Growing San Marzano Tomatoes in Kratky Hydroponics – Update: Week 6

I just realised that I forgot to write a post for last week, oops. Sorry about that. Guess the jump of growth between the last post and this one is going to be significant. This post is going to be big (not just plant growth), but because I discuss edema, flowers and fruiting too.

Lets look back at week 4 growth:

San Marzano Tomato 1 Month, In Kratky Hydroponics
San Marzano Tomato 1 Month, In Kratky Hydroponics

I was so proud of how big they were growing… and how fast – each day seemed to produce another branch, another leaf, or another inch or two of height… little did I know that the plants would keep growing at such a speed, even two weeks later. I have created a monster; a gorgeous, hopefully soon to eat yummy, monster:

San Marzano Tomato 6 Weeks Old, Grown In Kratky Hydroponics
San Marzano Tomato 6 Weeks Old, Grown In Kratky Hydroponics

Its getting huge! We have two of the trellis supports already installed, and tonight I will be putting in the third. Thats a trellis each week…

The Curious Case of Edema

Would you believe that I have actually been cutting branches off? We’ve actually been having a problem with how fast this plant is growing. So fast that it’s actually becoming a serious problem and risk, for the plant itself.

Edema on San Marzano Tomato Plant Leaves
Edema on San Marzano Tomato Plant Leaves

See those little green spots on the tomato leaves? That’s edema. Its what happens when the plant is absorbing too much liquid… Is that even possible in a hydroponic system? Yeah it is. Edema causes the cellular structure on the leaves to swell up as they absorb moere and more liquid, to the point that they will rupture, often killing that leaf. Often you will also see crusty spots on the leaves from dried sap and water.

In mild cases its not usually an issue, but more and more of our tomato branches were becoming effected. It tends to effect the lower branches or leaves first, slowly effecting more of the plant if the environment remains unchanged.

There are a couple reasons why it can happen:

  • There isn’t enough airflow around the plant and the plant isn’t transpiring enough (sort of like you getting hot and sweaty without a cool wind). This can also happen if the plant leaves is too dense and thick, restricting airflow around inner branches. This is the most common reason.
  • The nutrients are unbalanced; the plant is sucking up too much liquid to try and get enough of one or more nutrients.
  • The water is too warm whilst the leaves are cooler, causing the plant to activate drinking mode. Sort of like when a plant is growing in a hot region – when it rains the upper plant becomes cool and signals to the roots that fresh water is being supplied.

I will write a blog post covering edema bit more and ways to resolve this. It affects all plants, not just tomatoes.

In our situation, the foliage was becoming too dense. The constant but small airflow that we had in the room wasn’t reaching the inner branches and leaves, so the plant wasn’t able to lose the excess liquids through sweating.

Over Dense Foliage on San Marzano Tomato, Week 6 Growth in Kratky Hydroponics
Over Dense Foliage on San Marzano Tomato, Week 6 Growth in Kratky Hydroponics

For now our solution was to maintain a slightly more average temperature in the grow room rather than cooler at night and warmer during the day. We are still researching the ideal fan for our grow room as some people have had issues with the common oscillating fans causing leaf burn due to overexposure of wind.

Fruitful Endeavours

Flowers on San Marzano Tomatoes at 6 Weeks, Grown In Kratky Hydroponics
Flowers on San Marzano Tomatoes at 6 Weeks, Grown In Kratky Hydroponics

It’s not all bad news; our “hard work” is paying off. The tomato plant is only 6 weeks old, and yet we have been getting flowers now for nearly two weeks!

Flowers on San Marzano Tomatoes at 6 Weeks, Grown In Kratky Hydroponics
Flowers on San Marzano Tomatoes at 6 Weeks, Grown In Kratky Hydroponics

San Marzano are an indeterminate tomato plant variety, meaning they will continuous flower, fruit and grow indefinitely as long as the environment is ideal. So it makes sense that not all the flowers are opening at once. I did a count of the flower buds that I could see – both opened and unopened. There was over 35 flower buds!

Flowers on San Marzano Tomatoes at 6 Weeks, Grown In Kratky Hydroponics
Flowers on San Marzano Tomatoes at 6 Weeks, Grown In Kratky Hydroponics

The average San Marzano tomato weighs around 120-140grams (4.2-5oz). Assuming all 35 flowers produce tomatoes, thats a minimum of 4.2kg (9.2lbs) of tomatoes! I’m so glad that I have bought some canning equipment so I can bottle up these delicious tomatoes.

Have you preserved your home-grown or store bought tomatoes? Whats your favourite way to use tomatoes? Mine is definitely pizza sauce. Let me know in the comments below.

Growing San Marzano Tomatoes in Kratky Hydroponics – Update: Month 1

Its been a month now since I planted my San Marzano Tomato seeds, and I am still in awe! I honestly can’t wrap my head around how fast these tomatoes are growing. I expected like one or two leaves a week, not one or two leaves growing every single day! Maybe all tomatoes grow this fast… I’m a first time grower and I am honestly hooked.

First, lets see how they have grown over the last few weeks:

And now, be amazed:

San Marzano Tomato 1 Month, In Kratky Hydroponics
San Marzano Tomato 1 Month, In Kratky Hydroponics

They have doubled their size in one week! I said they were growing fast, right? One of the seedlings (one on the left in photo above) was a little slow in recovery after transplanting, so his growth is a little slower than his brother. Perhaps he experienced a bit more shock when transplanting.

San Marzano Tomato 1 Month, In Kratky Hydroponics
San Marzano Tomato 1 Month, In Kratky Hydroponics

I’m not going to even bother counting how many leaves the bigger of the two has now. Last week he had nine branches, and I as already impressed. He grows new branches so fast that I wouldn’t be surprised that by the time I finish counting there would be another emerging.

San Marzano Tomato 1 Month, In Kratky Hydroponics
San Marzano Tomato 1 Month, In Kratky Hydroponics

Once a brach seems to get old enough, new smaller leaves and branches start to emerge from those.

Here is a close up of some of the newer growth. I think this growth has emerged since last night.

San Marzano Tomato 1 Month, In Kratky Hydroponics
San Marzano Tomato 1 Month, In Kratky Hydroponics

The growth is just impressive. We’d be in trouble if tomatoes became sentient and tried to take over the world.

San Marzano Tomato 1 Month, In Kratky Hydroponics
San Marzano Tomato 1 Month, In Kratky Hydroponics

I can safely say that he has doubled his size in just one week! He is now 12 inches, or 30cm, tall. Last week he was only 5 inches, or 12cm, high! It seems that the more leaves he grows, the faster he grows. With 6 inches of growth in one week, I am super excited to see how much he grows in the coming week.

Have you grown tomatoes before? Do they honestly grow this fast, or is he growing faster in the hydroponics? Have you any tomato growing tips to share with a first-time grower?

Growing San Marzano Tomatoes in Kratky Hydroponics – Update: Week 3

I wouldn’t have believed it a month ago when you said I could grow tomatoes so easily in Kuwait’s hot desert weather; but here I am, just growing tomatoes. Of course I cheated a little by growing them inside the house, in a climate controlled area… and then I removed the soil and decided to grow them hydroponically.

And they are still growing!

My little plant babies are now three weeks old, and wow have they grown. This was them only one week ago:

Their stems had just started to turn brownish tinged close to the cloning collars. They both also had two new branches.

And this is them now, at three weeks old:

I just can’t believe how fast they are growing. I can turn my grow lights off at night, then when I re-enter in the morning they have grown an entire branch! No joking, I have seen an entire baby branch just pop up in the space of a few hours.

I have preemptively placed their first trellis support bars. Since we are using custom painted Ikea Ivar cabinets to hold our plants, we bought the bottle rack as a DIY trellis. This provides some basic support for the plants, and lets me tie them in place. We can also easily raise or lower the bottle rack as needed, and even add more as the tomatoes grow in height.

San Marzano Tomato Week 3, In Kratky Hydroponics
San Marzano Tomato Week 3, In Kratky Hydroponics

This is the weaker of the two tomatoes; he isn’t growing as fast. He now has four branches, two of which are fairly large. I noticed that once the dominate grower had put out one or two smaller branches, he had substantial increase in growth speed. I expect this one would probably grow much faster in the coming week.

The dominate grower is outpacing him pretty fast; he has a total of nine little branches all emerging. He’s also about 2″ (5cm) taller than his sibling. His centre branch is just touching the trellis bars, so hopefully in the next few days he will be resting against it and can be supported with the tie.

San Marzano Tomato Week 3, In Kratky Hydroponics
San Marzano Tomato Week 3, In Kratky Hydroponics

Both tomato plants seem to be developing some good root structures. I couldn’t lift the buckets out too high as the trellis bars are now in the way, but you can see the roots extend much further down into the bucket and nutrient water. The roots are nice and white, which is a sign of plant health when it comes to hydroponics.

San Marzano Tomato Week 3, In Kratky Hydroponics
San Marzano Tomato Week 3, In Kratky Hydroponics

Have you grown tomatoes hydroponically, or maybe traditionally in soil? Do you have any tips to share with a first-time grower?

Seed Germination Temperatures

A bit over a week ago I planted some spinach seeds, and sadly they didn’t germinate. I began a bit of research as to why. Despite my spinach varieties being hardy to warm weather, they still need cooler soil to germinate! The adult growth stage can handle warmer temperatures but the seedlings are too vulnerable still.

I began to wonder what I could grow with my current temperatures. It’ll also be handy to know the minimum temperatures for when the seasons change.

Whilst my plants aren’t being planted in soil, instead hydroponic is usually planted in rock wool or peat moss, the germination temperature should theoretically remain the same.

Optimal °FOptimal °C
Amaranth, Red Leaf68-7520-24
Basil, Purple Petra65–8518-30
Basil, Genovese70 – 9021 – 32
Broccoli45 -85 7-29
Cilantro55-7013-21
Cucumber, Lemon70–9021-32
Kale, Nero Toscana 65–8518-30
Lettuce, Little Gem (Romaine)40-755 – 24
Lettuce, New Red Fire60–7016-21
Lettuce, Red Sails60–7016-21
Lettuce, Red Salad Bowl50-7210-22
Pepper, Cayenne65-9518-35
Pepper, Jalapeño 65-9518-35
Spinach, Matador50–7510-24
Spinach, Lavewa50–7510-24
Spring Onion68-7720-25
Swiss Chard, Bright Lights75–9024-32
Swiss Chard, Lyon50 – 7510 – 24
Taisai, Pak Choy50- 8010 – 27
Tomato, Marmande VR60 – 7015 – 20
Tomato (Cherry), Supersweet 100 FT75 -9021-32
Tomato, Sam Marzano70–9021-32

I measured my Aerogarden water and it’s hitting a maximum of 85°F (30°C)! No wonder my spinach never sprouted, its ideal temperature is 50-75°F (10-24°C). Its just way too hot for them.

I’ll have to wait a while for the weather to get a bit cooler before I can sprout spinach; in the meantime I can try growing some Bright Lights Swiss Chard and Nero Toscana Kale.