Perlite has been known for years as soil additive and growing medium, used to increase aeration and soil drainage. Perlite belongs to mined materials, originating from volcanic glass. This natural material breaks into multiple tiny bubbles, when heated rapidly above 1600 deg. F.

Being one of the best hydroponic growing media, perlite is usually used by itself or as a component in mixtures with other mediums. Often it is vermiculite, which is mixed with perlite in equal proportion. Besides, perlite is often used as the major ingredient of soilless mixtures. Perlite is characterized with good wicking ability and thus it is commonly used in wick-type hydroponic systems. Finally, perlite is a relatively inexpensive growing medium.

The biggest weak point of perlite is that this material cannot hold water long enough. It means that perlite growing medium dries out quickly and requires more frequent watering. Besides, perlite dust can be harmful for human health, and it is recommended to wear a protective mask while working with it.

Vermiculite

Being another mined material, vermiculite resembles mica rock in its natural state. Under the influence of high temperature, this material breaks down into small parts just like perlite.

It is a common practice to use vermiculite in conjunction with perlite in hydroponics systems, since these two ingredients complement each other. Vermiculite is capable of retaining high volumes of moisture (up to 200% – 300% of its own weight); and since perlite cannot hold water that well, it is easy to balance your growing medium, so that it holds water and nutrients, while still supplying enough oxygen to plants roots. Usually, a 50/50 mixture of vermiculite and perlite is used for hydroponic systems of drip type, as well as for ebb and flow systems. Similarly to perlite, vermiculite is also an inexpensive growing material.

The major drawback is that vermiculite retains too much water. This material should not be used by itself as the only component of growing medium

Light Movers

Of course, none of the indoor lighting systems can substitute the sunlight. Artificial light is much less intense, so it is necessary to place it close to the growing plants. However, this is also not that good, because it may cause overheating of the growing medium or even burning of the plants. Besides, when light is close to the plants, it may lead to the so-called pyramidal effect, when the plants, closest to light source, grow much quicker than those at the distance from the light bulb.

Moving plants around may be a solution for that problem. However, it is not that always easy to move plants, sometimes it is practically impossible. The only way out in that case is to move light around the plants.

Special devices, called light movers, exist to move light. There are two types of light movers: linear and circular. Linear light movers move light lamps back and forward, while circular light movers can move 2 or 3 grow lamps around the circle. Linear movers can be used in rectangular shaped garden, while circular devices are suitable for round gardens as well.

Light movers help to prevent plants burning, and, at the same time, they help to increase the area, covered with light, and to balance the light received by plants that grow at different parts of the garden. Unlike stationary light, light movers provide lighting of the plants from many angels, resulting in better light distribution.

The most essential of all nutrients for leaf and stem development. Nitrogen consumption depends on a plants growth cycle and in a vegetative growth phase of plant nitrogen consumption is greatest. Hydroponic nutrients solutions labeled as “grow” or “flower” contains more concentrations of nitrogen. Nitrogen deficiency is the leading cause of plant growth in indoor hydroponic garden systems. Yellowish, soft and weak plants and leaves are tell-tale signs of nitrogen deficiency.

Half-strength nitrogen solutions are ideal for plants between growing phases. This will prevent plant stretch while it’s switching its energy over to flower development. Normal feeding is resumed once the plant reaches the flowering stage.

Phosphorous plays a major part in root and flower development. Phosphorous deficiency signs are slow and stunted plant growth. Phosphorous is crucial to a plants flowering stage. “Bloom” type formulas contain a 0-50-30 concentration, containing no nitrogen and high levels of phosphorous and potassium.

Potassium (K)

Different in action from the previous two nutrients, it doesn’t feed the plant directly in any specific stage of growth. It merely facilitates plant intake of other primary and secondary plant nutrients. Potassium deficiency cause irregular plant growth and susceptibility to pests and disease. Potassium inhibits fruit production and should be lessened during this stage.

Calcium (Ca)

Facilitating and filtering the absorption of other nutrients Calcium is one essential nutrient. It is also a natural base that increases the pH level is needed. Commonly used in the vegetative phase of plant growth, calcium consumption is decreased during the flowering stage.

Mainly for chlorophyll production in photosynthesis, deficiency causes yellow leaves.

Yellow leaves are a sign of sulfur deficiency and are only used in small amounts.

Used in small amounts, iron deficiency is similar to sulfur deficiency. Yellow leaves are the general signs of deficiency. High pH causes iron absorption problems so constant monitoring is advised.

Mainly for nitrogen absorption and converts nitrates to ammonium

Boron (B)

Facilitates carbohydrate transport in the phloem, it is not essential and maybe disregarded. Boron overdose causes plant kill, it is not found in regular soils and only supplemented.

Nutrient solution is made of water with dissolved fertilizer. It is preferable to have good quality water to be mixed with the fertilizer, the amount of which is always indicated by the manufacturer. It is very important to check and adjust if necessary pH level of nutrient solution with liquid pH adjusters. Usually, pH level of the nutrient solution depends on the plant; however, most often it is between 6.0 and 6.5 for the majority of the starter cubes, with the exception being Rockwool, which needs pH level of 5.5 to 5.8. Fertilizing young plants, a gardener should use a nutrient solution as weak as ¼ to ½ of the full strength suggested by the manufacturer. Only plants older than two weeks can be fertilized by the full strength nutrient solutions. It is recommended to keep the growing medium moist, but not too wet or soaked with the hydroponics nutrient solution.      

How to Transplant Seedlings

The seedlings should be transplanted when the roots have grown out of the starter cubes. It is just necessary to place the seedling along with the starter cube on top or into the permanent growing medium, which can be any hydroponic growing medium or just soil. 

Notes in taking cutting for clones

Cutting, as a method of plants propagation, works well only if every step of the procedure is done correctly. Otherwise, experiments may result in devastating consequences. Though, when done properly, up to 95-100% of all cuttings grow successfully, it is still may be a good idea to take twice as many cuttings as needed, if you are making first steps in growing cuttings. 

One of the hints to increase chances in successful outcome is to use distilled water, while growing cuttings. Generally speaking, this is one of the most reliable and proven methods of plants propagation, suitable for most of the plants. Other examples of propagation techniques are dividing, air layering, and tissue culture. It is even possible to root cuttings without the use of any growing media in specific hydroponic systems. After forming the first roots, such cuttings are usually transplanted into any type of preferred growing media.

Defining the best growing medium is pretty challenging and disputable. It is a matter of personal likes, preferences and exact growing needs or requirements in most cases. It is like choosing a car: everyone picks the one, which suits his/her personal likes and requirements: someone chooses a small economic car for city traffic, and someone prefers powerful SUV to conquer sand and morass. Just like choosing a car depends on many factors, while choosing a growing medium it is also necessary to consider many variables, for example, what type of system is used, what plants you are going to grow and under what environmental conditions. Though there are a great variety of factors to consider while choosing a particular growing medium, it often comes to price, availability and personal preferences. 

The most common types of growing mediums as well the description of their key advantages, disadvantages, their basic characteristics and tips on general use are specified below.

Oasis cubes

 Expanded Clay Pellets

 Rockwool

Coconut Fiber

 Sand

 Gravel

Perlite

 Sphagnum Moss

 Water

Vermiculite

 Fiberglass Insulation

 Saw Dust

Soilless Mix(s)

 Air

 Lava Rock

Oasis cubes

Oasis cubes are lightweight cubes, which serves the best for plants propagation from seeds or cuttings. Pre-formed oasis cubes are commonly used by hydroponic gardeners. This type of growing medium features neutral pH level and can hold water very well.

Since oasis cubes are usually used at the first stages of plant growth, they are usually not larger than 2” x 2” inches in size. It is very easy to transplant such cubes into any type of hydroponic system, growing medium or even into the soil. 

Expenses made at the start of the project can be offset by the advantages in the long run. Fertilizers with their ever rocketing cost are major source of expenses in plant cultivation. Plants only take the nutrients they can absorb so maximum nutrient absorption without the risk of putting too much fertilizers is eliminated. But the risk of putting too much nutrients which leads to root damage remains, so proper nutrient feeding is advised.

All in all, the hydroponic system of growing plants increases plant production and quality of the crops. Nutrients essential for plant growth are readily available, proper ratio and distribution is assured resulting to better efficiency. Pesticides and plant diseases can be avoided as no soil is needed. Soil is an ideal medium for infection and disease, so harm to both plant and the individuals are reduced. Expenses are also reduced as pesticides are eliminated so overall; cost effectiveness is enhanced and make hydroponics a more economical way of growing plants.

For the environmentalist, the hydroponic system of growing plants also presents a more desirable and alternative way of plant production. The effects of growing plants through this new system has proven to be less polluting as it totally removes the need for pesticides and leaves the soil free from contaminants. Scientifically tests also show that plants grown through the hydroponic system contain more vitamins and minerals compared to those grown through fields.

Productivity is also increased with the use of Indoor hydroponic systems. Limited spaces for plant cultivation are maximized because smaller pots are used. Indoor hydroponic systems utilize different types of automated watering systems like drip, pumps and other means, allowing for a low maintenance operation. Spaces not available for plant growing can be utilized and together with regular soil gardens or fields, maximize each growing season.

Types of Indoor Hydroponic Systems

Wick or NFT

The system most often used, operated and maintained with the outmost ease. It requires very little setup and maintenance. This is done by simply cutting a hole in the bottom of the pot and a wick is inserted. The wick’s other end connects to the water reservoir below the pot.

Reservoir or Ebb and Flow System

A growing medium is directly placed into a pan filled with water and nutrients. It is easy to maintain, the pans contents needs only to be replaced every few days in order to maintain an effective system. Root adsorption is maximized with root surface in contact with the water, oxygen and nutrients are readily absorbed.

Drip Systems

The most common of all systems, drip systems are the most likely choice of hobbyists and professionals alike. The nutrient solution is kept in a container below the plants and is distributed by a pump to each plant thru a drip irrigation system. One type would be the Recovery type system; excess nutrients are recycled and channeled back into the reservoir. Another would be the Non-recovery type where excess system is not funneled back into the system, one advantage of this is that is a low maintenance system. Ph and nutrient concentration remains stable but is not as economical as the recovery type system.

Aeroponic System

Technically, the aeroponic system is the most advance of the three. Plants are suspended either without a growth rock or growing mediums. This permits the plant to breathe more air through the roots. Nutrients and water are introduced by timed misting. Root health is maintained by a timer and is set at intervals of a few minutes.

Hydroponic nutrient solutions are normally sold in concentrated forms. They are then added to the water supply with a specific ratio. Ideally, 150-600 parts per million consists a normal concentration of hydroponic solution. Normally sold in two or three parts because direct combination is not possible. Remember to mix nutrients into water first before combining, never combine two nutrients together.

 How Much Hydroponic Nutrient Solution?

 There are specific proportions for each plant type and phase of its growth. Advances in nutrient solutions have greatly improved the precision of concentration based on a plants growth stage. Hydroponic nutrient solutions are usually sold in “grow” or “growth” formulas for the vegetative phases and “bloom” or “flower” for the flowering phase of the growth cycle. Remember to switch to the bloom formula during the bloom stager to increase yields exponentially and max out your plants capacity.

In poor growing conditions weak nutrients are recommended. Low lighting, overheated gardens, crowding and root bound plants. Weak nutrients are also ideal for newly rooted cuttings and for transporting plants or when they are in the transition of growth cycles.

Normal, healthy plants can be used with regular strength solutions in ideal growing conditions. Increasing nutrient solutions could be utilized to enhance efficiency of your gardens. An ideal system such as high quality lights, proper aeration and ventilation when present is the only instance wherein you could increase the level of nutrient solutions to improve plant growth. Gradually increasing the nutrient solution is advised as not to burn the plant roots.

Various additives are also available for optimum plant growth. Maintain good grow logs or records of types of additives used, when applied and results. This enables you to measure its effectiveness in the future. If there are any negative effects with experimentation, flush or rinse your hydroponic system immediately.

 How to measure Hydroponic Nutrient Solutions

 Electronic conductivity of dissolved minerals in the water is the usual basis for determining nutrient solution. Parts per million (ppm) is the unit of measure. But this is just a general way of measuring conductivity in the solution and not the actual strength of individual minerals. This is the main reason why hydroponic nutrient solutions are sold as a mix of 3 parts. Once the desired mix is achieved it is very convenient to change the concentration to achieve proper conductivity.

Overuse of Hydroponic Fertilizers

 Flushing out your growing medium is the first intervention once any signs of over fertilization are observed this is to prevent further damage to the plant. Clean water is used for flushing until signs of nutrient deficiency are observed in the plant. Normal feeding and schedule is then resumed. Some hydroponic systems require a top down flushing to completely clean out the plant.

2 weeks before your expected date of harvest, flushing is recommended for the plant. It is done to leave your harvest free from the hydroponic nutrients solution taste. 

Preparing hydroponics starter cubes for the use depends on the type of the cube you have. For example, Organo-Cubes are ready for use, while Oasis cubes and Peat pots should be soaked in water (with pH adjusted to 6 – 6.5) before use. As soon as the cubes are saturated with water, they should be left to drain a bit, and then they are ready to be used. Rockwool is different, since it has high pH. Therefore, it should be soaked in water with pH adjusted to 5.0 in order for this acid solution to be balanced to the pH level required for the plants normal growing. These cubes should be soaked in water approximately for 24 hours, followed by the drainage prior to the use. 

Having done these easy manipulations, the seeds can now be planted. Small holes about ¼ to ½ inch deep should be made in the cube with a tip of a pencil or a pen. Then seeds may be put into the holes and covered with some cube material from around those small openings.

It is best to keep the seed cubes moist, but not wet, always preventing them from staying in the water. The cubes do not need light until the seeds germinate. Similarly, no nutrients are necessary for the plants until they have their first true leaves developed. In this case a diluted nutrient solution

Structurally, metal halide lamp is a vacuum glass tube. There is also an arc tube inside, filled with mercury and other metals in iodine form. Under the influence of electric current, those metals start to generate light and heat intensively. Though metal halide bulbs can be either transparent or coated with phosphorus, the first type is more preferred for the indoor gardening, since it produces very bright light.

There are different sizes of metal halide lamps, starting from 70watts and finishing with 1500 watts. However 250w, 400w and 1000w are modifications, most commonly used in hydroponics systems gardening. In order to make MH light to work, it is necessary to use a ballast, designed for a particular bulb size. Ballast is, in fact, a transformer, which decreases voltage to some predefined amount.

The lamps can work only in the positions they were designed for. Those marked with BU or BD should be used only in vertical position; while those lamps, which carry HOR sign, are for horizontal application. Besides, there are also universal (U) lamps, which can operate in either position. 

There are also many different styles of metal halide lamps available on the market today. Along with typical or regular MH bulbs, there are also Super Bulbs, which can produce up to 10-12% more light than ordinary bulbs.

Regular metal halide bulbs should be replaced after about 18 months or 9500-10000 hours of use. Super bulbs are less durable and should be replaced more frequently – approximately after 12 months or 6500 hours of use. These recommendations apply if grow lights will work 18 hours daily.

Light is essential for health of your indoor plants, but choosing a proper grow light may be challenging and always requires thorough considerations. Grow light fluorescent offers the benefits of high effectiveness, no heat generation and full spectrum of light. For comparison, incandescent bulbs also produce a lot of light, but at the same time they generate a lot of heat, which is not always beneficial for indoor plants.

Each stage of plant development requires a particular light. When the plant is in its growing stage during which stem, branches and leaves develop, it is the best timing to use metal halide lamps for they produce blue spectrum light. However, when plant forms flowers and fruits, it is better to use high-pressure sodium or HPS lamps, which provide red light spectrum. 

The only downside of MH and LPS lights is the heat generated by them. Heat is not good for plants and soil. To prevent overheating, special cooling fans may be required.

 diodes or LEDs, introduced in early 1920s, have debuted in hydroponic gardening as grow lights only recently. In comparison to metal vapor lights, LED lights offer a lot of benefits with the initial cost being their only disadvantage. However, these grow lights are more cost-effective in the long run, having the average life time of about 100 000 hours vs. 15 000 hours of other lights. Besides, LED lights consume less energy, providing energy saving up to 80% in comparison to fluorescents and metal vapor lamps. Furthermore, LED lights do not generate heat, and, therefore, they need no additional cooling and ventilation.

 In order to increase plant growth and productivity it may be necessary to use certain additional accessories, such as reflectors, which help to increase light intensity and make it more balanced, eliminating any “hot spots”.

 Another key component of the grow light system is ballast, which provides energy. While fluorescent light fixtures have built-in ballasts, the other types of grow lights, namely metal vapor and LED lights require remote or external ballasts. Digital ballasts are important components, so it’s better not to save money on them. It is recommended to choose domestically produced digital ballasts instead of old magnetic coil types or those imported from China. In addition to being more reliable, expensive digital ballasts are equipped with additional features, such as short circuit or defective bulb detection.

 Hydroponic gardening belongs to the most common techniques to grow plants and flowers with no land required. While building hydroponic system, sooner or later one faces the necessity to invest in high quality grow lights. A lot of people give their preferences to HID (high intensity discharge) lights equipped with digital ballast. These types of lamps provide the most natural light similar to sunlight, which is especially important for successful indoor plants growing. However, there are certain differences between HID lamps worthy to know.

 In general, five types of HID lights exist. They are mercury vapor, xenon short-arc lamps, metal halide, low-pressure sodium and high-pressure sodium lights. Among these metal halide and high-pressure sodium lights are the most preferred types.