Plants can’t survive from water alone; they need nutrients as well. In traditional growing, the plants will often get what they need from the soil (and even then you often still add fertilisers). But hydroponics removes the soil. Instead you need to use hydroponic solutions with the correct ratios of nutrients; too much or too little and your plants will suffer and potentially die!
I use General Hydroponics Combo Ferilizer pack for my hydroponics. In fact a lot of people recommend this brand. This brand has split the different nutrients a plant needs into different bottles. Plants need different amounts of various nutrients depending upon their growth stages; and the General Hydroponics Combo pack comes in three bottles that each contain different concentrations, allowing you to target each growth stage and get maximum growth and yields!
Mix the following amounts of nutrients into one gallon, or 3790ml, of water. I recommend filtered water to help reduce debris and other microbes from entering your hydroponic systems.
All nutrient measurements are taken in teaspoons.
Seeds & Cuttings
Late Vegetative to Pre-Bloom
Bloom to Fruiting
I use the vegetative ratios of 3-2-1 for my Kratky lettuce since its main goal is to grow vegetation and leaves. Ideally I don’t want my lettuce to bolt and flower as the leaves will turn bitter.
Want to try out hydroponics, but don’t want to spend much? Honestly it’s a big field with lots of complex terms and companies selling you the “next must have” item…. Let me help you create your first hydroponic setup without spending much, or maybe even without spending a single dollar!
Our goal is to create a “set and forget” system to grow lettuce.
Most people will do their first hydroponics with mason jars. They are such a versatile jar that pretty much every house has one, and they are cheap!
I personally recommend the largest jar possible; it’s more “set and forget”. Lettuce roots don’t need too much space to grow, but depending upon your environment and its growth rate you may find yourself adding water to a small jar every so often.
Hydroponic containers have to be opaque and black to stop algae growth… but you won’t find any mason jar like that. Instead, wrap the jar well with aluminium foil, or even paint a couple layers of black gesso or acrylic paint on the outside! If use chalk paint and you can later write or decorate your jars with chalk pens.
The Yoghurt Cup or Net Cup
If you have plenty of plants around your home, you may have a net cup already. They are often those little plastic cups with slots or holes in them that come with smaller plants. Make sure it fits. I use these 2″ wide-rim cups from CZ Garden.
Alternatively, you can recycle a plastic yoghurt cup. To be safe, please check What Plastic Should I use for Hydroponics? as not all plastics are safe to reuse. In the picture below you can see how I reused a sour cream cup:
Plants will often get all their nutrients from the soil you plant them in, although sometimes you will add fertilizers or compost. Hydroponics removes the soil from the growing process, so you need to come up with an alternative way to feed the plants nutrients.
Next you need to decide what plant you are going to grow: lettuce and basil are some of the most common plants for people to try for their first grow since they are fast growing, cheap and easy to manage. With the right setup you can even grow big plants like tomatoes (but they won’t grow in mason jars, sorry)!
GettyStewart has a great post about How to Regrow Romaine Lettuce from the Stem. She does point out that regrowing from a stem won’t produce leaves as large as store bought plants; and this probably has to do with the amounts of nutrients and lights that a store-bought plant receives compared to a stem in plain water.
I prefer to grow from seed; it has a fairly high success rate and only takes two to three weeks before I am harvesting. You can buy packs of various seeds fairly cheap, or individual packs from stores such as Botanical Interests.
Hydroponics is mostly about removing the soil from growing plants, but you can’t just plop them into the water and hope for them to survive (some plants do, but most wont)!
You will need some form of grow medium. There are several different options with the easiest and most common being peat moss, rock wool and clay pebbles.
I regularly use Jiffy 7 Peat Pellets. They come in various sizes. Since the peat pellet is too small to fill up my entire DIY net cup, I pack clay pebbles around it. Alternatively you can use rock wool. You can simply cut up extra rock wool cubes to fill any spaces in your net cup. If you don’t want to cut up the extra rock wool, you can of course use clay pebbles as well.
It’s important to fill up the entire cup; we want to make sure that no light will get beyond the grow medium and into the mason jar.
Most people will put their mason jar and plant in the window, and generally there will be sufficient light for plant growth. Unfortunately my kitchen window is underneath a building overhang and thus gets very little light; so I need a grow light.
If you opted to paint your mason jars black, now is the time. Paint only the outside of the jar, remember that the paint itself is unlikely to be food-safe. Paint right up to the rim of the jar. Paint two to the three layers so that no light can leak inside.
Cut Your DIY Grow Cup
If you are using a recycled yoghurt cup, its time to cut some slits and holes in the bottom of the cup. Slits are generally better as they hold the grow medium without spilling, but still provide enough space for roots to grow through.
Any non-living supply should be sterilised; jars, containers, and grow medium. The easiest way to do this is to submerge everything in hot water.
Fill your mason jar until the water level passes the bottom of the grow cup or yoghurt container by approximately .25″ or 1cm.
If you have excess water left over, you can water other plants with the mixture or store it to top up your lettuce water. You should not pour it down a drain! I store my excess nutrient mixes as I live in a dry climate and find water tends to evaporate faster than the plants are able to absorb.
Plant Your Seed
Make a small hole, usually about .25″ or 1cm deep, in your grow medium. Drop two to three seeds in and fluff grow material on top to cover lightly. Not all seeds with germinate, so it’s generally a good idea to put at least two seeds. If multiple sprout, you can always transplant or pull out the extra growth.
Place your grow medium in the centre of the cup, ensuring that the bottom of the grow medium is in contact with the water. Surround your grow medium with clay pebbles, or more rock wool.
Set and Forget
Place your mason jar somewhere bright, like a window.
And thats it! Over the next few days your plant should sprout. Some plants do take longer to sprout, so check your seed packet. My basil usually sprouts in about 5 days; at least you can see the tiniest of plants emerging around then.
If your plant didn’t sprout:
You may need to wait longer; check on the seed packet for how long it takes for that variety of plant to sprout. Some species can take 20 or more days!
Make sure your grow medium is moist the entire time the seeds are sprouting; if you live in a very dry environment your water level may evaporate too fast for the seedlings to produce roots.
You could also have some bad seeds, try refilling your jar and planting more or new seeds.
If you notice your plants becoming wilted, chances are the water level is evaporating faster than they can absorb. Fill up your jar a little at the time! It’s very important to not fill the jar up the entire way; as the water level decreases the plant will grow water-roots and air-roots. If you submerge your air-roots in water your plant will literally drown. If you want to maintain your water level, I suggest the half-way point of the jar.
If your plant seems to be growing long leaves that aren’t very wide, you may not have enough light. Check out my post Do I Need Grow Lights? where I teach you how to measure the amount of light in your room.
I’ve seen some Youtube videos and articles where they grow their hydroponic plants in pool noodles. They claim to get high harvest yields, and they regularly talk about the benefit of being able to reuse the pool noodles.
I was concerned about the safety of using pool noodles; as we know plastic can leach chemicals and micro-particles into the water and plants (and eventually you). This process is often sped up with exposure to high temperatures… and Kuwait set a world record for the highest temperature in the world reaching 52.2°c (126°f) in the shadows and 63°c (126°f) in the direct sun!
After I bought the collars I realised that there weren’t many people online saying you could start seeds in the collars; they are generally used for transplanting cuttings from older plants.
I decided to do an experiment on whether I could grow seedlings in cloning collars.
I’m starting this experiment on Aug 7, 2019.
I sterilised the cloning collar and the container with hot water.
If you look closely you can see the Lemon Cucumber seed in the middle of the cloning collar. I’ve inserted it so its very close to the bottom of the collar (I’m holding it upside down), but far enough in that it hopefully doesn’t fall out.
Apparently seedlings will grow best when exposed to high levels of humidity. I wanted to make sure that my seedling could get as much light as possible at the same time. So I found this old Ikea air-tight plastic container. It has a de-gas spout which I have kept closed.
Fingers crossed that this container won’t grow algae since my nutrient rich water is also exposed to light.