One little seed starting trick I have in my bag of gardening tricks is to start seeds in plastic cup greenhouses! I shared a picture of this about 2 weeks ago on my Facebook page and I thought today I would share with you the progress of the seedlings. This is an easy and amazing way to grow virtually any plant from seed. Best of all it’s very inexpensive!
How to Start Seeds In Plastic Cup Mini-Greenhouses
Starting seeds in plastic cups is a very easy way to start some seedlings. Just find two plastic cups (a Solo style plastic cup), one of which must be clear to allow light through. You can choose clear plastic cups or solid plastic cups for the bottom but for the top you need to have clear plastic cups. The plastic cups will cost you less than $3 or could even be free if you collect them after a family gathering or party. If you are re-purposing the cups make sure they are cleaned before you use them. If you are planting seeds in clear plastic cups you may be able to see the root systems for better.
What You Need for Plastic Cup Mini-Greenhouses
- 2 Plastic Cups per Variety of Seeds (At least one must be clear)
- Seeds
- Seed Starting Mix
- Water
- A Little Tape to hold the plastic cups together
Fill the bottom cup with a seed starting mix and water. Put your seeds in the cup and cover the seeds with an appropriate depth of soil then add a little bit more water. Don’t add too much water – we don’t want the seeds to rot. Cover with a clear cup and tape the sides.
Once seedlings have sprouted you can take the top plastic cup off. When you do take the top off be sure to monitor the moisture daily. Drying out at this stage is very bad for the seedlings. Likewise don’t add too much water as you can drown the seedlings which is just as bad.
Should you add holes to the cups?
A lot of people ask about putting holes in the bottom of the cups. I have found that I really don’t need drainage holes with this method. I’m very careful about over watering and if I do accidentally put to much water in the cup I just drain it off. I’ve found that my plants grow so quickly that they consume the water very fast making the holes unnecessary. Keep in mind that once these plants are germinated you will need to remove the top which will allow the water to evaporate. The plastic cups are only a temporary location and will get transplanted very soon into the next stage.
If you want to add drainage just poke a few holes in the bottom cup and use an extra cup (a 3rd one) to catch and hold the overflow of water. It may help to add something as a small spacer in between the two cups.
Transplanting
When the seedlings have grown their first set of true leaves you can transplant the plants to individual pots. You can grow a lot of seedlings in a very small space with this method as long as you don’t leave them too long in the cups. If they get too large the roots will intertwine and you may have difficulty in separating them. Remember the plastic cup method is to help with germination not to grow the plants for a long period of time.
The Seedlings Need a Good Light Source
Make sure there is a good light source for your seedlings. It could be a grow light or a very sunny window for the plants to use once they are germinated. Some plants need light to germinate so for them don’t cover them with soil or if you do do so lightly. Your seed package should have the specific seed starting instructions for that plant to follow. Be sure to read those seed starting instructions and help them get a great start!
Why do Plastic Cups work So Well to Germinate Plants?
The plastic cups are essentially terrariums that keep the moisture inside for the seeds to use while germinating. Consistent moisture is absolutely the most critical thing for successfully germinating seeds.
Can you Reuse the Plastic Greenhouse Cups?
You can reuse the plastic cups over and over again to start lots of seeds just make sure you clean them between uses to prevent disease contamination from different batches of seedlings.
Seed starting doesn’t have to use fancy equipment, just think outside of the propagation box! These plastic cup greenhouses are my favorite method of seed starting. What containers have you used for seed starting?
Here’s How I Start My Seeds In Plastic Cup Greenhouses
If you watch the seed starting video you will notice that I am using colored plastic cups for the bottom and only using the clear cups for the lids.
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Hello Dave! thanks for the idea! I´m making a small greenhouse at home and Iam starting some seedlings,we are finishing our summer here,I hope I can have some vegetables for the winter. besos. Lilián.-
Nice job, Dave! I continue to use my milk jug greenhouses. This year I have jacks-in-the-pulpit seeds "out there!" Hope they grow!!
Hi Dave
That's a nice little tip for germinating seeds.
I grow my tomatoes hydroponically in a polytunnel – in the UK the weather isn't great for outdoor tomatoes – so tend to use the rockwool starter cubes (see http://www.hydro-industries.com/2013/03/hydroponics-diary-germinating-tomato-seeds-in-rockwool/ for details) but I have also been thinking about how to germinate some of our outdoor vegetables using your method – such as runner beans.
I have been using recycled spinach and lettuce containers as well as plastic clamshells that have worked great. I should have used this method before.
Thanks for sharing your success!