Seeds of Plenty - growing Tomatoes from seed

Growing Tomatoes from Seed - tips from a seed supplier

Dan’s Garden update

Welcome to the second edition of Dan’s Garden where I talk about what is happening at the Seeds of Plenty gardens and my process for growing tomatoes from seed. Today I wanted to follow on from the last edition and bring you up to date with what’s happened in the garden over the last 6 months.

The Harvest

In the last blog edition, I spoke about how we built our garden and what types of plants we were growing. As I mentioned, we grew dwarf tomatoes, some regular tomatoes, and a couple of capsicums last year with the intention of harvesting seed and selling it through our store.

All up, I planted about 50 varieties! This was way too many for me to handle, and whilst we did get some seed from a lot of the varieties, the amount of work involved in managing the plants and harvesting the seed from so many different varieties was huge. I won’t be doing that again in a hurry.

Managing the plants

Whilst tomatoes are mostly self-pollinating, they do cross when grown close together. To reduce the risk of crossing I netted all the plants. Making 40 different nets was a lot of work and it was time-consuming opening and closing the nets when pruning and harvesting.

I learnt that you can significantly increase the yield of tomato plants by vibrating the flowers which makes sense as this is what bees do in nature. Having 10 plants under one net made this easy as you could shake one plant and the net would shake the rest. Stimulating the flowers with an electric toothbrush is also another great way to get them to release their pollen and up the pollination rate. I gave this job to my kids and they had a great time doing this over the summer.

The great thing about growing Dwarf tomatoes is that they don’t grow very big and they require minimal pruning over the season. Most of the dwarf plants I pruned once or twice just to remove some suckers around the base of the plants. I only tied them once and in some cases, the plants didn’t need any tying at all. The few full-sized plants we grew needed a lot more tying and pruning. To keep the big ones under control, I tend to keep them to two main stems and trimmed off all the other suckers.

Harvesting tomato seed

With 50 varieties this was a very time-consuming process requiring a lot of organisation and diligence in order to keep the fruit from mixing. I was chief harvester but I had a lot of help with seed extraction.

There are a number of ways to get seeds out of tomatoes. Most large growers will process the whole tomato in order to get the seed out. The seed is about 0.2% of the whole fruit, so just chucking out the rest means a lot of wasted tomato. Rather than waste the fruit, I chose to manually extract the seeds from the tomatoes.

I enlisted the help of family and friends over the autumn months. Prior to the beginning of lockdowns, my dad and a friend of his hand-processed about 150kg of fruit over a 6 hour period. I then enlisted some close friends who would pick up the fruit from our front doorstep, take it home, process it, and then deliver back small containers of fermenting seeds.

They processed at least 150kg and I would have done another 50kg in my spare time. All up, it was a lot of work and a lot of tomato juice all over our kitchen. The payoff was that the tomatoes were put to use and we all have lots of delicious tomato sauce and tomato chutney this year.

Seed Extraction

By the end of autumn, I had harvested at least 4 times on average from each variety of tomato. This meant that after seed extraction I was left with over 200 lots of tomato seed that I needed to clean.

To remove the gelatinous coating from tomato seeds you need to ferment them for 2-3 days in a small amount of water. The good seeds will sink to the bottom of the container and then you strain off the waste until only the seeds are left. It took forever to process this many seed lots but in the end, it was satisfying to actually see the outcome of all the work.

After cleaning, you dry the seed. I did this in two stages. The first was an hour or two in a dehumidifier to remove most of the moisture. Then I used silica gel which finished drying the seed to around 7% moisture which is perfect for storing the seed long term.


In terms of the amount of seed we got, I was a little disappointed but chalked this up as growing tomatoes from seed learning experience. In total, we collected a usable amount of seed from about 40 of the varieties and we got around 250g of seed which is close to 100,000 seeds. This year, we will have the same number of plants with fewer varieties. In the longer term, we will look externally for people to grow our seed and we will concentrate more on trailing seed varieties.

Where to now?

Monthly blog updates from our garden are on the list of goals.

We had a busy autumn at Seeds of Plenty due to Covid-19, so it’s looking a little neglected. But on the positive side, we do have a bit of money to invest in improving the garden now. I hope to build some new beds over the next few months. I also have a whole lot of exciting varieties to try this year and will be starting these indoors in late July. So stay tuned to see what tomatoes we grow from seed this year!

Happy gardening everyone and hope you learnt a thing or 2 about growing tomatoes from seed.


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