9 Herbs that want to take over your garden

I really love growing herbs. Nothing beats freshly harvested herbs to really perk up a homemade meal. I grow about 20 different herbs every year for both food and medicine. While some herbs have given me a really hard time getting them to grow (I'm looking at you white sage!) other herbs, have gotten completely out of hand in the garden.

My first out of control herb was dill. It was my first year with an unlimited sized garden and I was going to grow my own dill and learn to make pickles. It was also my first year with chickens and I had sadly underestimated their drive to get into my garden and take 2 bites out of everything they could find. 

Since the pickling cucumbers were a bust, I let the dill go to seed. Big mistake. Dill has popped up in my garden every year since.

A Calendula infestation followed closely behind the dill problem...though you can really never have enough calendula so that's not so bad. 

Shortly after Valerian started popping up in and out of my garden, as far away as my driveways edge! Since then there's been several invasive herbs including catnip, chamomile, chives and....well, here's the whole list!

  The most invasive garden herbs

Catnip:

Catnip seeds will fall off the plant and plant themselves absolutely anywhere! Even in the smallest of areas! Last year I thought it was brilliant to keep my catnip in a pot. That would keep it from spreading in the garden. I had it on my patio and I allowed it to go to seed, because I thought the seeds had nowhere to grow. 

This year I have catnip growing in every pot that was anywhere near it on the patio, and also in the seam of the concrete and all along the edges. See it growing under the table in that picture? That stuff is crazy!

Here is How to use catnip tea for you (not the cats!)

Calendula:

After Calendula blooms, the flower dries up and the seeds are formed. If the flower or seed heads aren't removed they will fall off and plant themselves for next year. I've been growing Calendula for 6 years and only planted it once.

Chamomile:

Every chamomile flower is jam packed with seeds. Therefore, every flower left on the plant can potentially turn into hundreds of plants. It's a challenge to get them all and trust me, every single one you miss will plant itself! 

Chamomile seeds are so light they will easily blow away on the wind, and you'll find them growing all through your lawn. Not that I know from experience or anything! Learn How to grow and harvest chamomile.

Chives:

Chive seeds are contained in the chive blossoms. If they are not plucked, they will dry up and droop over. When the flower heads become completely dry, the seeds drop off and will plant themselves. You'll have a ring of single chives pop up all around the original plant. 

While this might not seem like much, let this happen a few years and they've spread several feet across the garden bed! I suggest cutting the flowers off and making chive blossom butter.

Dill:

Dill is the first herb I planted exactly once, this one was 7 years ago. The stems get quite tall and when the flowers go to seed they tend to blow all over the garden.

Lemon Balm:

Once established in the garden, the clump of lemon balm will get larger and larger every year. It produces seeds much like catnip does and they also like to plant themselves wherever they land....though unlike catnip, they're not a fan of patio cracks! Luckily lemon balm is very useful medicinally.

Parsley:

Parsley has the same MO as dill except parsley is a biennial, so it only flowers every 2 years. The parsley flower stalk grows to about 4 feet tall, so the seeds are easily blown loose by the wind and dropped all over the garden. The following year you will have parsley growing everywhere the seed dropped! 

Learn the benefits of eating parsley every day!

Mint:

Pretty much anything in the mint family. Spearmint, chocolate mint, peppermint etc. I must mention that most members of the mint family will become quite invasive if left to their own devices. 

Mint, oregano, pennyroyal and even thyme will spread through underground runners and can quickly take over the garden. They can be hard to remove as small bits of roots left behind can grow into full plants. 

That is why I always plant mint in a container.

Valerian:

Valerian has beautiful, delicate white flowers on tall stems. Like most of the other herbs on this list, the seeds fall from the flower heads after they've died off. Since Valerian is so tall (about 6 feet!) the seeds will scatter in a pretty large area. 

Valerian seeds don't normally germinate very easily. However, when you look at the hundreds of seeds produced by a few blooms, it makes sense that some will grow! 

Learn how to grow and harvest Valerian root.

Preventing herbs from taking over the garden

With all of these herbs the best preventative is to deadhead them...remove the flowers before they go to seed. If you catch them in the window after they bloom and before they're dry they won't reseed themselves. 

This is easily done with dill, Valerian and chives. Calendula is a little more challenging because of the large quantities of flowers it produces. Chamomile is darn near impossible.

If catnip is harvested as soon as it flowers, the seeds should not be a problem at all. Towards the end of the growing season it's puts extra effort into flowering so you really have to stay on top of it or every single seed you miss will plant itself! 

Basil can self seed like catnip unless harvested regularly (though personally it hasn't for me) so it's a good idea to keep it trimmed or pinch off the flowers when they start to develop.

Other herbs with a reputation for reseeding themselves: fennel, sage, cilantro, sweet Annie, feverfew, borage, mullein, comfrey and tarragon. Rosemary tends to grow like crazy in southern states though sadly, that's not a problem up here in Pa!

If you mulch heavily or put down a weed barrier each year then reseeding won't be much of a problem for you. I tend to only mulch heavily directly under my plants so these herbs pop up all along the walkways and in the lawn! 

While that is sometimes a good thing since I never have to plant them, every year I end up selling dozens of plants and composting even more of them. Maybe I should open a farm stand?

For plants that spread through runners, the best bet is a raised planter. Metal is best for a pot, although wooden raised beds work well too. Stay away from ceramic or plastic pots if you plan on sinking them into the ground. They will weaken over the years and eventually the runners will break through.

If all else fails you could plant invasive herbs in a container garden to keep them, well...contained, just be careful because dropped seeds still might grow in in small cracks and crevices! 

Want more posts on herb gardening? Click here for my other posts on growing herbs.

~L

Related reading: These are the 11 Medicinal herbs the can be grown indoors which makes them much easier to control!

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