There's an important book titled "The Primeval Code" -- only available in German -- which offers a potential partial explanation for this observation ...
In laboratory experiments the researchers there Dr. Guido Ebner and Heinz Schürch exposed cereal seeds and fish eggs to an "electrostatic field" – in other words, to a high voltage field, in which no current flows.
Unexpectedly primeval organisms grew out of these seeds and eggs: a fern that no botanist was able to identify; primeval corn with up to twelve ears per stalk; wheat that was ready to be harvested in just four to six weeks. And giant trout, extinct in Europe for 130 years, with so-called salmon hooks. It was as if these organisms accessed their own genetic memories on command in the electric field, a phenomenon, which the English biochemist, Rupert Sheldrake, for instance believes is possible.
The Swiss pharmaceutical group patented the process – and then stopped the research in 1992. Why? Because "primeval cereals" generated by an electric field, in contrast to modern strains of seeds, require hardly any fertilisers or pesticides – i.e. crop protection agents, sold as priority products by Ciba at that time. The discovery was soon forgotten, without the global scientific community taking any notice.
In collaboration with the researchers involved – or rather their sons, in this book, the author has for the first time now disclosed in detail how the principle of this revolutionary bio-experiment works. Previously unpublished research reports, 64 exclusive photos, English-language patent specifications and interviews document the "Primeval Code" in all its aspects.
There are people experimenting with this already. The experimental apparatus is apparently simple (see paper), and there are apparently particular values for the field which work better than others.
Whether or not it is the same thing -- perhaps not (?) -- there are even cannabis seed companies who are experimenting with electricity on their mother plants ...
To increase your rate of success, TH Seeds used their groundbreaking Teslaponics to propagate Electric Lemon G Seeds. In simple terms, they shot jolts of electricity through the mothers to create very special regular seeds - they're not feminized, but the females outnumber the males by a higher rate than any other standard bean.
There is one fundamental reason why this research remains under the radar, aside from the point about business models made above: It's not generally thought that electric fields or cosmic rays should play any role as a signal that plants should actually care about. That's based upon the scientific worldview known as uniformitarianism -- that we can basically decode what happened in the past by looking at what is happening today in the present.
Uniformitarianism used to be a topic for debate back during the Velikovsky days, because what Velikovsky suggested were extreme transient electrical events which could basically confuse our ability to simply rewind time via dating techniques. What is curious is that there is no mention of this prior discussion when scientists observe radioactive decay rates here on Earth change in anticipation of extreme solar events, or when a sidereal (galactic) component to radioactive decay rates are commonly observed with Geiger counters. Both of these observations are invitations to consider that the plants know better than us about transient electrical events.
And we should know better actually -- for it is a fact that extreme electrical events do occasionally happen.
Even more disconcerting, telegraph systems worldwide went haywire. Spark discharges shocked telegraph operators and set the telegraph paper on fire. Even when telegraphers disconnected the batteries powering the lines, aurora-induced electric currents in the wires still allowed messages to be transmitted.
What we do not know is just how extreme the events can become, nor whether such extreme events might have an ability to permanently alter the Earth's electric field (etc).