Propagation in the plant world is a beautiful thing. Both a science and an art, propagation is the delicate and, quite arguably, magical process of plant reproduction. While many forms of propagation have been experimented with throughout the history of horticulture, the classic methods of planting seeds (sexual reproduction) and making clones (asexual reproduction) remain the most popular, simple and reliable processes in the hydroponics industry.

What is sexual propagation?

Planting from seed is nature’s way of sexually reproducing a plant. It occurs when the pollen of a male plant lands on the flower of a female plant, fertilizing its ovaries and producing seeds. The seed is a well-protected pod that contains the genetic characteristics of both parent plants. When the seed is planted, or sown, it develops into a new plant, or strain, that displays traits from both plants from which it was produced.

Planting seeds

  • Seeds can be planted directly into the soil or medium in which they will be grown, or they can be started in a starter cube or propagation tray.
  • Starter cubes are designed to help sprout seeds and they are perfect incubators for new seedlings.
  • Many growers soak their seeds in a warm, dark location for a day or so before planting. This enables the plant to soak up water and soften its hard casing prior to being sown.
  • To plant the seed, insert it into a start cube or planting mix about ¼ in. below the surface of the medium. Gently cover it so it is not directly exposed to light.
  • Secure a humidity dome over the starter tray.
  • Place the tray or potting container in a window that gets indirect sunlight or under a horticultural-grade fluorescent light fixture.
  • Keep the temperature inside the humidity dome around 75 to 80°F, and the seeds should sprout in five to seven days.

What are some advantages of starting from seed?

Identifiable lineage

Seeds purchased from a reputable distributor should have listed characteristics. Seeds harvested from healthy fruits and flowers should display dominant traits from the selected varieties.

Vigor/yield

Plants started from seed tend to grow with robust strength and produce high yields. Strains degrade over time and starting from seed is great way to revitalize good producers.

Breeding

Growers have the option to cross (or, breed) two strains that display desirable traits to create a new strain. This involves pollinating the female plant with the male plant to produce a new seed.

Overall plant health

Plants started from seeds are clean and there are fewer instances of the disease, pests, and mold often associated with clones.

What are some disadvantages of starting from seed?

Cost/availability

Some seeds are expensive, rare and sometimes hard to obtain.

Time

It often takes longer to reach harvest when starting from seed. The process involves planting the seed, seed germination, vegetative growth and then determining the gender of the plant.

Unpredictability

There is the possibility that not all seeds will sprout (or, germinate). There is also a high possibility that not all seeds will be fruiting or flowering female plants. When determining the sex of plants started from seeds, it is imperative to remove male plants upon identification.

One male plant in a group of females could pollinate all the plants, virtually turning a viable flower crop into a seed crop. Some companies sell feminized seeds, guaranteeing a certain percentage of the seeds to be female; however, even those seeds can contain an occasional male.

What is asexual propagation?

Asexual propagation techniques include cloning, grafting, layering, and tissue culture (to name a few). Taking clones (or, cuttings) from a mother plant has established itself as the most reputable form of asexual propagation amongst growers in the hydroponics industry.

Making clones

Clones are easy to make and root quickly under proper environmental conditions. To make a new clone:

  • Select good strong branches from a healthy mother plant.
  • From the tip of the branch, count down about four to five nodes and—using a sterile scalpel—slice the branch at a 45-degree angle directly below a node.
  • Slice off the two leaves directly above the cut and immediately dip the cutting into cloning/rooting gel. It is important to dip the cutting into cloning gel just after being cut to avoid the cut site from developing an air bubble (or, embolism) that could kill the new clone.
  • Gently insert the cutting into a moist starter cube and cover with a plastic humidity dome.
  • Place the cutting under a horticultural-grade T5 light fixture and keep the temperature around 70 to 75°F.
  • Using a rooting gel with a strong concentration of rooting hormone should ensure healthy fuzzy white roots in about seven to 10 days.

What is cloning gel?

Cloning gel is a thick gooey gel infused with a rooting hormone to aid in the propagation of clones from a mother plant. The rooting hormones in the gel essentially tell the plant to make roots at the cut site of the plant where it has come into contact with the gel. New roots form on the cutting and eventually grow into a whole new plant with the same genetic characteristics as the mother plant from which it was snipped.

There are many brands of cloning gel available in the horticultural industry, so find a reliable rooting gel and stick with it! Look for formulas that contain the hormone IBA (Indole-3-butyric acid). It is also important to select a thick water-based gel that does not contain colorants or dyes.

What are some advantages to starting from a clone?

Quicker turn around

With less veg time, starting from a clone usually takes less time to reach harvest, increasing the amount of crops that can be grown over time.

Genetically identical

Because clones are genetically the same as the mother plant, growers can be sure that clones are female and, thus, not have to wait to determine their sex. Note: female plants under stressful environmental conditions, such as light leaks in the dark cycle, can turn to hermaphrodites and produce seeds.

Quickly reveal strain characteristics

Since clones grow so rapidly, they will quickly display their defining traits, such as scent, growth rate, internodal spacing and quality of rootstock.

Uniformity

Clones tend to grow at a more uniform rate than seeds.

What are some disadvantages to starting from a clone?

Availability

It is sometimes difficult to find specific plant varieties as clones.

Environmental problems

Clones are susceptible to inheriting any types of disease, pest problem or infection that the mother plant might have been exposed to.

Sensitivity

Clones are more sensitive to light and have a higher probability of experiencing burns or shock.

What mediums are best for propagation?

There is a wide range of growing media that work well for plant propagation. These media include soil, soilless mixes, perlite, vermiculite and stonewool. Peat-based starter cubes work excellent for both seeds and clones. They are a popular choice for many growers because once the plant has developed roots, the whole cube can be transplanted into soil or any hydroponic medium. They are compatible in organic gardens and are completely biodegradable.

Look for peat-based starter cubes that come sealed so humidity levels are prime for planting. Make sure the cubes are slightly moist for planting seeds or clones. Once a new seedling or clone starts to show vigorous healthy white roots, it is ready to be transplanted. Carefully transfer it into a high-quality medium of choice and the new plant should shoot off into explosive vegetative growth!

Finally, healthy, high-producing plants rely on good seed stock or healthy clones taken from a stable mother plant. Choose genetics carefully and use premium grade propagation products and your crop should produce a bountiful harvest that is not only delicious, but also nourishing to the mind, body and soul!