When I was giving a talk to the Ipswich Bromeliad Society recently, the subject of using Seasol & also of using soluble Calcium for bromeliads came up in discussion. This prompted me to research these topics & to reassess what we are doing in relation to them in our own nursery. I would like to share with you the information I have accessed about Seasol in this article. I will be writing a follow up article on Calcium.
WHAT IS SEASOL?
Seasol is a brand name for a 100% organic seaweed extract. It is made from two species of seaweed – Bull Kelp (Durvillaea potatorum) & Knotted Kelp (Ascophyllum nodosum) both of which are sustainably sourced. The Bull Kelp grows in the clean oceans around King Island & the west coast of Tasmania where it is collected from the shores of remote beaches. Knotted Kelp grows in shallow intertidal waters. The base of the plant is left intact so that the kelp re-grows.
Seaweed contains a complex mixture of biochemicals including hormones that regulate plant growth. An analysis conducted at the Australian National University scientifically identified hormones called cytokinins & auxins. Cytokinins are known to stimulate cell division & new shoot initiation & have a general effect on shoot growth. Auxins have wide ranging effects on plant growth particularly stimulating the formation of new roots.
Seasol is a plant tonic (conditioner) & is not by definition a fertiliser as it contains only very small amounts of nitrogen & phosphorus.
Nitrogen = .2% (Ammonia & Nitrate form)
Phosphorus = .58%
Potassium = up to 4.3%
Sodium = .9%
Plus many other natural compounds & almost every known trace element
The amount of Potassium is beneficial for bromeliads & the trace elements contribute to overall plant nutrition. Sodium will be discussed later in this article.
SUMMARY of BENEFITS of SEASOL (as listed by the producing company)
* Increases cell division thereby stimulating plant & root growth
· * Enhances cell ‘strength’ resulting in increased tolerance to heat, drought & frost conditions
· * The effects of dehydration can be reversed after a single foliar application
· * As Seasol contains so little nitrogen & phosphorus, it won’t interfere with other nutritional inputs & it can be used all year round
· * Optimised plant health reduces the incidence & severity of some pest & disease problems
· * The natural compounds in Seasol also help to increase nutrient uptake, so when fertilisers are applied , they are much more effective
WORD of CAUTION
I was advised by an experienced horticultural chemist that Seasol should not be used for bromeliads due to its high sodium content (.9%) & its high pH (10). High levels of sodium are known to be harmful to bromeliads with leaf tip die back usually one of the first symptoms. This problem can be experienced with high levels of sodium in the water supply.
We’ve used Seasol in our nursery for years without any signs of damage to the leaves.
I’ve also mainly heard of positive results from other brom growers. A few people have reported problems (one grower experienced damage to the centre of the plants using full strength dilution in water).
Another grower reported using a stronger dilution than recommended without any damage.
So I rang Seasol & spoke to their Marketing Agronomist. He said that they had not tested Seasol specifically on bromeliads. However they had never received any negative feedback from brom growers. He was of the opinion that the dilution of the concentrate in water for foliar application reduces the amount of sodium to a non harmful level. He also stated that the pH of leaf surfaces helps to neutralise the high pH.
This is an important issue – will the physical properties of soluble fertilisers remain stable if mixed with Seasol?
The same horticultural chemist as before says no & that Seasol must be applied separately from other fertilisers, insecticides & fungicides.
The Seasol Agronomist said that the main nutrient that causes problems is phosphorous & it is therefore best to avoid mixing Seasol with any phosphorous containing compound.
Seasol has been tested with several insecticides & fungicides & found to be compatible with quite a few. The insecticides commonly used for bromeliads weren’t on the list. The fungicide Mancozeb was listed as ok.
We have decided to apply Seasol separately.
DILUTION & APPLICATION
Recommended: 25mls per 9 litres of water every 2-4 weeks
The level of dissolved salts presents in the water supply also affects the dilution that should be used (tank water having the least).
We use ½ strength (12.5mls per 9 litres) as an extra precaution due to the high sodium level & apply every 4 weeks.
*Dilution & how often applied is a personal decision. Just be aware of the level of sodium & watch carefully for any damage.
*There are other seaweed products on the market which I haven’t researched. The benefits are probably similar, but the information above relates specifically to Seasol.
*Powerfeed is also made by the same company. It’s a fertiliser with a higher level of nitrogen than potassium (N12%: P 1.4%: K 7%)