pH/ TDS / PPM / EC of Water for Hydroponic Plants
We often get asked what the nutrient requirements are for specific plants, and this is the informative article we refer to.
The pH and electro-conductivity values specified here are just vague guidelines. Your specific plant growing requirements will vary according to regional climatic conditions, and from season to season within that region.
EC reading should be monitored. These values for hydroponic plants only (soil-grown plants will differ slightly).
The concentration of salts ms cm is what we measure with an EC or ppm meter.
Nutrients generally dissolve in water and provide resistance measured by EC & PPM Meters.
Positively charged ions conduct electricity measured in ppm
Temperature affects the pH of water however most good pH meters have automatic temperature compensation.
Some cheap pH meters come with a sachet that you dissolve in distilled water
Consider buying a pH Meter & EC Meter to feed your plants nutrient accurately.
Electro-Conductivity (EC) or Conductivity Factor (cF) can be expressed as either milliSiemens (mS), cF, or parts per million (PPM) 1 mS = 10cF = 700ppm.
Joining a hydroponic community forum relating to the plant you are growing to unlock your full potential with maximum yields.
Check out:
Simple Guide to Understanding Nutrient Concentration or How to Test Soil pH
| Plants | pH | cF | EC | PPM |
| Ambra radicchio | 5.5-6.5 | |||
| Artichoke | 6.5-7.5 | 8-18 | 0.8-1.8 | 560-1260 |
| Asparagus | 6.0-6.8 | 14-18 | 1.4-1.8 | 980-1260 |
| Bean (Common) | 6.0 | 20-40 | 2-4 | 1400-2800 |
| Beans (Italian bush) | 6.0-6.5 | |||
| Beans (Lima) | 6.0-6.5 | |||
| Beans (Pole) | 6.0-6.5 | |||
| Beetroot | 6.0-6.5 | 8-50 | 0.8-5 | 1260-3500 |
| Broad Bean | 6.0-6.5 | 18-22 | 1.8-2.2 | 1260-1540 |
| Broccoli | 6.0-6.5 | 28-35 | 2.8-3.5 | 1960-2450 |
| Brussell Sprout | 6.5-7.5 | 25-30 | 2.5-3.0 | 1750-2100 |
| Cabbage | 6.5-7.0 | 25-30 | 2.5-3.0 | 1750-2100 |
| Capsicum | 6.0-6.5 | 18-22 | 1.8-2.2 | 1260-1540 |
| Carrots | 6.3 | 16-20 | 1.6-2.0 | 1120-1400 |
| Cauliflower | 6.0-7.0 | 5-20 | 0.5-2.0 | 1050-1400 |
| Celery | 6.5 | 18-24 | 1.8- 2.4 | 1260-1680 |
| Collard greens | 6.5-7.5 | |||
| Cucumber | 5.8-6.0 | 17-25 | 1.7-2.5 | 1190-1750 |
| Eggplant | 5.5-6.5 | 25-35 | 2.5-3.5 | 1750-2450 |
| Endive | 5.5 | 20-24 | 2.0-2.4 | 1400-1680 |
| Fodder | 6.0 | 18-20 | 1.8-2.0 | 1260-1400 |
| Garlic | 6.0 | 14-18 | 1.4-1.8 | 980-1260 |
| Leek | 6.5-7.0 | 14-18 | 1.4-1.8 | 980-1260 |
| Lettuce | 5.5-6.5 | 8-12 | 0.8-1.2 | 560-840 |
| Marrow | 6.0 | 18-24 | 1.8-2.4 | 1260-1680 |
| Okra | 6.5 | 20-24 | 2.0-2.4 | 1400-1680 |
| Onions | 6.0-6.7 | 14-18 | 1.4-1.8 | 980-1260 |
| Pak Choi | 7.0 | 15-20 | 1.5-2.0 | 1050-1400 |
| Parsnip | 6.0 | 14-18 | 1.4-1.8 | 980-1260 |
| Pea | 6.0-7.0 | 8-18 | 0.8-1.8 | 980-1260 |
| Peas (Sugar) | 6.0-6.8 | |||
| Pepino | 6.0-6.5 | 20-50 | 2.0-5.0 | 1400-3500 |
| Peppers | 5.8-6.3 | 20-30 | 2.0-3.0 | 1400-2100 |
| Bell peppers | 6.0-6.5 | 20-25 | 2.0-2.5 | 1400-1750 |
| Hot Peppers | 6.0-6.5 | 30-35 | 3.0-3.5 | 2100-2450 |
| Potato | 5.0-6.0 | 20-25 | 2.0-2.5 | 1400-1750 |
| Pumpkin | 5.5-7.5 | 18-24 | 1.8-2.4 | 1260-1680 |
| Radish | 6.0-7.0 | 16-22 | 1.6-2.2 | 840-1540 |
| Spinach | 5.5-6.6 | 18-23 | 1.8-2.3 | 1260-1610 |
| Silverbeet | 6.0-7.0 | 18-23 | 1.8-2.3 | 1260-1610 |
| Sweet Corn | 6.0 | 16-24 | 1.6-2.4 | 840-1680 |
| Sweet Potato | 5.5-6.0 | 20-25 | 2.0-2.5 | 1400-1750 |
| Swiss chard | 6.0 6.5 | |||
| Squash (Summer) | 5.0-6.5 | |||
| Squash (Winter) | 5.0-6.5 | |||
| Taro | 5.0-5.5 | 25-30 | 2.5-3.0 | 1750-2100 |
| Tomato | 5.5-6.5 | 20-50 | 2.0-5.0 | 1400-3500 |
| Turnip | 6.0-6.5 | 18-24 | 1.8-2.4 | 1260-1680 |
| Zucchini | 6.0 | 18-24 | 1.8-2.4 | 1260-1680 |
Cannabis is grown Indoors at:
Max 1.4 EC / 700 ppm * during Vegetative phase
Max 1.6EC / 800 ppm * during Flowering phase.
a pH of 5.5 - 5.8
* without co2 injection and control.
As a general rule, plants will have a higher nutrient requirement during colder months, and lower demand in the hottest months. Therefore, a stronger nutrient solution should be maintained during winter, with a weaker solution during summer when plants take up more water than nutrients.
Some of the information on this page is sourced from: www.homehydrosystems.com/ph_tds_ppm/ph_vegetables_page.html
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