Hello! We're sorry that we haven't been clearer with this information.
Plants will grow in a certain way depending on what spectrum they are receiving. This is called photomorphogenesis. When plants receive a dominant red light, they will grow tall. When plants receive a dominant blue light, they grow more compact and with a shorter distance between nodes (branches).
Some growers prefer to use a dominant blue light during the seedling and vegetative phase to keep plants more compact and focusing on foliar growth rather than stem elongation.
What is more important than spectral quality, is intensity. No matter what spectrum we are growing with, if the light intensity is lacking, plants will grow tall and stretchy either way as they are reaching for the light source. As I'm sure you know already, household lamps that are made for human use have the spectrum rated in kelvin. A high kelvin means it has a lot of blue (cold appearance) and a low kelvin means it has a lot of red (warm glow). Sunlight in the middle of the day is around 5000-6000k and if we compare that to a classic HPS bulb which is 2200k, that makes a very big difference. In theory, plants would become stretched and lanky, but since HPS puts out high intensities, it still grows well. Many professional growers today still use HPS and think it is a good lamp that produces good results, but plants will also grow well outdoors in sunlight that has a kelvin rating of over 5000k.
The take-home here is that spectrum matters, but light intensity is far more important. A high intensity 2200k/red light will produce shorter plants than a 5000k/blue spectrum that is not strong enough.
If the 2200k and 5000k spectrums are both the same intensity, the 5000k spectrum will produce a bit more compact plants with more foliage growth and shorter stem.
Our lamp is designed to put out a balanced spectrum with both buttons activated at the same time. This balanced spectrum can be used from seed to harvest, but some growers still want to use an extra blue spectrum in the first week(s), which is why we split the spectrum in half. Although, most growers (including us) use both buttons activated at all times.
Light intensity is regulated with distance and your plants will experience different intensities depending on what height you hang your lamp at. We've made detailed intensity maps (PPFD-maps) that also have some general recommendations for high-light plants.
Here's the spectrum report for out Z5 grow light with all three settings. It shows what spectrum it puts out when having the blue, the red, or both buttons activated:
I'm also attaching the PPFD map below. It shows how the Z5 perform at three different heights in a 3x3' reflective space:
We know light can be tricky to understand and that it's a lot of information to take in. If you share some more information about your plants and grow space, I can help you figure out what height to hang the lamp at for optimal intensity and coverage.