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How to Grow Hydroponic Strawberries

by Max on Wed, 04/04/2018 - 16:56

Fruit plants are not considered to be the easiest options for hydroponics beginners. This is largely due to the increased input requirements, and higher maintenance and care involved.

But strawberries are a bit of an exception to this rule. They thrive in hydroponic grow systems and can produce large amounts of fresh fruit all through the year.

Once you have gained some experience growing herbs and greens, it is the right time to try your hand at growing strawberries. In this article, we will examine all the core factors of hydroponic strawberry cultivation, from seeds to harvesting.


Growing Strawberries from seeds or runners?

Planting strawberries from runners
Planting strawberries from runners

Strawberry seeds can be used to create new plants. But if you are starting from scratch, and do not have an outdoor garden, this is not a good idea.

Strawberry plants grown from seeds take time to mature, well over 2-3 years! So if you want to harvest fresh fruit this year, that option is out of the question.

Plants grown from seeds may not show the same qualities as the fruit they are derived from either. 

Soil also hosts a lot of dangerous microorganisms and pests that can kill or stunt your strawberry crop. Farmers used to (and still do) spray a dangerous and banned pesticide called methyl bromide on the soil before planting strawberries.

Runners are the preferred option for propagating strawberries, especially in hydroponics.

Some plants have stems that grow horizontally instead of vertically. These stems can sprout roots and create new plants.

Such stems from mature strawberry plants are harvested their roots are allowed to grow. They are then chilled (to mimic winter temperatures and create flowering) and stored.

These frozen, virus-tested runners are usually available in local nurseries and gardening stores.


Strawberry Type: Short-day Vs. Day Neutral Vs. Everbearing

Strawberry type

Based on their light requirements and growing seasons, strawberries can be divided into three varieties:

Short Day/June Bearing

These are among the most numerous varieties, usually found in outdoor cultivation. They are called short day because they start flowering during the shorter days of winters.

And after flowering, these plants typically bear fruit by early spring, hence the name June bearing strawberries.

June bearers typically take a long time to produce one heavy harvest per year. You can get them to produce more batches in hydroponics, but it takes more inputs, care, and effort.

Benton, Allstar, and Annapolis are some popular June nearing strawberry cultivars you may be able to find in your local nurseries.

Day Neutral

Day-neutral plants can produce fruit all through the year as they are not severely affected by changing light and temperatures. These are the most popular varieties for greenhouses and hydroponics as they are easier to manipulate.

Day-neutrals are modern cultivars developed from the original strawberry varieties called Everbearing strawberries. They were developed sometime in the 1960s.

Day-neutrals can be identified by their ability to bear fruit all through the year continuously, from summer well into the fall.

Seascape, Quinault, and Hecker are among the more popular day-neutral strawberry cultivars.

Everbearing

These are the original multi-crop strawberry variants. Day-neutrals were developed from these originals in the ‘60s at the University of California.

Everbearing strawberry plants will have at best, two or three crops in a growing season. In contrast to day-neutrals, these older variants tend to have lower fruit yields.

If you want high fruit yields, day-neutrals are a superior alternative to everbearing cultivars. Both these plants will stop producing fruit in the high summer heat.

Picnic, Albion, and Laramie are some popular everbearing strawberries.


Strawberry Growing Season

Strawberry growing season
Strawberry growing season will be mainly affected by the seed types and the availability of runners

In hydroponics, there are no strict growing season requirements. Your growing season will be mainly affected by the availability of runners, either in stores or in your outdoor gardens.

Usually, stores these days have a year-round supply of frozen runners. But if they don't, runner stocks are highest in late winter and early spring seasons.

But once you start your hydroponics strawberry crop, you can propagate runners from these plants. They can be planted all through the year.

Runners cut from homegrown plants will require some cold stimulation. You can achieve this by placing them in the refrigerator for anywhere from 6-12 weeks.


Light Duration & Pollination Requirements

As already mentioned, strawberries are either short day or day neutral. This means that they can thrive with shorter light durations.

Anywhere between 8-12 hours is usually more than enough for proper growth and yield. There is no need to vary your light schedule in different stages either.

But pollination is a key concern. Strawberry plants contain both the male and female parts on the same plant.

In outdoors cultivation, pollination is handled either by bees or the wind. In indoor hydroponics, you can stimulate this by gently brushing your hands across the open flowers.

Ideal Temperature Requirements

Measuring plant temperature

Strawberries prefer cool to warm temperatures. The ideal range is somewhere in between 60 - 80 degrees Fahrenheit, or 15 - 27 degrees Celsius.

The optimum daytime air temperature is somewhere in the middle, at around 20 degrees C, according to the University of Arizona.

According to their College of Agriculture sources, lower night temperatures between 10-12 degrees may result in increased fruit yields.

In the longer term, strawberry plants prefer to hibernate for anywhere between 2-5 months in winters. You can store the plants wrapped securely in plastic in a refrigerator if your area doesn't have very cold winters.

Nutrient Requirements

In hydroponics, it is easy to get appropriate nutrient mixes for specific plants from your local store. Strawberries require both key nutrients as well as trace elements:

Essential Nutrients: Nitrogen, Potassium, and Phosphorus (NPK) are essential for basic plant survival. Nitrogen is for cell growth, phosphorus for the roots, flowers, and buds, and potassium is for photosynthesis.

Trace Elements: these include iron, manganese, zinc, copper, molybdenum, cobalt, and chlorine, among others. Lack of these elements will result in poor plant growth.

Most hydroponics nutrient mixes contain these trace elements, as you don't have the support of soil in hydroponics. So as long as you are using a nutrient mix intended for hydroponics, you don't have to worry about nutrient deficiency.

EC & PH Levels

There is an optimal pH level for the nutrient solution when growing strawberries. This is generally in the range of 5.8 - 6.2.

The pH level of the nutrient solution can be manipulated by either adding potassium hydroxide (to increase pH), or phosphoric acid (to decrease pH).

In hydroponics, the nutrient mixes contain minerals that affect the water electrical conductivity levels. The accumulation of mineral salts can affect strawberry growth.

You can use EC meters to measure electrical conductivity, which is measured in milliSiemens/cm, or mS/cm. Scientists also use deciSiemens/cm (dS/cm), which is considered identical to milliSiemens.

For strawberries, the ideal EC is 1.0 dS/cm, or lower in greenhouses using soil or soilless growing media. In hydroponics, this can vary, depending on the technique, to anywhere between 1.4 - 3.0 dS/cm.

You can use fresh water to flush the excess salts at the roots if they exceed these limits.

Hydroponic Systems For Strawberries

Strawberries are incredibly versatile as far as hydroponics is concerned. This is mainly due to their small root systems.

Runners can thrive in a wide variety of techniques, ranging in complexity from relatively simple and mobile to more complex and stationary grow systems.

They include:

  • Deep Water Culture
  • Ebb & Flow
  • Nutrient Film Technique
  • Drip Irrigation
  • Wick system
  • Aeroponics

Of these, deep water culture is useful if you have space to grow a large number of plants in a single-tiered system.

Others are much more suited for compact multi-tiered grow systems. As a result, commercial and hobby growers prefer any one of these different techniques.


Growing Strawberries Using Wicking - A Step-by-Step Guide

If you are a hydroponics beginner, wicking system is the best option (with the possible exception of deep water culture). It does not require water pumps or complicated irrigation setups.

Basic Components

  • A reservoir for the nutrient solution. It could be a large 5-gallon tub or bucket.
  • Growing container - you can either use individual pots, or a single larger trough or tub. Make sure that the growing containers can rest securely on top of your reservoir.
  • Wicks - use strips or ropes made of nylon, rayon, cotton, wool, or PU threads
  • Growing medium: strawberries need well draining and aerated growing medium. Do not use coco coir or peat on their own. You can try a combo of perlite-vermiculite or coco coir mixed with perlite/vermiculite.
  • Nutrient mix - buy an appropriate hydroponics nutrient mix from your local store.
  • Strawberry runners or rootstock - if using rootstock from soil-grown strawberries, take particular care to clean off the soil entirely from the root system, and disinfect the plants. 

Method

  • Prepare the growing medium by soaking it in pH balanced water for 30 minutes.
  • Fill the grow container with the growing medium, up to two-thirds.
  • Fill the reservoir with a mix of nutrients and water. Check the water for optimal pH and EC levels.
  • Prepare the wicks by cleaning them thoroughly in pH balanced water.
  • Place multiple wicks between connecting the growing pots with the reservoir. The wicks should touch the growing medium, and dangle freely deep into the reservoir.
  • If using individual pots, have two wicks per pot. If using a single trough or pot, have multiple wicks (more than 2-3).
  • Securely place the grow container over the reservoir.
  • Place the strawberry plant inside the container. Spread the roots evenly into the growing medium.
  • Cover the roots with more growing medium. Do not cover the crown of the plant.
  • Check the reservoir daily for water levels. Refill the container when the level gets low. Check the pH levels and EC levels when refilling the container with a fresh nutrient water mix.
  • Flush the growing medium using fresh water once per week to remove accumulated mineral salts.
  • Place the strawberries under sunlight (if growing outdoor hydroponics). Use grow lights if the grow area is indoors. Ensure that the plants get adequate light.
  • When flowers appear, pollinate the individual plants using your fingers.
  • Harvest fruits only when they are completely ripe and red. Unlike other fruits, strawberries do not ripen once plucked. 
  • Clip additional runners from adult plants if you want to grow more strawberries all through the year!


Conclusion

Strawberries are special for hydroponics farmers. You can easily get a full supply of the fruit for your household all through the year using indoor hydroponics.

Experiment with different techniques to figure out which one works best for your grow room. Always remember to grow vertically for maximum yield, as the small plants are ideal for this type of grow system.

 

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