I have a problem with over-harvesting the herbs growing on my windowsill. When my rosemary starts branching out, I can't help myself from cutting it to bits. What's a good way to cut herbs to encourage growth and not kill your plants?
-Andrea from Brooklyn, NY
First of all, congratulations on growing herbs. You are one step closer to FarmAndrea... Famdrea?
I had a former roommate who would cut every Rosemary sprig off of her plant and then wonder why it wouldn't grow anymore. First rule: Your herbs need to absorb sunlight through their leaves in order to grow. No leaves means no sun is being absorbed, which is just as bad as putting the plant in a dark cabinet.
Ok, good, now that we have that cleared away, let's talk specifics of harvesting some of the most popular container herbs:
Rosemary will continue to get big and bushy if you are strategic about the way you harvest it. Cut Rosemary at the stem so that you are cutting off a full sprig and the stems will regenerate. To slow down it's growth, pluck the Rosemary needles off of the intact stem to use one by one: the Rosemary won't regrow until the entire stem is cut off. But don't pluck off more than 20% of the Rosemary needles... that won't just slow down the growth, it will probably kill the plant.
If you do accidentally over-harvest your Rosemary, you can create new plants by a process called layering. When you have one long stem of rosemary, pull the needles off of the top third of the stem (but keep some at the bottom for that sun absorption we talked about). Bend the stem into a U-shape and stick the tip of the naked stem into the soil. If you keep the soil moist, new roots should appear from this stem! You can cut the U-shape after a few weeks and you'll have a second plant growing in the pot.
Rosemary can be used fresh, dried, or frozen in storage immediately after harvesting. And if you're growing it indoors, don't forget to mist the leaves of the plant in dry winter months.
Basil will produce a super crapload of leaves if correctly harvested and pruned (yes, "super crapload" is a technical measurement). You'll notice that basil leaves grow in sets of two across from each other. New leaves grow in the upside-down armpits of mature leaves, so you'll often see tiny babies beginning to sprout right above fully formed leaves. Always cut Basil off at the stem directly above a set of leaves instead of picking off single leaves. If you cut the stem right above tiny baby armpit leaves, those little dudes will form into new branches because they think that they're the plant's last shot at growth. Voila, millions of new Basil branches begin each time you harvest!
If you're not going to use the basil, you should still harvest it so it continues to grow. You can cut off long stems of leaves and put them in water to keep them alive, using the leaves from it over time. If left long enough, these cuttings will grow roots in the water, and you can plant the cuttings as new plants!
Basil will eventually sprout cute little flowers, but if you want to keep using the leaves of the plant, you'll need to cut these off. Once the flowers start to form, the leaves get the signal that their job of absorbing sunlight for the plant is done because the flowers (and pollen and seeds) are on their way. The leaves will change flavor and the plant will complete it's life cycle and die. So, just trim the flowers and keep harvesting as usual.
Basil has the most flavor by far when used fresh and should only be used this way. If you use dried Basil, you are letting the terrorists win, abandoning sick puppies, and forcing our children to turn to drugs.
Mint is pretty invasive and will take over your garden, so it's a good plant to keep in a pot. There are about 25 types of Mint, but the most popular mint grown as a garden herb is Spearmint. You probably shouldn't grow Pennyroyal Mint... it is poisonous, has been used to induce abortion, and will leave you singing that Nirvana song over and over. So, you know. Stick with the Spearmint.
Unlike most other herbs, mint can be picked at random and will still continue to grow. You can pull off leaves as needed or cut an entire stem full. Like Basil, the flowers should be pruned off to encourage continual growth of the leaves throughout the season. Prune Mint constantly to keep it healthy, and cut off any damaged or brown leaves. It's definitely the easiest herb to grow, so it's good for beginners!
Mint can be used fresh (muddled in cocktails!), but it also retains it's flavor when dried (sprinkled in sauces!).
Here's a quick note: the best way to dry cut herbs is to tie the stems together with some string and hang them upside down (the opposite direction from how the stem was growing naturally) in a cool, dry, dark place. Let them hang for a few weeks, and then store the dried herbs in an airtight container and use as needed. When I dry Rosemary, for example, I keep the stems intact in a container and remove the needles right before using. When I dry mint, I actually crumble the dried leaves into a container for storage and use it as mint "sprinkles" when I cook. If you dry Basil, well, you should probably just turn yourself into the authorities.
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