their new hole right after placing them inside.
12. Put some mulch on top of the transplant to help prevent moisture loss and to maintain at least a little bit of humidity during the transition period.