How to Grow Asparagus Ferns Indoors or Outdoors - Dengarden - Home and Garden
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How to Grow Asparagus Ferns Indoors or Outdoors

Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.

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If you remember the seventies, then you remember fern bars. For everyone else, fern bars were upscale bars where upscale young people went to see and be seen. As the name implies, the main ornamental item were large ferns. Ferns were popular in that era as houseplants. The most popular of them was the asparagus fern.

Asparagus fern "fronds" are actually long stems with needle-like leaves.

Asparagus fern "fronds" are actually long stems with needle-like leaves.

What are Asparagus Ferns?

The asparagus fern (Asparagus aethiopicus) looks very much like an asparagus plant and like asparagus is a member of the lily family. It is not a true fern. Its "fronds" are actually long stems with needle-like leaves. Unlike true ferns which grow from stolons (runners), asparagus ferns grow from underground tubers. They also flower, something else you won't find on a true fern. The flowers produce berries that are first green, then turn red when ripe. Birds love them and help asparagus ferns spread by eating the berries and then excreting the indigestible seeds, usually far away from the original plant. Each berry contains 1 to 3 seeds.

The berries are not edible for humans. If eaten, they can cause vomiting, diarrhea and abdominal pain. The plants are toxic for dogs and cats so you might want to either not grow them or hang them high enough that your pets can't reach them.

Are Asparagus Ferns the Same as Foxtail Ferns?

Asparagus ferns are nicknamed foxtail ferns. However, that causes confusion because the foxtail fern (Asparagus densiflorus), although related, is a different species and looks very different. It grows upright rather than sprawling. Its branches look like foxtails, hence its name. Asparagus ferns look like asparagus.

Asparagus ferns produce flowers.  True ferns do not flower.

Asparagus ferns produce flowers. True ferns do not flower.

How to Grow Asparagus Fern Outdoors

Asparagus ferns are easy to grow. They are hardy in zones 9 through 11 where they can be grown outdoors year round. They are native to South Africa which is very dry so it is not surprising that they are drought tolerant. They work well in xeriscapes because they need so little water. Plant them in rich, well-drained soil and water sparingly. Fertilize monthly with a balanced fertilizer. Asparagus ferns grow best in dappled shade but can tolerate full sun. If grown in sun, the plants tend to be bushier and more compact rather than sprawling. In a shadier location, try planting them along the tops of walls where they can trail over the edge. You will need to divide your ferns every three years or so to prevent them from crowding out surrounding plants. The plants are not bothered by diseases or insects. They are so hardy that they are considered invasive weeds in Florida, Texas, Hawaii and New Zealand where they crowd out native plants.

The berries start out green, then turn red when they ripen.  Birds love them.

The berries start out green, then turn red when they ripen. Birds love them.

How to Grow Asparagus Fern Indoors

North of zone 9, asparagus ferns should be grown in containers and brought indoors during the winter. Use regular potting mix in the containers and place them in a semi-shady area outdoors. Indoors, they prefer indirect light or a north facing window. Fertilize your containers weekly with a weak fertilizer. Water regularly because containers dry out quickly. Bring your ferns indoors before the first frost in the fall. Keep them indoors until all danger of frost has past in the spring. Make sure that the room they are in is not too warm. Asparagus ferns prefer cooler temperatures. The room should be between 55°F and 70°F. They like being pot bound but you will have to divide them every two years because the mass of tubers will fill the container and prevent proper drainage. These ferns prefer to be dry, so if the soil in which they are planted doesn't drain properly, they will literally drown. When dividing your plants, replant each clump of tubers in the same size container that they were in previously so that they can "grow into" them, rather than in a smaller container which they will quickly outgrow.

You will need to divide your plants to prevent the tubers from filling the pot and preventing water from draining out.

You will need to divide your plants to prevent the tubers from filling the pot and preventing water from draining out.

How to Grow Asparagus Ferns From Seed

Asparagus ferns are easy to grow from seed. The seeds do require a bit of preparation. The seed coat is very hard so that it will survive its trip through birds' digestive tract. You will need to soften it before planting.

Harvest the berries when they are red and ripe. Remove the fleshy part of the berry, leaving just the seed or seeds. Knick the seeds with a knife or rub them with sandpaper. Then soak the seeds for at least 24 hours.

Now your seeds are ready to be planted. Use the same soil you use for growing them in containers. Plant the seeds 1/4 inch deep. Gently mist the soil until it is moist and then cover with plastic wrap to keep it moist.

Germination should occur in 3 to 4 weeks. When they develop their true leaves, they are ready for new homes. You can transplant your seedlings into containers or plant them outdoors after all danger of frost has passed.

Other than in xeriscapes, you don't see asparagus ferns much since their heyday in the seventies which is a shame because they are so easy to grow and make gorgeous houseplants. No one, I'm sure, misses fern bars.

Questions & Answers

Question: I’ve had my asparagus fern for several years, if not a decade. I have yet to see it bloom though. Why would it not be? It’s healthy and huge, but never once a bloom.

Answer: You don't indicate whether you are growing your plants indoors or outdoors, so I will make a few suggestions for both situations.

If you are growing your plant outdoors: it may be getting too much sun. Transplant to a shadier area. Are you fertilizing? Plants grown outdoors need to be fertilized monthly. When was the last time you divided your plant? It should be divided every two years.

If you are growing your plant indoors: it may be getting too much sun. Move to a north-facing window. Are you fertilizing? Plants grown in containers need to be fertilized every two weeks. How cool is the room you are growing it in? Asparagus ferns prefer cool temperatures. Move to a room that is 55F to 70F. When was the last time you divided your plant? It should be divided every two years.

© 2014 Caren White

Comments

Caren White (author) on August 07, 2020:

Sounds like it needs water. Asparagus ferns are drought tolerant which means that they like to be on the dry side but do need water occasionally. Las Vegas is located in a desert. Asparagus ferns do not grow in deserts because there is not enough rainfall. You will need to water your asparagus ferns to keep them alive.

Jo Ann on August 06, 2020:

I live in Vegas my fern is not in direct sun it gets a little sun in the morning Why does it ha ve dry dead areas??

Caren White (author) on June 18, 2019:

Sorry, but asparagus ferns are tropical plants. They will only grow year round in zones 9 through 11. In zones 5 and 6 they need to be brought indoors in the winter.

Jaydonone on June 17, 2019:

Will Asparagus Ferns survive winters in zone 5 or 6?

Caren White (author) on December 21, 2014:

Pawpaw, glad you found it useful. Thank you for reading and commenting.

Jim from Kansas on December 21, 2014:

I found this to be very useful, because we have one that is not doing so well. I wasn't aware of the cooler temperature requirement. That might explain it.