I am growing kale and this is the first year. It is the blue vates variety. My question is when and how to harvest. Days to maturity is 65 days (and it has been 65 days since I started the seeds indoors) but I don't think the plant has matured. I started with indoor seeds and slowly migrated them to 4 inch pots and last week to my raised bed. Any guidance on how and when to harvest? Should I wait for the plant to fully develop and then remove it in it's entirety? Should I be taking older leaves off and use them and if so how do I ensure that the new growth is not impacted.
It's best to harvest kale after it's been through a frost. Like most leafy vegetables you can harvest 20% of the leaves for eating, and let the remainder keep growing.
At my local farmers market, they sell kale leaves. So, they just harvest the outer leaves for sale. And then these leaves are about 2 feet in length, but a home grower might not get this size initially.
A good rule of thumb for Kale harvesting (and other plants) is to freely take any leaf that is losing a third of its sunlight to new growth.
If you're harvesting for personal use, don't worry about the "days to maturity" bit. Growing Kale to full maturity in the spring/summer takes a slightly pro touch, as it's vulnerable to a variety of pests.
Get the plant to 8" or taller with a healthy stalk, and freely take any leaves that are missing out on sunlight.
On your first harvest, the bottom leaves might be tough and taste bad - this is not uncommon. The rest should be tasty.
The sunlight rule of thumb, removing leaves that aren't getting as much light as they were, won't have any adverse effects on new growth.
To harvest, use a sharp tool and snip the leaf about 1/4" from the main stalk.
Remember to feed when necessary. Working compost into the soil around the plant every 1-2 months is a good idea as well, as it feeds the plant and the process aerates the soil. (For small/raised gardens, I recommend a garden tiller - combination tool with a 16"-18" handle, with a hoe on one side and fork on the other. The heavier head and longer handle easily give the fork enough force to work aggregate into the growing medium.)
Kale's soil should be always moist, but not wet. If the soil is wet, it needs some TLC, typically some worked-in compost, but an end-of-season overhaul works too.