History and Development
Although they've been known to European botanists and horticulturists since the 1700s, Gerberas didn't really hit their stride until the early to mid 1990s with their aggressively cheerful Frisbee-esque flowers showing up in flower shops and supermarkets worldwide. Not unlike Alstroemeria, they went from fairly obscure to widely available in a very short period of time. This has given the Gerbera a similar image problem to Alstroemeria. We don't have a sense of nostalgia around either crop. We only know them as cheap imported supermarket flowers, not as something precious that Grandma used to grow. However, by all measures Gerbera are excellent cut flowers. They are long lasting (or certainly can be), they have long stems that are free of foliage, come in a wide range of colors, and in an increasing range of colors and shapes. We humans love round flowers and we love flowers with lots of petals. Peonies, Ranunculus, Dahlias, Roses, Zinnias and many others meet these criteria. The notion of classifying "good" flowers vs. "bad" flowers is preposterous. It's time to reconsider the Gerbera.
Gerberas have one single caveat: the cut flowers require excellent sanitation. Their stems are easily clogged by bacteria, blocking the uptake of water and wilting the flower. If you are lazy about washing buckets or unwilling to educate yourself regarding proper post harvest handling, move on–Gerberas are not for you. I view them as the canaries in the coal mine. If your Gerberas are hydrating and lasting well, then you have good habits that will benefit all of your cut flowers. More on post harvest later.
Gerberas are native to subtropical Southern Africa. They grow at a bit of altitude which gives them warm sunny days and cooler nights. They can take a light frost, but they are not truly winter hardy colder than zone 9. If you are able to heat them in the winter, they can be kept in constant production for years at a time. Alternatively, they can be allowed to go somewhat dormant in the winter. I have kept them at a minimum of 35 in the winter time. At these temperatures they just sit there waiting for the increased light and warmth of springtime, at which time they jump back into production.
Soil or Pots?
You can certainly grow Gerberas in soil, but there are some things to watch out for. The big concern is Phytophtera, a root rot pathogen. When grown commercially in soil, either steam sterilization or chemical fumigation are used. Neither of these techniques are widespread in the US. Steam sterilization requires bulky and expensive equipment (and lots of energy to operate). Methyl bromide is the chemical traditionally used in soil fumigation but it is highly toxic and largely illegal these days. Some benefit may be attained by using a pre-treatment with bio fungicides or conventional fungicides, but I am unqualified to make specific recommendations.
The best way to avoid soil-borne pathogens is to not use soil, or grow in pots using a sterile media. Pots offer a number of benefits beyond the simple fact that you can fill them with a sterile media. Gerberas have very long leaves that will hang down over the edge of a pot as the plant matures. If grown in a flat soil bed, these leaves would become damaged by foot traffic or would come in contact with soil making them more prone to pathogens. Pots can often be elevated off of the ground allowing excess water to drain freely, and keeping them away from soil. Commercial growers in Holland grow in pots, elevated about 18” off of the ground. This allows for easier harvest for the grower, allows the leaves to hang over the pots, and allows for uniform drainage. The excess water can be collected in gutters and recycled, or diverted to other crops.
Pots of around 1 gallon in volume are recommended. Gerberas are adaptable to a number of different types of media. Standard peat/perlite media work well, as do those based on coconut coir. Gerberas adapt well to hydroponic growth as well, using rock wool or other types of inert media. Regardless of media, pot grown plants need steady fertility at all times, and they need pots that drain completely. Avoid pots that allow water to collect at the bottom. A simple dripper system, such as those used by hanging basket growers would be ideal for Gerbera production. Nutrients can be applied by fertigation allowing for steady establishment of a healthy crop.
Pot grown Gerberas have been shown to produce 25-30% more than those grown in soil, making this type of production worth the extra upfront investment.
Crates may also be considered, planting 2-3 plants per crate. Avoid putting crates on dirty floors or on top of natural soil to prevent root rot pathogens from taking hold.
Our Gerberas are shipped in spring, grown in a large plug that is ready for transplant on arrival. They should be maintained at temperatures in a range of 68/77 Fahreinheit night/day for their first 3-4 weeks. This allows for fast establishment of roots. After this establishment period, they can be allowed to cool to around 59F at night, and experience natural summer temperatures, with 64-77F being ideal.
Keep evenly moist at all times, but never allow them to stand in water. Maintain general even fertility. Gerberas grow steadily and flower continually so they need uniform access to water and nutrients. After establishment they will quickly initiate their first buds and then continue as long as warm days and long days continue.
Fall into Winter
With the decreasing light and temperature of autumn, Gerbera production will slow down a bit. If you can keep them warmer they will flower longer, and if you can maintain long day conditions they will also continue to flower well into autumn. Commercial growers in Holland heat and light their crops to mimic summer conditions all year long. Under these conditions Gerbera will produce for 2 years continually.
Gerberas never truly go dormant, but if you allow them cool dramatically in winter and don’t heat them, they will stop production for a time. This is totally fine for the plant. Water can be reduced significantly. Temperatures should be maintained above 35F. They are not hardy, and extended freezes will kill them. Your location will determine the heating needs of your Gerbera crop. As spring approaches you will see new growth emerge at which time you should increase feeding and watering. Buds will form quite early in spring and continue on all summer.
Year Round Production
As stated above if warm temperatures, long days, and sufficient light intensity can be maintained Gerberas can produce all year, and for 2 or more years continuously.
Well grown Gerberas can produce between 40 and 125 stems per plant per year when well grown.
Types of Gerberas
Harvest and Post Harvest
Gerberas should be harvested with blooms fully open. The color often changes from the time the flower first opens to when it is fully expanded, so don’t panic if they aren’t the expected color in bud. The pigments develop throughout maturation. Gerberas can be harvested by pulling them off of the plant, reducing the chance of pathogen transmission via cutting tools.
Stems should be cut in the morning when stems are most full of water and placed directly in a holding solution treated with a Gerbera tab. These tabs are essentially chlorine that help sterilize the water, reducing bacteria.
Your buckets must be sparkling clean. You cannot cut corners with Gerberas or they will wilt. Clean. Immaculate, okay?
If you have trouble with wilting, use a quick dip before placing in the holding solution with Gerbera tab. Gerbera can be held for 7-10 days in the cooler with a good lifespan afterwards. A commercial flower food should be offered to the retail customer to prolong the life of their purchase. Communicate cleanliness to your retail customers. They can last well more than 2 weeks if cleanliness is maintained.
Below you will find cultural documents provided by the breeders of our Gerberas. We have additional resources available for hydroponic culture if this is something you are considering. Simply inquire at firstname.lastname@example.org and we will gladly assist.