Houseplants, or indoor plants, make a wonderful addition to any home and, what’s more, there are health benefits to having a few plants around.
But did you know that some houseplants can be put outside during summer and that some will actually benefit from a little summer vacation?
What is an indoor plant?
Houseplants, or indoor plants, are usually plants that come from tropical or arid climates and couldn’t survive a winter in a temperate or continental one. Typically, these will be plants that come from US Hardiness zones 9 and above.
In this article, by indoor plants I will be talking about what most people call houseplants and whose primary residence is your home.
There are, of course, other types of indoor plants. Some, such as tuberous begonias, may spend much of the year in a glasshouse, while others may only need bringing inside for the winter.
This includes things like border favorites cannas and dahlias.
Why should you move your houseplants outside?
There is nothing like fresh air and fresh rainwater to perk up a tired-looking plant. However good the conditions inside your home it will be unlikely that you can replicate the ideal outdoor climate.
Homes tend to be drier than many plants would like and tapwater often contains impurities or is harder than rainwater.
You will also notice that houseplants, like everything else in your home, get dusty and a summer rain shower is just the thing to wash that grime off and get those leaves sparkling again. Not only will this make them look better but they will also be able to photosynthesize better to produce their own food.
Another key factor is that houseplants can be used to produce a dazzling and lush summer display on a scale that it would be harder to achieve indoors.
Say you have as many as 30 houseplants in different rooms inside your home, you could group them together outside to produce a breath-taking summer performance. You are also likely to spend more of your time outside in the summer months so are around to make the most of them.
How cold is too cold for plants to be outside?
Obviously, houseplants can’t stay outside in all weathers otherwise they probably wouldn’t be houseplants!
As most of the popular houseplants come from warmer climes, many of them won’t survive outside all year round.
Precisely when to move plants outside depends, to a degree, on where you live and what the plant is.
As a general rule, the months of June, July, and August are probably the best ones – well after the first frost and when the nights have stooped getting cold, but back inside before fall begins.
For the exact temperatures for each plant you will need to consult a plant care guide. Those in hardiness zone 9 will tolerate a very light frost, while those in the higher zones of 12 and 13, where many houseplants are, need at least 55°F to thrive.
How long can I leave my plants outside?
As I say above, the summer months are the best and most plants will want bringing in at the end of August or into September. Furthermore, when you move them outside somewhere around mid-June it is not a good idea to do so all at once.
To begin with, try moving them out for a few weeks at the warmest parts of the day to get them used to the change in temperature. As this probably won’t be too much different to the temperature in your home in June it shouldn’t take too long!
The nights, though, may still be cool in early summer so bring them inside before dusk, perhaps until you get into July. Just as you would harden off your bedding plants before planting out do the same for your houseplants!
Should I put my indoor plants out in the rain?
Yes. For most plants. There are, however, some that are best kept inside. These include plants such as African violets or moth orchids and there are others so be sure to do a little research.
It’s also best to keep a particularly careful eye on them for the first few days so that if they show any signs of distress you can whisk them straight back indoors.
If a particularly harsh summer storm is forecast it would also be wise to bring them back inside. After all, who likes 60mph winds and almost horizontal rain!
If you are unfortunate enough to have a particularly wet summer, then some plants such as cacti and succulents will not enjoy it at all so either bring them back indoors or put them under some sort of shelter.
As always, keep an eye on the compost. Make sure it doesn’t become too wet, and water if it becomes too dry. Best not to stand pots in saucers either as that may mean plants sitting in rainwater. And make sure pots have drainage holes!
Where should I put my plants?
As with a lot of things it is all about location. If a plant likes to be placed well away from direct sunlight when it is indoors then don’t put it on a hot south-facing patio outside.
For example, a fern-like plant will soon get scorched if it is exposed to too much sun. Similarly, don’t put a group of cacti in a dark and damp part of the garden as they may just sit and sulk or, even worse, rot.
Also, consider access to water. You probably don’t want to scatter your plants around too much, particularly if you have a large garden, as it will make watering rather tiring!
It is perhaps better to place them in groups of similar plants and near to a water source such as the outside faucet or preferably a water butt.
Should I repot my plants?
It is likely that plants will grow most in the summer months and even more if moved outside so consider repotting them into a slightly larger container, especially if their roots are beginning to fill their pot.
Again, this depends on the type of plant you have as some like to be potbound.
Plants may also benefit from the freshening up of the compost that a repot provides. This leads on to feeding plants that are moved outside.
Most houseplants, with the possible exception of cacti, will benefit from a balanced liquid feed once a month in the growing season whether they are moved outside or not.
If they are outside, and if they do grow more, then you could move this to once a fortnight. Flowering plants may benefit from a high-potash fertilizer such as tomato feed.
What about pests?
If anything, being outside will help to get rid of many common indoor pests such as scale insects and spider mites. Certain pests, however, may be more of an issue for plants outside.
Slugs, for example, may take a liking to those plants with fleshy, green, appetizing leaves so keep an eye out for the sudden appearance of holes in the leaves.
It’s also a good idea to check pots before you bring them back indoors to check there’s nothing problematic lurking on top of the compost or clinging to the base of the pot.
To sum up…
When all is said and done it is generally a good idea to put your houseplants outside for at least a couple of months in summer.
However, this does depend on the type of plant you have and where in the world you live.
On the whole, avoid temperatures below 50°F, heavy rain or wind, or full sun or full shade.
Also, acclimatize plants to being outside gradually by bringing them in at nights for the first couple of weeks and make sure to get the watering right.
Plants will probably dry out quicker outside but there is also the risk of waterlogging if you get a lot of summer rain.