6 Factors To Success When Selecting Hydroponic Plants

The Smart Hydroponics
- Last updated
- November 12, 2021
To have success when selecting hydroponic plants you need to consider factors that will have practical implications if overlooked; especially if you are just starting the hydroponic journey.
I have summarised the 6 factors to success to consider when selecting hydroponic plants below; most are practical factors which relate to the suitability of a plant to be grown in a hydroponic system, and of course economics as well:
- Weight. If your plants will become big and heavy (such as potatoes, carrots, tomatoes), you need to think about the supporting structure. It needs to be strong and suitable to support the weight and allow for the roots to develop. If you don’t have access to appropriate materials to build a strong enough structure, then you should consider lighter weight plants when selecting hydroponic plants: such as herbs, lettuce, kale, spinach, rocket, swiss chard, endive, bok choy, turnip greens.
- Space (lateral space and height). Some plants need lateral space and height; they are usually those which develop fruits rather than green leafy plants which usually grow smaller. So make sure you know how tall and wide your plants will become to allow for adequate space. If they grow tall, make sure your grow room is high enough and that you have a way to support the plant. For example, tomato plants with fruit on them will need structural support usually with strings attached to a mesh above the plants. This is a critical factor to success when selecting hydroponic plants.
- Root depth. Normally that would not be an issue, just make sure that you follow common sense when selecting hydroponic plants. Think that the roots grow nearly as much as the upper part of the plant. That will give you a rough guide of the space a root may need when you use a growing medium. If your hydroponic system is not using a growing medium, such as Aeroponics, NFT or Ebb & Flow ensure that roots are not too congested and some space is allowed for aeration and for the nutrient to effectively reach all parts of the roots.
- Time until harvest. Some plants will be faster in growth and you will be able to get your first harvest faster; these are usually the green leafy vegetables rather than the ones forming fruits. If you don’t want to wait for too long, then choose accordingly. Another way to speed up the time until harvest is to buy ready seedlings rather than starting from scratch by planting seeds.
- Controlled environment. Although hydroponics is closely related to controlled environments, you may have chosen not to introduce controls for air and water temperature or lights. So you need to know when is the best time of the year as a factor to success when selecting hydroponic plants. You will need to rely on your room temperature and the sunlight direction and hours. Some plants will need higher or lower temperature, or more or less light. If you want to read more about how to control environmental parameters, check out my Post on Best Time of the Year for Indoor Hydroponic Plants and 12 Hydroponic Problems and Solutions to Avoid Disaster.
- Economics, of course, unless you are doing it for fun which is equally exciting! So my view is that since you are getting into this and spend hard earned cash and time in educating yourself and setting your system up, it needs to be giving you back something apart from achievement satisfaction. Choose then a vegetable that you like and that is pricey to buy from the stores. Ok, if you are just starting the hydroponic journey you can go for something relatively inexpensive and easy to grow but moving on experiment with vegetables which would be a sizeable part of your grocery bill all year round.
The table below gives you condensed information for some typical hydroponic plants as a good first guidance.
| pH | EC (μS/cm2) | Temperature | ARTIFICIAL* light hours per day | Time until harvest from germination (or cutting/clone) to harvest | |
|---|---|---|---|---|---|
| Tomatoes | 5.5-6.5 | 2.0-5.0 | 58-79 F (14.5-26 C) It can go up to 90F (32F) | Up to 16 hours | 2-3 months |
| Potatoes | 5.8-6.2 | 1.0 until the 4th week and then 4.0 | 65-75 F (18-24 C) | 10-12 hours | 70-80 days (from cutting) |
| Carrots | Around 6.3 | 1.6-2.0 (for ke factor of 700) | 65-75 F (18-24 C) | 12-16 hours | 2-3 months |
| Beans | 6.0-6.5 | 2.0-4.0 | 70-80 F (21-26.5 C) at day cycle 65-70 F (18-21 C) at night cycle | At least 12-13 hours | Harvest before maturity when beans are tender (maturity at 60-90 days) |
| Strawberries | 5.5-6.5 | 0.8-1.4 | 65-75 F (18-24 C) | 14-18 hours | 7-10 weeks (from clone) |
| Bok Choy | 5.5-6.5 | 1.5-2.5 | 55-75 F (13-24 C) | 14-18 hours | 7-9 weeks |
| Kale | 5.5-6.5 | 1.6-2.5 | 45-85 F (7-29.4 C) | 14-18 hours | 6-8 weeks |
| Lettuce | 5.5-6.5 | 1.0-1.6 | 45-75 F (7-24 C) | 14-18 hours | 6-8 weeks |
| Swiss Chard | 5.5-6.5 | 1.6-2.3 | 55-75 F (13-24 C) | 14-18 hours | 6-8 weeks |
* ARTIFICIAL light hours are roughly double of the direct sunlight hours. For example, tomatoes will need up to 16 hours of artificial light while they would need up to 9 hours max direct sunlight.
Some sources if you fancy further reading:
- The Beginner’s Guide to Hydroponic Tomatoes
- 11 Must-Know Tips To Growing Tomatoes Indoors
- Growing Potatoes Hydroponically – a Full Guide
- Growing Hydroponic Carrots – a Full Guide
- TDS, EC and PPM Explained
- Growing Beans Hydroponically; Planting; Care; Harvest
- pH/ TDS / PPM / EC of Water for Hydroponic Plants
- Best Crops For Hydroponics Guide
