Indoor Gardening And Hydroponics FAQ's

Indoor Hydroponic FAQs

What temperature should I aim for?

Day time 25 – 28C, Night 20 – 23C

What humidity should be maintained?

50 – 60% is ideal in the grow tent

How long should the grow lights stay for day time?

  • Vegetative Growth / Phase = 18 hrs a day  (1-5 Weeks)
  • Flowering Phase = 12 hrs a day  (8 – 10 weeks) 11 hrs a day if it is really hot
There are different timings you can try, however these timings are tried and proven.

What distance between the light and plant is best?

Generally the gap should be 30cm for 315W, 35cm for 400W, 40-50cm for 600W and 60cm for 1000W grow lights. A fan blowing between the plant and the grow lights will help with the heat building up.  If using cool tubes lights can be closer.

What is the best light to use, High Pressure Sodium (HPS) or Metal Halide (MH)?

HPS outperforms MH when used for a whole grow and flower cycle. HPS noticeably outperforms MH if it is used for the flower stage, but MH performs much better during the growth phase. For best results, MH for grow and HPS for flowering.

How often should I change my grow lights?

For best results change your grow lights every 3000 hours (every 2 cycles using a single grow light). There is a 10% loss between 3000 - 4000hrs and a 25% loss from 4000hrs usage. With double ended & LEC lamps these hours are 2-3 times longer.

Do I need reflective material on the walls? E.g. Panda film or Mylar?

You don’t need mylar on the walls of your grow tent, but having flat white (panda film), or reflective walls = more light reflection = more plant growth.

How much ventilation is necessary?

Enough to maintain the right temperature and humidity in the centre of the canopy. The leaves should maintain a slight flutter during daylight hours. It is better to have too much rather than too little. Look to replace the air in the grow tent every 2-3 min.

What brand of hydroponic nutrients should I use?

All nutrients will grow plants, but some will be easier to use and less maintenance than others. House & Garden base nutrients are some of the best and easiest to use.

What EC should I aim for? (Electrical Conductivity – measures the salts in the water)

This changes with the growth phase and the grow media, and nutrient brand.

A general guide:   Vegetative: 1.1 – 1.8           Flowering: 1.6 - 2.0

For the last week:   0 - 0.4 EC  To measure EC, get an EC/TDS pen

What pH should I maintain for plants?

The safe range is 5.5 – 6.5, above or below this the plant will not absorb some of the minerals from the hydroponic nutrient. The ultimate level for plant absorption is between 5.5 -5.8 – this is when all the minerals are available at full strength. In the last 3 weeks of flowering us pH of 6.2 – 6.8. This will make more P/K available to your plants.

What temperature should my nutrient solution be?

Between 18 – 22C. If solution is too cold use a water heater. If too hot use a water chiller.

How often should I water?   Use 10-15% more than the container can hold, water during “day”

Perlite  1-2 feeds per day to 3-4/day  Clay balls  15min/hour, then 15min/2 hours

Coco  1/day till 30cm high, 2/day till 50cm, then 3/day

How often should I flush?

Every 7-10 days is recommended when using pure mineral base nutrients (H&G, Cyco, Canna etc.). A small amount of nutrient in flush solution (EC 0.6) will save the plant from any unnecessary stress. Make sure temperature and pH of flush water is correct.

Do not over flush as this can cause inconsistent PPM/EC/CF levels. A general guide is half the volume of water to the amount of media in the pot. E.g. 50L pot = 25L of flush water.

What causes the tips of the plants to burn?

This can be caused by too much fertiliser (too high EC), too much salt in the water, not enough water, lights too close (heat) or not regular flushing. Certain nutrient deficiencies can also cause leaf tip burn.

What causes leaves to turn yellow?   This can be a number of factors:

1.  Nutrient solution too warm (18-22C is optimum)

2.  Low oxygen levels due to lack of aeration

3.  Over watering

4.  Onset of root disease

5.  The pH is too high

6.  Too much salt in the water

7.  Room temps too high or too low

All of these stop the plant from taking up nutrients in the correct quantities and balance.

Why do plants stretch?

Plants stretch when the light is insufficient or humidity is too high. Lack of ventilation is often the cause of high humidity, or too many plants in a small area. A larger fan may help to fix this.

Why are the plants’ roots brown?  Healthy roots are white.

Brown roots are usually those that have been attacked by disease, probably pythium. Another sign is older leaves dropping off. May be caused by over-watering or bacteria in the water. Can be from tank or tap water. Consider “Microbial” to pre-condition your water.

My plants have very small bugs that spin webs, what are they?

These are Red Spider or “Spider Mite”. They can cause severe damage and should be treated by spraying plants when small to prevent an infestation happening. Mite rid for treatment.

There are small black flies around the edges of my pots in the coco around the root system of my plants. Are they a problem?

Yes, Scarid fly can KILL a plant easily if untreated. These flies are also known as fungus gnats. Their larvae chew on and devour the fine root hairs of your plants; this damage increases the risk of waterborne diseases such as Pythium. Eradicator or Scarid 10 are very effective for the treatment of Scarid Fly. A fungicide may be considered for treatment after the Scarid Fly.

What is the brown rotting in the flower buds?

This is nearly always a disease called Botrytis (grey mould).To help prevent this use Silica. If you have this then Eco fungicide will stop the rot spreading through the flowers.

What are the white powdery spots on the leaves?

This is most likely a disease called powdery mildew. This disease spreads by airborne spores that enter the grow tent from the ventilation or when the door is opened. To prevent this try a bit more ventilation and if you have a severe case of powdery mildew try Eco fungicide.

Is it necessary to aerate the nutrient solutions?

Yes, aerating is a good idea as it improves plant health by adding oxygen to the system and protects against stagnant water. With organic nutrients, use a water pump instead of air.