Here in Florida where the climate is subtropical, the line between houseplants and outdoor plants is often a little blurred.  But just because we can grow some houseplants outdoors year-round doesn’t mean we should. Did you know many of our beloved indoor plants become a menace when they are planted in the landscape? Several common indoor plants are considered invasive when grown outdoors.

Let’s start with what “invasive” means

Invasive plants are nonnative species, meaning they do not naturally occur in the state.  Rather, they have been introduced either intentionally or unintentionally by human activities.  Not all nonnative plants are invasive, but some can outcompete native species, disrupt ecosystems, reduce biodiversity, and alter natural habitats, all characteristics which earn them that title. As a rule, invasive species cause economic or environmental harm or harm to human health.  The State of Florida spends tens of millions of dollars annually combating these troublesome plants in conservation areas.  And this doesn’t even include the broader economic burden invasive plants present in agricultural lands.

The UF/IFAS Assessment of Non-Native Plants in Florida’s Natural Areas seeks to get ahead of the invasion curve.  The department uses literature-based assessment tools to evaluate the invasion risk of non-native species that occur in the state, new species proposed for introduction, and novel agricultural and horticultural selections, hybrids, and cultivars. Many of our favorite houseplant species originated in tropical Asia, Africa, and Central and South America and have spread via the nursery trade. Several of them have made the list and therefore are not recommended to be planted outdoors. Let’s break down a few of the worst offenders that are nearly impossible to eradicate once they take root.

Common invasive house plants

Pothos – Epipremnum aureum

Golden pothos, a native of Southeast Asia is the quintessential starter houseplant because it is very easy growing and difficult to kill.  It can survive with a little bit of water and a lot of neglect.  But it is this easy-going nature which makes pothos and all its cultivars extremely bad actors in Florida’s outdoor environment. These sturdy vines can grow to be almost as big around as my wrist.  By using aerial roots they attach themselves to buildings, fences, and tree trunks.

When allowed to escape into a wild area such as a forest or park, these voracious vines can quickly envelop everything in sight.  Leaves growing across the ground stay small but once they make the leap from horizontal to vertical growth they get massive-growing up to 2-3′ long!

Pothos is one of the easiest houseplants to multiply, and stem propagation is the most common and reliable method. Pothos are in the Araceae (aroid) family. Many aroids are epiphytes which means they can survive with no soil.  What this means outdoors is that any little plant part that gets torn off can become a whole new plant-even if it is far from the ground. This feature makes them especially difficult to eradicate, especially when they are grown into trees too high to completely pull off.  A little piece left up in a tree can survive for many months and will produce new aerial roots that eventually grow down into the soil.

Arrowhead vine – Syngonium podophyllum

Much like pothos, this pretty little plant can thrive outdoors where it will morph into a mega problem as it scrambles across the ground and up trees. Native to South and Central America, the leaves of arrowhead take a whole new shape once vines begin to lengthen and grow upwards. This phenomenon makes it a little tricky to ID in nature for those unfamiliar with its growth habits.  A mature plant in the wild looks nothing like it did that day you saw it in the nursery in its harmless little hanging basket.  It too is an aroid and easily multiplies from a single stem fragment.

Spider Plant- Chlorophytum comosum

If you’ve cared for one of these long lived passalong plants you know how easy it is to snip off a pup and gift to a friend or neighbor. Well, when these African beauties are hung outside and the pups, also known as spiderettes, fall to the ground they quickly take root and begin to spread laterally, forming a dense mat.  These escapees can choke out other plants, and when allowed into natural areas or vacant properties can create a monoculture.  For that reason it is not recommended to grow spider plants outdoors.  Keep them indoors or inside a screened room where you can enjoy their beauty without the risk of them spreading.

Snake plant Sansevieria trifasciata

Snake plant, aka mother-in-law’s tongue or bowstring hemp also hails from Africa.  It spreads horizontally through thick underground roots, or rhizomes, that send up new shoots.  This allows the plant to form dense colonies over time.  Snake plant is best enjoyed in a pot inside a screen room or patio where no part of it can contact the ground rather than planted in the garden.

3