GROW

 

Once you've built your system, use this guide to start growing!

This guide is a set of recommendations only. Each +Farm is going to be operated in different ambient conditions, and growing different combinations of plants. The best way to understand how to manage your farm is through a combination of observation, taking notes, and trial & error. Use the information in this guide as a starting point but adjust it based on the specific conditions that pertain to your +Farm.

 

This guide is written for the home or educational user, not commercial farmers.  If you are a commercial grower, please double check that any suggestions for products or methods in this guide align with methods you’re required to follow.  

 
 
 
 

Seeding and germination

 
 

Plant starts are much easier to grow for crops that will be put into the NFT and DWC systems. Vining crops such as tomatoes and peppers can be difficult to start at home. You may wish to purchase well developed plants at a local nursery. Bring these plants home and water well to make sure they are not stressed.

 

 

Transplanting

 

When ready to transplant, remove plants from pots and lightly remove as much soil as possible, without damaging roots.  If a little bit of soil remains, it should not be a problem.  

 

Once soil is removed, transplant into clay pebbles. After transplanting, allow plants to adjust to their new environment without lights for at least a day.  Make sure to keep pumps running 24/7 to keep roots moist.

 

 

System Maintenance

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Reservoir

The reservoir holds the water and nutrients that will feed your plants.  Understanding, monitoring and controlling what is happening in your reservoir is key to keeping your plants growing well.  

 

Filling the reservoir

Fill your reservoir with cold water and then turn on your system pump.  Allow water to circulate through the system. Allow the system to run with water for at least 30 minutes and make sure everything is functioning correctly.

 
 

EC

EC stands for Electrical Conductivity, which is a measurement of the level of salts in the water. Most plant nutrients (fertilizers) are salts and so adding nutrients to your water will increase the EC reading of your nutrient solution. In other words, EC is a measurement of how much food there is for your plants in the nutrient solution.  

 

EC requirements for plants vary based on numerous factors:

 

 

Here are some recommended EC levels for mature crops (not at seedling stage). Note: these may vary greatly by crop variety. Use these as a starting level and vary accordingly:

 
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Once again, your observations are the best tool for getting the right EC for your plants.  If the EC is too low and plants aren’t getting enough nutrients, plant growth will suffer and leaves will be misshapen or discolored.  If the EC is too high, it will often cause “tip burn”.  This is a yellowing at the leaf tip followed by browning/dying of the leaf tip.
 

 

Adding nutrients

If you are using tap water, it will likely contain a low level of salts.  If you are using filtered water, these salts will likely be removed.  In either case, measure the EC of your water before adding nutrients.  If the EC is 0.1 and your target EC is 2.0, then adjust your target to 2.1 to include the base level of salts in the water.  Add your nutrients (following directions on the nutrient package). Mix well in the reservoir and allow water with nutrients to flow through the entire system for at least 30 minutes.  Then, check EC measurements again and if needed, add more until you reach the right level. 

 

Remember that after each time you add nutrients to your reservoir, you need to allow water to cycle through the entire system to get an accurate reading. If EC is too high, dilute with water or remove water from reservoir and refill with fresh water.  As a reminder: make sure your EC meter is calibrated and probes are clean (see manufacturer instructions).

 
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Adjusting PH

Once your EC is adjusted properly, it is time to move on to adjusting pH.  In chemical terms, pH refers to the ratio of hydrogen (H+) and hydroxyl (OH-) ions in solution.  In other terms, it tells us how acidic or basic the nutrient solution is and uses a scale of 0-14.  Pure water has a pH of 7.0.  Any reading above 7.0 refers to a basic (alkaline) solution and any reading below refers to an acidic solution.

 

Most plants grow best with a pH between 5.5 - 6.5.  As pH leaves that range, chemical changes will lock up certain nutrients and make them unavailable to plants, which may result in a nutrient deficiency.  After filling your reservoir and adding nutrient solution, check the pH and adjust using "pH up" or "pH down" solution. Add a few drops at a time, mix well and let your system cycle for several minutes.  Measure again and adjust until it is in the correct range.

 

Note that pH will fluctuate based on the chemical processes in your system. This is totally normal.  Most people notice that their system pH will tend to drift consistently in a certain direction.  If that is the case for your system, you may want to adjust your pH starting point to the lower or upper end of the pH range so that a day’s drift will keep pH within the acceptable range.

 
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Pump

If you are running a bucket system, begin by irrigating your crops for 10 minutes 3 times per day (10 minutes every 8 hours).  As your plants get older and need more nutrition, especially with crops like tomatoes, you will likely need to increase the number of short feedings per day.

 

Make sure there is always enough water to cover the intake portion of your pump.  If there isn’t, you will likely hear the pump sucking air, which will damage the pump over time.   

  

 

Pump Maintenance

Your pump has a small mesh or plastic filter that keeps larger particles from getting into and clogging the shaft.  These particles can clog your filter, leading to reduced performance and reduced water pressure.  It is important to open up your pump and wash out filters and any gunk that has accumulated every time you clean your reservoir or or whenever you find any problems with water pressure or flow.

 
 

Airstone

The goal of the air stone is to increase oxygen levels in your water.  The air stone should be located in your reservoir and working continuously.  This will allow water circulated by the pump to have a higher level of oxygen. Note: some air stones can be adjusted.  If this is the case with yours, start cultivation with a medium level of aeration and adjust up or down as you see how plants respond. 

 

Light

For vining crops we recommend high pressure sodium lights (HPS). It’s very important that the lights are kept the correct distance from the plants. Too far away and the plants will be starved for light. In response, they will reach towards the light and elongate, making the plants spindly, weak, and unhealthy. Too close and they will be burnt by the heat the lights give off. Some growers attach pulleys to their lights so they can keep them the optimum distance from their plants and raise them as the plants grow.  It is also important to understand where your light is going.  Is it reaching all of your plants evenly?  We recommend starting with your lights 4” (four inches) above your plant canopy (tops of leaves). Make sure light is reaching all plants but leaves are not getting burnt.  Adjust lighting as needed.

 

DLI - Daily light integral

The total amount of light that a plant receives per day is called DLI or Daily Light Integral. The DLI is measured in moles of light per square meter per day. It is very important that plants get enough light to meet their minimum requirement or they will stop growing.  At the same time, most plants only can use a certain amount of light per day and any light they receive that exceeds that amount is wasted. Sunlight is free, but artificial lighting comes at a cost in the form of electricity. It’s very important that the lights are only kept on as long as necessary. The following are DLI requirements:

 
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Important notes about DLI: 

  • Actual light reaching all plants and leaves will differ based on the density of planting.  Thus it is important to measure DLI at the leaf canopy and also in lower areas that don’t get as much light.

  • The number of light hours per day is an average recommendation based on the type of plants. 

  • Use a timer to control your lights (Please see specific instructions for the timer/ smart outlet you are using to program correctly).

  • Electricity rates may vary greatly during day and evening hours in your location.  Running your farm lights at night when energy costs are low may present a big costs savings.  Look into details in your locality.
     

The Environment

Your +Farm may be located in any one of a number of places- classroom, living room, greenhouse, closet, garage- the possibilities are endless.  Each of these locations presents a set of specific environmental conditions.  To thrive, the +Farmer needs to be aware of and understand these conditions as much as possible, and make adjustments to the +Farm in accordance to these conditions.
 

Observing

It is critically important to observe and take notes about what is happening in your farm. Pictures are also a great help in observing changes in plants. Here are some examples of important observations to take notes of:

  • Planting information including dates, seed type and variety (+ lot number from seed packet) 
  • Germination dates and rates (what % of seeds germinate)

  • Plant growth and development notes

  • Leaf shape and color(s)

  • Observations of root development and root color

  • Harvest information

  • Feeding (nutrient) information

  • Signs of pests or diseases

  • Other observations including pleasant or strange odors or anything that you consider to be unusual

Measuring & Understanding

While observing relies on your eyes and ears, you can also measure what is happening at your farm. This can be done manually (i.e. checking a thermometer at noon each day), using a smart device (thermometer/hydrometer that automatically transmits data to an app or your computer) or with a farm monitor/controller that monitors numerous aspects of your farm.  The factors that should be monitored (and recorded) in some way are the following:

  • Air temperature- near plant canopy

  • Humidity - near plant canopy

  • Light intensity and DLI- optional

  • CO2- optional

  • Water temperature

  • EC of water

  • pH of water

  • Dissolved oxygen in water- optional  

How does each one of these factors affect my plants and my +Farm?  The table below shows how these factors influence your plants.

 
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Air Circulation & Fans

Depending on where your +Farm is located, air circulation may or may not be an issue. Even so, it is important to understand why air circulation is important and how it can help your plants grow. Air circulation is important for a number of reasons:

  • Humidity: Stagnant air will encourage humidity to settle on leaves.  Wet leaf surfaces are ideal for the development of fungi.  Air circulation will keep moisture off the leaves.

  • Growth: There is a super thin layer of moisture on the leaf surface (boundary layer).  As this layer dries out, a plant will transpire (through open leaf pores called stomata) and release moisture.  As it does this, it pulls water and nutrients in through the roots and up through the plant.  

  • Air exchange: Plants use CO2 and release O2.  If they are in a confined space, the CO2 levels will gradually lower and growth will be reduced.  Air exchange is important to bring in air rich in CO2 and remove the CO2 poor air.  It will also remove warmer more humid air and replace it with drier, cooler air.

 

 

levated Humidity & Dehumidifiers

Elevated levels of humidity pose a threat to plant health. Some signs of high humidity are:

  • Leaf surface moisture

  • Fungus or mold growing on or under leaves

  • Consistently high humidity readings

There are different ways to lower humidity.  First try circulating your air and exchanging air with an out-of-farm area.  For example, if your +farm is in a closet, try adding a twin fan that will pull dry air in from another room and push out the warm wet air from the grow space.  If air circulation doesn’t work, you may need to purchase a dehumidifier. Dehumidifiers are a very reliable option. Note that dehumidifiers blow out warm dry air which can damage leaves.  Make sure the air is directed in an appropriate way.  Also, they do use a fair amount of energy so this will add to your electrical bill.

 
 

Pests

Small insects will find a nice, cozy home in your new +Farm.  After all, it is warm and moist in there. Common pests include: aphids, caterpillars, spider mites, fungus gnats, whiteflies, thrips and others.  Pests can be identified in two major ways: either by sighting actual pests, or through the presence of eggs or larvae on the underside of the leaves and/or stem of the plant.

 

Pests are often attracted to plant matter, living or dead. It is very important to remove plants from the system when they are ready to harvest and to remove any dead or dying plants from the system. Biomass in the system serves as a food source for pests, so reducing its presence is paramount in preventing infestation. Keep all surfaces clear of plant matter and other debris.

 

Some growers hang a sticky trap or two in their farm.  This is a good way to see what insects are present.


 

Root Health

As the roots develop, take a look at them every so often. If algae is growing on the roots, it could be inhibiting plant growth. If the roots are turning black, a virus called pythium, also known as root rot, may have infiltrated the system. A single case of black roots does not necessarily indicate that pythium is in the system. Generally, pythium causes plants to die and will spread to other plants. The presence of pythium also necessitates a system cleaning and flush.
 

Harvesting

After several months, your plants will be fruiting and ready for harvest! When you have completely harvested your system and it’s empty, it’s a good time to clean your system.


Cleaning

It is important to completely change out the water in your system and clean your system on a regular basis to maintain nutrient levels and prevent diseases. 

 

There are two major reasons to clean your system:

  1. To maintain the correct nutrient levels in solution.  As plants grow they use nutrients in the solution, but they don’t use them evenly, so, over time, the solution ends up with an excess of certain types of nutrients and a shortage of others.  This imbalance can harm plants.  Water tests can be done to determine what is missing and those nutrients can be added back in, or, more simply, you can dispose of old solution and add fresh water and nutrients for your crops.    

  2. To prevent diseases.  Your +Farm may be in a space that is warm and fairly humid.  These conditions are perfect for algae growth and growth of other bacteria and plant diseases.  While algae growth isn’t bad, it does take away some nutrients from your plants, can smell bad, and is a breeding area for fungus gnats.

We recommend you do system maintenance every two weeks when you begin using your +Farm.  As you work with your +Farm and gain more experience, you may decide to do system maintenance more or less often based on what you observe in your farm. Eventually you should be cleaning your system about once a month. 

 

To clean the system, begin by turning off the pump and lights. Remove any plants and set them in a safe location away from foot traffic. Make sure plants are in a cool, shady spot as they can wilt quickly without water. Next, empty all water from the system by draining any remaining water from the grow space into the reservoir and then flushing the reservoir.  Reservoir water is ideally used for watering your potted houseplants or outdoor plants (note: if your plants show any signs of disease, it is best to dispose of water down drain, etc).

 

To clean the system, the main task is scrubbing with a scouring pad to remove algae and other debris. Add warm water (and a small amount of dish soap if desired) to make cleaning easier. Make sure to take the pump apart and rinse out all gunk in pump and clean the filter (this is easiest to do in a sink with a spray nozzle).  Rinse buckets well after scrubbing to remove all debris.  If you have seen any signs of disease in your system, you should follow your cleaning with a hydrogen peroxide flush.

 

Hydrogen Peroxide Flush

The point of a flush with hydrogen peroxide is to inhibit disease that may be in the irrigation lines or the pump. Take a plastic 5 gallon bucket and fill half way with water. Add one bottle of 3% hydrogen peroxide (available at most grocery or convenience stores).  With a sponge, wipe all surfaces with the liquid. Then, disconnect and remove pump from reservoir and place in bucket to soak for at least 5 minutes.  With pump oriented sideways or upside down, turn pump on and allow peroxide flush to circulate in bucket.  Finally, dump flush into reservoir and reconnect pump.  Turn pump on briefly to flush irrigation lines as needed with hydrogen peroxide solution. Once cleaning is done, dispose of this water in a floor drain, sink, or toilet. Finally, refill the reservoir with water, add nutrients, balance pH, add plants, and turn on the pump and lights again. Always monitor your system after cleaning to make sure everything is working properly, there are no leaks and there is sufficient water. Note: Hydrogen peroxide is not toxic to plants and can be beneficial by raising the oxygen levels in liquid.  3% hydrogen peroxide may have other chemicals to stabilize it and that is why we recommend disposing of the peroxide mix after running it through your system.

 

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