Tip 1: Good planting material allows for year-round yields
The most important ingredient to a successful indoor strawberry crop is perhaps the planting material. A growing strategy based on June bearing genetics does have its advantages but is only possible if good quality planting material is available all year round. We therefore chose to work with ever bearing varieties where however plant balance becomes much more of an issue. In our last round of experiments, we proved that harvests can be maintained for a full year! Establishing a sufficiently lush leaf canopy allows to maximally intercept light and can be achieved through vegetative triggers. After establishing that volume, new generations of leaves will much easier stretch to sufficient length.
Tip 2: Maintaining a good moisture deficit
Strawberries are true divas when it comes to climate. Strawberries, especially when mature, show high transpiration rates. To guarantee good leaf longevity, to prevent powdery mildew and to allow new generations of leaves to grow, a substantial moisture deficit needs to be maintained next to maintaining a good plant balance. A good moisture deficit has proven to be one of the most important prerequisites for achieving long cropping cycles.
Tip 3: Pollination and biological pest control
Pollination is key to achieving properly shaped fruits. Despite that our bumblebees must orient themselves in a dichromatic rather than a trichromatic world that they are used to, they appear to be perfectly able to navigate in indoor environments. In the absence of a natural sunrise / sunset we use automatic hive shutters to allow all the bumblebees to return to the hive before the lights are switched off.
Besides plants and bumblebees also pests feel well at ease in an indoor environment. Fresh plants from outside typically come with lice, thrips and spider mites. These hardy critters have caused more harm and heartache than we had ever imagined at the start of this journey. If left unchecked, these can ruin an entire crop but preventatively applied predatory mites and parasitic wasps prove to be well able to keep everything in check without needing to revert to chemical controls.
Looking ahead: it is about the economy
To make indoor grown strawberries a viable business case, a couple of steps still need to be taken. Most importantly, yields have to improve. And the good news is, there are sufficient ways this can be achieved. Our latest development for the Philips GreenPower LED production module with a standard beam achieves higher light intensities that are spread across a narrower surface area due to the lack of lenses. This makes the grow light ideally suited for row crops like strawberries where uniformity is much less important, and it also helps achieve a better light use efficiency. Lastly, upcoming experiments will focus on finding more optimal planting densities to make the business case realistic.