What Vegetables Can You Grow Hydroponically?

Growing vegetables indoors for beginners

​​With indoor living space ​usually at a premium,  no one really wants to grow plants indoors without a good reason. Those reasons might be aesthetic: growing nice-looking plants or flowers, or they may be functional: growing plants that improve the air quality within the home. However, these days more and more often​ the main reason for wanting to grow plants indoors is to join the growing ranks of the 'grow your own food' movement.

​Growing indoors however is not as easy as it may at first ​appear. ​A bit of planning is required and a number of questions need to be answered ​before embarking on the growing process. ​Two of the most important questions to answer before starting any indoor garden are: What growing technologies should ​we use ​and what vegetables will grow successfully?

There are several ways to go about growing plants indoors with several technological options available ​including various forms of hydroponics, aquaponics, and aeroponics. One of the best ​ways to grow vegetables indoors as a beginner is ​to use hydroponics, and more specifically, a version of hydroponics loosely ​known as 'Kratky hydroponics'. The Kratky hydroponics technique is becoming increasingly popular as it is simple and low in cost, but not all vegetable plants can be grown in this system successfully. Further down the page you will find some of ​our grow diary experiments of growing various vegetable plants indoors using the Kratky hydroponics system, but first let's take a look at what it takes to setup and start your own indoor vegetable garden as a beginner.

​There are a number of points to take into consideration before starting to grow vegetables indoors. ​These include:

  • Where should you set up your ​indoor garden​? Remember that the plants are going to take literally months to grow (depending on the vegetables) and you won't be wanting to move them around all the time. The location needs plenty of light (natural or artificial), reasonable temperatures and not get in anyone's way. A grow tent and LED lighting may be necessary if space is in short supply within the home.
  • ​What sort of growing system should you use? Soil-based? ​Hydroponics - recirculating or not​? Aquaponics? Or should you use something else more experimental, like ​a​eroponics? Each comes with its own pros and cons and each has its own specific requirements. Kratky hydroponics is a good place to start for beginner indoor gardeners.
  • ​What other accessory equipment will you need? ​​This might include germinators and seed starter media, and in the case of hydroponics, one will likely need a pH meter and a EC / TDS meter.
  • ​What sort of vegetables should you grow? You will want to pick vegetable plants that can be grown inside. Fortunately, most vegetable plants can be grown inside if you give them the right conditions.

​Once you have made the decisions of location, growing ​equipment, and the type of vegetables to grow, it is then time to gather the equipment together and start your seedlings.

​Easiest vegetables to grow hydroponically

​As a general rule of thumb, if a vegetable can be grown using traditional soil-based methods, then it can almost ​certainly be grown hydroponically. However, each type of vegetable plant has its own needs and requirements for it to produce a healthy and ample crop, and it is usually a matter of just adjusting the hydroponic conditions to suit the needs of the vegetable plant in question to get the maximum yield.

​We have personally experimented with growing a number of different vegetable plants in our conservatory using the Kratky system of hydroponics. ​These include herbs,  salad greens and some fruiting plants, all of which grew admirably. However, we have also experimented with plants which usually produce larger vegetables even though the Kratky system ​is not the ideal system to use, but providing valuable information on how well they grow using hydroponics. ​In general, flowering and fruiting vegetable plants need recirculating-hydroponic or similar systems, mainly because of their relatively large water / media volume requirements. Unfortunately, the non-recirculating Kratky system with its fixed nutrient media volumes prevents many of the fruiting vegetable plants from running their life cycle to completion as the nutrient media tends to run out ​before they ​can reach their full fruiting stage. However, as you will see from the grow diaries below, many of the vegetable plants grew very well ​in a hydroponics system, and ​they give a good indication of how ​well they will grow in ​a more appropriate​ hydroponic system where the media volume can be continuously ​topped up and/or adjusted until the vegetables are ready to be ​harvested.

​Herbs & Salad Greens

​So far the easiest 'vegetables' to grow hydroponically have been the herbs and salad greens - strictly speaking they are not​ the first plants that come to mind when talking about vegetables, but they do fall into the same food category. The main reasons for ​their ease of growth and ease with which you can get positive results with them are:  

  • check
    ​They are quick to give tangible (and ​ edible!) results since ​you only has to wait for the leaves to grow before they can be picked
  • check
    There is no ​need for the ​complicated processes of flowering, pollination and fruiting before ​you get edible products ready for the kitchen.
  • check
    ​There is ​relatively ​little wastage since you are eating most of the plant itself instead of eating ​just the fruit

Rocket

  • check
    Test Plants: ​Rocket (Arugula)
  • check
    Growth Medium: Aqua Vega - 730ppm - pH 6.2
  • check
    Location: ​Conservatory
  • check
    ​Hydroponics Setup: 10L ​Kratky hydroponics system

The Rocket plants grew very well in the 10L bucket Kratky hydroponics system and produced an abundant yield of leaves for several salads over the course of 3 months (note that the picture shows the plants AFTER ​having harvested leaves from ​them on several occasions).

The test grow was stopped when the plants began to bolt and produce flowers. Bolting may have been due to several reasons including plant age, longer days, or even natural changes to the nutrient media.

​Although the rocket grew well, the 10L bucket system was not ideal for rocket, which ​is likely to be more efficiently grown in flatter, lower depth containers, where a greater surface area on top permits the growth of more plants per container.


​Kale

  • check
    Test Plants: ​ Kale
  • check
    Growth Medium: Aqua Vega - ​870ppm - pH ​6.5
  • check
    Location: ​Conservatory
  • check
    ​Hydroponics Setup: ​10L Kratky hydroponics system

​Kale plants grew very successfully in the 10L Kratky hydroponics system. However, after about 2 months, the media was almost devoid of nutrients and the plants began to slow in growth and look decidedly less healthy. Had the nutrient volume or the concentration been ​higher, the plants probably could have continued growing for longer.

NB: leaves were continually harvested from the plants for tasting throughout the 2 months of growth so the picture to the right is actually an under-representation of total growth.


​Spinach 'Perpetual'

  • check
    Test Plants: ​Spinach 'Perpetual'
  • check
    Growth Medium: Aqua Vega - ​750ppm - pH 6.14
  • check
    Location: ​Conservatory
  • check
    ​Hydroponics Setup: 10L ​Kratky hydroponics system

​Spinach 'Perpetual' grew very successfully in the 10L Kratky hydroponics system. However, as with the Kale discussed above, the plants ​sucked up the nutrients from the media at a much higher rate than other plants tested in this hydroponics system (this may explain why Kale and Spinach are regarded as 'super-foods' ​and why they are packed with nutrients!?). As a result, the test grow ended only after about 2 months as the nutrient media became exhausted. 

Once again, note that the picture to the right does not represent total growth of the plant as leaves were continually picked from the plant for tasting throughout its growth.



Hot Peppers

After herbs, we have found the next easiest hydroponic vegetables to grow are 'hot' peppers. This is probably due to the fact that pepper plants are relatively hardy, the fruit are relatively small when they are ready to be harvested, and the flowers and fruit are plentiful in a fully-grown plant.

Jalapeno

  • check
    Test Plants: ​Jalapeno Hot ​Peppers
  • check
    Growth Medium: Aqua Vega ​- 1:250 - pH 6.5 
  • check
    Location: ​Conservatory
  • check
    ​Hydroponics Setup: ​10L Kratky hydroponics system

​Jalapeno Hot Pepper plants grew well in the 10L bucket Kratky hydroponics system using Aqua Vega nutrients, however, 10L is too small a volume for the Jalapeno plant to produce a good yield of hot peppers. In fact, in this test grow the plants were kept alive and producing hot peppers beyond the point where the nutrient media ran out, by adding small amounts of new media on a daily basis - not something you would want to do for any sizeable growing setup.

Even with these sub-optimal conditions, the Jalapeno plants produced a good yield of hot peppers from this Kratky hydroponics system.



Numex Sandia

  • check
    Test Plants: Numex ​Sandia Hot Peppers
  • check
    Growth Medium: Aqua Vega - ​1:250 - pH 6.5
  • check
    Location: ​Conservatory
  • check
    ​Hydroponics Setup: ​10L Kratky hydroponics system

​Like the Jalapeno Hot Peppers discussed above, the Numex Sandia Hot Pepper plants also grew strongly in the 10L bucket Kratky hydroponics system. However, once again, the 10L volume proved too small to get the plant to the end of its life cycle and produce a good yield of hot peppers. As with the Jalapeno plants, the media ran out after about 2.5 months of growth just as the fruit ​were beginning to develop, and the plants had to be sustained by daily additions of small amounts of new nutrient media. This hack kept the plants alive and producing a good yield of hot peppers for several weeks, so the grow was successful but a larger volume Kratky hydroponics system should be used with any future grow.



​Sweet Bell Peppers

Purple Beauty

  • check
    Test Plants: ​Sweet Bell Pepper (Purple Beauty)
  • check
    Growth Medium: Aqua Vega - ​1:400 - pH ​6.5
  • check
    Location: ​Conservatory
  • check
    ​Hydroponics Setup: ​10L Kratky hydroponics system

​A Purple Beauty Bell Pepper plant grew OK in the 10L bucket Kratky hydroponics system. However, as with the hot pepper plants, the 10L volume was insufficient for a fruit-bearing plant. Once again, just as fruit were developing, the nutrient media in the 10L bucket ​became exhausted and the pepper plant had to be sustained with occasional additions of small volumes of fresh nutrient media. 

NB: Only one plant out of two germinated, and the plant's growth did not appear to be as healthy as the other pepper plant species. This could be due to the plant variety itself, a genetically-deficient seed, or sub-optimal growth conditions.  However, the plant did reach maturity and was able to bear a few small bell peppers in this hydroponics system.



Broccoli

Calabrese

  • check
    Test Plants: ​Broccoli (Calabrese)
  • check
    Growth Medium: Aqua Vega - 750ppm - pH 6.​22
  • check
    Location: ​Conservatory
  • check
    ​Hydroponics Setup: ​10L Kratky hydroponics system

​An attempt at growing Broccoli (Calabrese) in the 10L bucket Kratky hydroponics system proved to be quite difficult. First of all, the plants grew quite elongated rather than remaining short and stout as one normally sees with traditional growing. However, this unusual growth may have been due to sub-optimal lighting conditions within the conservatory rather than any inadequacy with the hydroponics system. ​The second major problem with the Broccoli grow was that​ after only a couple of months, the nutrient media was finished and the plants had yet to develop any sign of the edible flower structures that we ​are so familiar with. Consequently, the grow ​was terminated early without getting to sample any edible produce.



​Courgette

​Verde di Milano

  • check
    Test Plants: ​Courgette (Verde di Milano)
  • check
    Growth Medium: Aqua Vega - 700ppm - pH ​6
  • check
    Location: ​Conservatory
  • check
    ​Hydroponics Setup: ​10L Kratky hydroponics system

​Courgette (Verde di Milano) plants grew strongly in the Kratky hydroponics system, however, as with other fruit-bearing plants, the 10L system used was woefully insufficient for these plants to reach the fruit-producing stage. As a consequence, after only 6 weeks, the nutrient media finished and the test grow had to be ended early just as the plants were beginning to produce flowers. 



​Eggplant

​F1 Baby Belle

  • check
    Test Plants: ​Eggplant (F1 Baby Belle)
  • check
    Growth Medium: Aqua Vega - ​​1:300 - pH 6.​​5
  • check
    Location: ​Conservatory
  • check
    ​Hydroponics Setup: ​10L Kratky hydroponics system

​Only one of the two Eggplant (F1 Baby Belle) ​seeds germinated in this test grow, however, the plant grew strongly in the Kratky hydroponics system. Once again, like other fruit-bearing plants, the 10L volume of the system was inadequate to get the plant to the fruit-​producing stage, with the nutrient media running dry around 2 months into the grow. Future grows should use a recirculating hydroponics system to get round the problem of the plants requiring large volumes of water and nutrients.