One Way to Increase Yields Up to 50%
There are quite a few ways to significantly increase the amount of food that you can harvest from a small garden. I describe ten of them in my free course. But I now have another one:
Start your transplants in larger containers – give them double or triple the amount of soil that they usually grow in. Then plant them into your garden long before they even have a chance to think about becoming root bound.
This helps in a couple of ways:
1) Larger containers maintain a more even moisture level between watering, which helps your plants to grow more quickly and vigorously.
2) Larger containers will let your seedlings reach transplant size well before their roots start to feel constrained by the size of the container.
Many gardeners and nurseries grow their cabbage-family transplants in small containers, such as 1.5″ to 2″ wide. I have, too. But I just found out this year how badly that can affect my plants throughout their entire lifespan. They don’t have to actually become root bound in order to have their potential growth stunted.
My sister and I started about 130 broccoli and kale plants for our early spring garden in 2014. We had a motley collection of containers to use, of different sizes and shapes. So, this was a perfect way to discover just how much using different size pots can affect plant growth and final yields.
The containers on the left were round, 3″ pots, 3″ deep. The containers on the right were square, 3″ wide, and 4″ deep. They held 2.5 times more soil.
The pots on the right side hold about 2.5 times the amount of potting soil than the smaller pots on the left. You can clearly see how much larger the plants are on the right side – even allowing for taller containers. Both sets of plants were started at the same time, and given the same soil and growing conditions.
While some vegetables produce small, slowly-growing seedlings that do just fine in small pots, most crops in the cabbage family (including broccoli, kale, tatsoi, etc) really thrive best if they are given a bit more soil and elbow room. You CAN grow these seedlings in small pots. Don’t think you can’t! But your plants will grow larger and faster, and produce more, when given bigger containers.
You can still clearly see the difference in the size of my kale, even after they have been growing in the same garden bed for several weeks!
These plants were initially raised in larger pots. They filled their section of the bed, and were 3″ taller than the smaller kale.
These kale plants were initially raised in smaller containers. They never caught up to the size of the larger plants.
The kale from the larger pots have almost completely filled their part of the garden bed, but the kale from the smaller pots still have a lot of empty space between the plants. All of these plants were spaced the same distance apart and treated the same way. Just slightly stunting your plants when they are young can have a life-long effect on their growth!
When it came time to harvest the kale, the plants from the larger pots were still 3 inches taller, and had more leaves. The smaller plants never caught up in size. And here’s the biggest difference in my bottom line:
When it came time to harvest and freeze the kale, the kale plants that were started in larger pots produced 50% more kale leaves by weight! I measured this by what we were actually able to put in the freezer, with the stems and stalks removed.
All of the plants were started and transplanted at the same time, and given the same soil and growing conditions. The only difference was the size of their containers.
Giving my young plants over twice as much soil to grow in when starting them as transplants encouraged incredibly vigorous growth that carried through their entire lifespan. Small pots stunted the young plants, and they were never able to catch up. As full-grown plants, they all looked just great, but there was a significant difference in their full-grown size.
Mind you, the “stunted” plants didn’t look stunted! They were as large as most transplants sold in nurseries. Their containers actually had more soil than many nursery-sold transplants have. And they were NOT root-bound, either. Most gardeners would have been thrilled with the size that these plants eventually reached – but they didn’t reach their full potential.
So, if you want the maximum harvest from your garden, it’s worth experimenting with larger pots for your transplants. So far, the best size for my cabbage-family plants seems to be about 3″ wide square pots, that are about 4″ deep. This holds 2.5 times more soil than smaller round 3″ wide by 3″ deep pots.
Hello Debra. I hope you are doing well. I know you have a chronic medical condition. I feel for you. At this time every year I come back to your blog to “refresh” my memory. After rereading this article I was wondering if there is a chart available listing your Seed Starting pot-size Recommendations similar to your Vegetable Spacing Recommendations chart? For example:
Tomatoes – 4″×6″
Kale – 3″×3″×4″ square
Parsley – 1 1/2″×2″ (I’m guessing)
Etc.
If not, it could even be added to your Vegetable Spacing Recommendations chart by adding another column?
With all your experience it would be so helpful not only time wise but financially because of not wasting seed starting mix.
Just a thought. Thank you in advance. Anne
That’s a good question, Anne, and a good suggestion. I’m afraid I don’t have that kind of detailed information available. I’ve shared on this website pot size suggestions for the vegetables that I’ve personally noticed a significant difference in production. I suggest doing an internet search for other suggestions, AND always experiment in your own garden. Start some in smaller pot sizes and some larger. Compare how well they produce in your garden. I wish you the very best!
Thanks Debra
This is good information. I will put this in my tool kit for next year ( My broccoli seedlings this year are in the ground already and were grown in 2″ x 2″ Pots). They look good but it would be great if they could be even better.
Keep up the good work.
Thanks, Joe! I know some people that have good luck using smaller transplant containers, but I think most people may have a better experience by testing out larger ones. Best wishes!
Amazing! I had read that you should save your money and buy smaller plants in smaller pots, because they’ll soon catch up with the big plants. Clearly, that’s not true.
Hi, Sandy! Well, it depends. If you plant a 6-foot-high tree that was grown in a 3 gallon pot, and also plant a 2-foot-high tree grown in a 1 gallon pot, the smaller tree will usually catch up in size with the larger tree pretty quickly – because the larger tree has become much more root-bound and stunted in its pot. However, some young plants are so small and slow-growing that giving them a large container when they are small won’t make much difference in their final growth.
Some vegetables like tomatoes and cabbage-family plants can grow incredibly fast and vigorously if given larger containers than normal. If I put my tomato seedlings into 1-quart containers, they can become quite large and develop flower buds by the time they are just 5 weeks old – and they take off like crazy as soon as they are planted in the garden. But putting a parsley seedling into a 1-quart container is a bit of a waste, as it can’t use all that soil by the time you would normally transplant it into the garden.
Thank you so much for sharing things like this as you learn them. I think this is one reason that gardening is so addictive: There are always ways to improve and more things to learn!
You’re welcome. You are so right, Nancy! I’m never bored with gardening, as I’m always experimenting with new things.