I can’t believe the time has past so fast. The peppers are growing faster!
Don’t feel like reading? Well I’ve recorded a video of this weeks update:
This week I was able to top all the peppers. By cutting the very top of the branch, a technique known as topping, you encourage the pepper to back-bud and for the stem to thicken. In most times those back-buds will turn into new branches.
Here you can see some back budding on the Numex Twilight variety, that I topped several days ago. The new buds are still quite small and look almost like the first leaves the seedling grew.
Last week I was able to top the fastest growing plant, the Marbles variety. It’s easy to see how fast the peppers are growing; its got plenty of new leaves. Looking underneath the leaves you can see how new branches are forming and growing from the main stem.
Marbles Variety Pepper, 1 Week After Topping
Many of the varieties are starting to show their individual characteristics now. Some varieties have darker colored leaves than others, for example. Some leaves are also more rounded, whilst others are longer and more triangle shaped. This is most evident when viewed side by side:
Marbles and Starlight Pepper Leaf Comparison
Some of the peppers are much slower growing than others. The Bolivian Rainbow variety with its purple leaves is easily half the size of his siblings, if not smaller. You can see him in both the photo above and below:
I topped him about two days ago, and you can see very small back budding starting to form (the lighter green leaves).
Birds Eye Baby and Bonzi Seedlings That Just Germinated
Finally, I started some new seedlings of the varieties that didn’t seem to germinate last month. So far Birds Eye Baby, Bonzi and Chinese 5 Color pepper varieties have germinated. That makes 13 total varieties of peppers growing, including the larger jalapeños.
So far in my experience plants will germinate in a flourish – a little rush to get one or two leaves out – and then they will stagnate for a week or so. Its during this time of stagnation that they usually focus on root growth. Last week our strawberries had barely broken the rock wool surface, featuring only their dicot leaves.
Growing Strawberry Temptation in Kratky Hydroponics, Week 2 Growth
This week is different, in the sense that something only 1.5cm (just over 0.5″) could be different:
Growing Strawberry Temptation in Kratky Hydroponics, Week 3 Growth
Growing Strawberry Temptation in Kratky Hydroponics, Week 3 Growth
It was quite hard to get my camera to focus clearly on such small details, but you can still see that the Tempation Strawberries are now going through a growth spurt. On all of the seedlings they are beginning to grow their second set of leaves.
It’s going to be quite a while before my plants will bare fruit, but I am still very happy with their progress; previously I had several months of attempts to germinating the plant with little success. The only method that worked in the end was stratify the seeds in the fridge for over a month. To get this far is quite an achievement!
I have a lot of greenery growing, but not enough fruit… yet. Two weeks ago I planted some Strawberry seeds; the Temptation variety. I mean… I’m very tempted to eat strawberries… (bad joke, I know).
Growing Strawberry Temptation in Kratky Hydroponics, Week 2 Growth
Growing Strawberry Temptation in Kratky Hydroponics, Week 2 Growth
They don’t look like much, but these seeds are currently a 7 week effort to get growing!
A while back I learnt that some seeds won’t germinate at warmer temperatures, and in fact need to experience freezing temperatures in order to leave dormancy. You can mimic these temperatures by storing your seeds in the fridge. This process is called stratifying. So for the last month I have had a variety of strawberry seeds just chilling away in the fridge, literally.
To see the seeds actually germinating is really quite rewarding. I was beginning to think that I wouldn’t be able to grow any. I’m very much looking forward to seeing how these grow over the coming weeks.
In the post Do I Need Grow Lights I measured the amount of light in each of my grow rooms, hoping to figure out which room would produce the best plant growth. At the time I was hoping to not have to invest in a grow light; man was I wrong!
A Short Warning
LUX, or lumens, to determine plant growth is widely inaccurate due to the different types of lights and the wavelengths light types each produce. Plants need certain wavelengths, or colors, to grow. No matter how bright your lights are if they are missing those wavelengths then then the plants will just not grow.
This post will not consider the wavelength or colors of lights. I’m trying to keep it as simple as possible so that anyone can follow along, even without fancy gadgets like quantum meters which can easily cost US$500. Future posts will explain wavelengths in detail. Beginners Guide To Hydroponic Lighting has a list of all the posts on how to measure and set up your lights.
You need the umol’s value or the umol/s/m2: in essence umols are how bright your light is. This value is also known as “photosynthetic photon flux” or PPF. Note that PPFD is a different value, taking into account the distance from the light.
Too low of a light strength on your plants may lead them to not growing, and too high may burn or kill them.
How To Calculate Bright Your Light Is
Most people don’t have fancy tools to measure the amount of light in their homes, such as a PAR meter or a quantum meter. Thankfully, you can get free apps on your phone that measure lumens easily.
You can use the Plantekno website to convert LUX to umol/s/m2. Note: many grow lights will tell you the PPF or umol/s/m2.
Natural sunlight has a PAR value of 900-2000μMol/m2/s when directly overhead, varying with location and season. For a grow light to be effective, it will have PAR values of 500-1500 μMol/m2/s.
In comparison, I measured my kitchen window light at 250LUX or 4.6umol/s/m2. No wonder my plants kept dying! As you’ll see below, its way below the minimum light requirements for lettuce to grow.
But how bright should my light be?
Be aware that not all aspects of how much light plants need are fully researched yet : Lefsrud at McGill University has extended upon NASA research and one thing he noted was common incorrect assumptions. For example, many people consider lettuce to a shade loving plant and tomatoes to enjoy full sun. However when shone with 5000 umol’s, the tomatoes suffered whilst the lettuce showed no signs at all! The exact opposite of what was expected.
Research Gate website had several listed studies that mentioned the number of umol’s used for ideal plant growth:
Minimum umol’s Required
Lettuce
100-200
Watermelon
250
Tomatoes
400-500
According to the company Valoya the amount of umol’s a plant needs will vary depending upon its growth stage: seedling, vegetative, flowering/fruiting. They claim that lettuce needs approximately 80 umols during seedling, 150 for vegetative stage and 200 when it begins to flower.
Valoya’s Comparison of umol’s for Lettuce Growth
I found a really great article from the Department of Horticulture and Crop Science: this PDF covers a huge variety of plants, and the recommended lighting and hours lit for each of the growth stages, and what level nutrient solution is ideal.
Here is a small sampling of some common plants and their needed light intensity (taken from above PDF link):
Lettuce
# Light Hours
Light Intensity (umols)
Propagation
12-20
150-250
Vegative
12-20
250-450
Flowering
12-20
250-450
Strawberries
# Light Hours
Light Intensity (umols)
Propagation
12-20
250-450
Vegative
12-20
250-450
Flowering
<12
250-450
Fruiting
12-20
250-450
Tomatoes
# Light Hours
Light Intensity (umols)
Propagation
12-20
250-450
Vegative
12-20
450-700
Flowering
12-20
450-700
Fruiting
12-20
450-700
Where To From Here?
Notice how I mentioned the number of light hours needed for plants in the tables above? Different plants need different lengths of light exposure. You can’t just leave your grow light on 24/7! The next post in this series is How Long Should My Hydroponic Lights Be On? It explores Daily Light Integral or DLI, the measurement that takes into account growth light strength x time its on for optimal growth.
Beginners Guide To Hydroponic Lighting has a list of all our posts on lighting, written to help a beginner learn the basics and get started right through to more advanced topics.
Do I Need Grow Lights? is the previous step in this series. Not everyone has a PAR meter or Quantum meter; they can be expensive. So how else can you measure the light your room gets? Whilst not very accurate, this can give you an idea of how bright your rooms are; helpful in finding out if you need to invest in a grow lamp!
How Long Should My Grow Lights Be On For Hydroponics? is the next step in this series. You know how bright your light should be, but how long should it shine? Plants need time to sleep and rest too, just like you. This post explores how to determine how many hours of light your plant needs (it can vary a little depending upon how bright your light is).
