A summer outdoors can be the best thing that happens to a houseplant all year. Real daylight is many times brighter than the light near even a good window, the air moves, and warm nights push growth in a way a living room never will. Most of our houseplants are tropical or subtropical in origin, and a few months in the fresh air often leaves them fuller, greener and readier to flower. The catch is the move itself. Indoor plants have spent months in soft, still, filtered light, and going straight out into sun and wind is a shock that can scorch leaves in an afternoon. This guide covers the whole seasonal move: when it's warm enough, how to acclimate step by step, which plants love it, and how watering and pests change once they're outside.
Let Growli track the switch: When you move a plant outdoors in Growli, it recalculates watering reminders for the brighter, windier conditions — so you're prompted more often, tuned to the plant and its new spot, not a fixed schedule.
This is one of five guides in our spring-into-summer series. Start with the pillar, Spring houseplant care — the complete guide, for the full seasonal picture.
Is it warm enough yet? The night-temperature rule
The single number that decides everything is the nighttime low, not the daytime high. A gorgeous 75°F afternoon means nothing if the temperature drops to 42°F after dark. Most houseplants are tropical, and cold nights stress or damage them even when there's no frost.
The established guidance from US Extension services is to wait until nighttime temperatures stay consistently and reliably above 50°F (10°C) before moving houseplants outdoors — Iowa State University Extension puts the safe threshold at that 50°F mark. In much of the northern US that's late May into June; in the south it comes earlier. In the UK, the equivalent is to wait until well past your last frost date and until nights settle into double digits Celsius — typically late May or June depending on how far north you are. The Royal Horticultural Society's hardening off guidance is a good regional reference, and it's worth stressing their point: hardening off makes a plant sturdier, but it does not make a tender plant frost-hardy. If a late cold snap is forecast, bring plants back in.
A few practical rules on timing:
- Watch the ten-day forecast, not the calendar. One warm week in April is a trap. You want a run of mild nights with none dipping toward the low 40s°F (single-digit Celsius).
- Don't move flowering or fussy tropicals first. Give the season time to settle before committing your most tender plants.
- When in doubt, wait a week. There's no prize for being early, and a cold night undoes weeks of good growth.
For more on why your plants care so much about the low temperature, see our temperature guide.
Why you can't just set them out
It's tempting to carry everything out on the first warm day and be done. Don't. Three separate shocks are waiting outdoors, and a plant straight off the windowsill is braced for none of them.
- Sun scorch. This is the big one. Window glass filters a large share of the sun's intensity, so even a plant on a "bright" sill is living in shade by outdoor standards. Set it in direct sun and the leaves — which have thin, indoor-grown cuticles — bleach, brown and crisp within hours. It looks like sudden death but it's sunburn, and it hits sun-lovers too, not just shade plants.
- Wind. Indoor air is still. Outside, even a light breeze tugs at leaves, dries them out fast, and can snap soft new growth or topple a top-heavy pot. Wind is the quiet reason a hardened-off plant still struggles if its spot is exposed.
- Temperature swing. Indoors, the range from day to night might be a few degrees. Outdoors it can be twenty or more. That swing alone is a stressor until the plant adjusts.
Hardening off is simply giving the plant time to build its defences against all three. As the RHS notes, the process thickens and alters the plant's leaf structure — the leaves toughen up, the protective cuticle thickens, and stems strengthen against the wind. Rush it and you're asking indoor tissue to survive outdoor conditions it was never built for.
How to harden off houseplants: a 1–2 week plan
The whole method is one idea repeated: more exposure, a little at a time. US Extension guidance is to start a plant in full shade outdoors and then introduce more light over roughly 10 to 14 days; the RHS allows two to three weeks, and warmer, softer indoor plants need the longer end. Here's a schedule that works for most foliage houseplants.
| Stage | Where to put it | Sun & time outside |
|---|---|---|
| Days 1–3 | Deep, full shade — a north-facing wall, a covered porch, under a dense tree | No direct sun; a few hours, then back in at night if it's cool |
| Days 4–7 | Bright or dappled shade; edge of a tree canopy | An hour or two of gentle early-morning sun; leave out overnight once nights are mild |
| Days 8–14 | Its intended summer spot | Build up morning and late-afternoon sun daily toward its target level |
Working notes that make the difference:
- Start in the shade even for sun-lovers. A cactus or a succulent needs hardening off just as much as a fern — arguably more, because you'll be aiming for far more sun at the end. Everything begins in shade.
- Favour morning and late-day sun. The midday sun is fiercest; eastern (morning) or northern exposures, or the shifting shade under a tree, are the gentlest places to start. Build toward harsher midday exposure last, and only for plants that truly want it.
- No deep shade available? Improvise. A layer of shade cloth, a garden umbrella or the shaded side of the house all work for the first few days.
- Watch the leaves, not the schedule. Pale, bleached or browning patches mean you've moved too fast — pull the plant back into shade for a few days and slow down. The days above are a guide, not a rule.
- Bring tender types in on cold nights during the first week if the temperature dips, until nights are reliably warm.
Because acclimation runs on outdoor light, it pairs naturally with the spring routine of easing plants back into stronger light indoors — see how to wake houseplants up in spring and our light guide for reading light levels.
Which plants love a summer outside — and which to leave in
Most houseplants enjoy a summer holiday, but the payoff varies, and a handful are better left on the windowsill.
Great candidates for going out:
- Sun-hungry plants that sulk indoors — cacti, most succulents, and citrus. They'll colour up, firm up and often flower with real sun (hardened off carefully to a bright, sunny spot).
- Big tropical foliage — monstera, philodendron, rubber plants, weeping figs, dracaenas, birds of paradise, palms. Warmth and bright shade suit them and they put on strong growth.
- Ferns and calatheas — happy in a shady, sheltered, humid corner. Keep them out of any direct sun and out of the wind; a shaded patio or a spot under trees is ideal.
- Flowering tropicals — hibiscus, bougainvillea and jasmine often bloom far better with a summer outdoors.
Better left inside:
- Fussy divas that hate change. Fiddle-leaf figs in particular drop leaves at the slightest disruption; many people find the move-and-move-back stress isn't worth it.
- Plants doing perfectly well indoors. If it's thriving, moving it is optional. There's no obligation.
- Anything you'd struggle to acclimate and re-inspect. If you can't give it two weeks of graduated shade or check it for pests in autumn, it may be simpler to keep it in.
A note on timing the move alongside repotting: if a plant is due for fresh soil, the warm months are the right season for it, but do the repot before or right at the start of hardening off so it settles while conditions are gentle — don't stack a repot onto a plant that's already coping with new sun and wind. For the mechanics, see when to repot houseplants and our step-by-step on how to repot a plant; if you're not sure it needs it, check the signs of a root-bound plant.
Watering and feeding change outdoors
The environment that dried a pot in a week indoors can dry the same pot in a day outside. Between real sun, moving air and higher temperatures, evaporation goes up sharply, and the number-one adjustment is to water more often — Extension guidance is simply to check soil moisture frequently and water thoroughly whenever the soil is dry to the touch.
- Check daily in a heatwave. A small pot in sun and wind can go from moist to bone dry between mornings. Feel the soil rather than guessing.
- Water in the morning so foliage dries through the day, and water thoroughly until it runs from the drainage holes.
- Mind the rain — both ways. A downpour can waterlog a pot that isn't draining freely, so make sure every pot has drainage holes and never sits in a saucer of standing water outside. Equally, a plant tucked under eaves may get no rain at all and still need you.
- Terracotta and small pots dry fastest; group them or move them into more shade if you can't keep up.
Feeding also ramps up. Outdoors in strong light and warmth, plants are actively growing and can use the nutrients — the reverse of the winter rule. A balanced, water-soluble fertiliser at half strength every week or two, or a slow-release feed applied at the start of the season, keeps pace with summer growth. Ease off again as the days shorten in late summer.
Pests: the outdoor trade-off
Outdoors, your plants rejoin the food chain. The upside is that beneficial insects often keep pests in check for free; the downside is that aphids, spider mites, scale, mealybugs and slugs can all move in, and soil-dwellers like fungus gnats, ants and sowbugs may set up home in the pot. This is normal — but it changes what you do at the end of the season.
The rule that saves you a winter of infestations: inspect and clean every plant before it comes back inside. Extension services recommend a thorough check and a rinse of the foliage while still outdoors, letting leaves dry before the plant crosses the threshold. Check leaf undersides and stems, hose off what you find, and consider isolating returning plants away from your indoor collection for three to four weeks so any hitchhikers show themselves before they spread. It's far easier to deal with a pest on the patio than loose in the house.
Bringing them back inside
The return trip is the reverse of the threshold that sent them out: bring plants in before nights drop consistently toward 50°F (10°C) again, and well ahead of any frost. In much of the northern US that's September; in the UK, plan for September into October depending on region. Don't wait for the first cold night — a single chilly evening can damage a tender tropical.
A gentle re-entry matters too. A plant that's grown lush in bright outdoor light will find your indoor light dim by comparison, so expect some leaf drop as it readjusts, and try to give it your brightest spot for the transition. Avoid heavy pruning during the move — save any real cutting-back for its proper season, covered in pruning houseplants in spring. For the wider set of autumn and cold-weather adjustments, our houseplant winter care guide picks up where the summer holiday ends.
Your summer-move checklist
- Wait for the weather. Nights reliably above 50°F (10°C), past your last frost, with no cold snap in the ten-day forecast.
- Do any repotting first, at the start, so the plant settles before the sun and wind arrive.
- Days 1–3: full shade. Set everything — even sun-lovers — in deep shade outdoors.
- Days 4–14: add light slowly. A little morning sun, building daily toward each plant's target. Watch for bleaching and slow down if you see it.
- Water more, feed more. Check soil daily in heat; water when dry, feed dilute through summer.
- Inspect before autumn. Rinse and check every plant for pests, then bring them in before nights cool toward 50°F — well before frost.
Fine-tuning the move for a specific plant? Browse our plant-care guides by species for the ones that want full sun versus the ones that scorch in an afternoon.
Related articles
- Spring houseplant care — the complete guide — the seasonal pillar that ties the cluster together
- How to wake houseplants up in spring — easing plants back into light and growth
- When to repot houseplants — best timing — do it before the move, not during
- Pruning houseplants in spring — when and how — the right season for cutting back
- Houseplant winter care — the complete guide — where the summer holiday ends
- Plant-care guides by species — which plants want full sun and which scorch
Reviewed and updated by the Growli editorial team. For questions about anything here, open Growli and ask — or email hello@getgrowli.app.
Frequently asked questions
When is it warm enough to put houseplants outside?
Wait until nighttime temperatures stay consistently and reliably above 50°F (10°C), and until you are safely past your last frost date. The daytime high does not matter as much as the overnight low, because most houseplants are tropical and cold nights stress them even without a frost. In the northern US and much of the UK this usually means late May or June. Watch the ten-day forecast rather than the calendar, and if a cold snap is coming, wait.
Can I put houseplants outside straight away?
No. Indoor plants have thin, soft leaves grown in filtered light and still air, so moving them straight into sun and wind causes scorch and shock, sometimes within hours. You need to harden them off gradually. Start every plant, even sun-lovers, in full shade outdoors, then add a little more light each day over one to two weeks so the leaves toughen and the plant adjusts to the temperature swings and breeze.
How do I harden off houseplants?
Move the plant from indoors to a full-shade spot outside for the first few days, then increase its light exposure gradually over 10 to 14 days until it reaches its intended summer position. Favour gentle morning sun and build toward stronger midday exposure last, only for plants that want it. Watch the leaves: pale or browning patches mean you moved too fast, so pull it back into shade and slow down. Bring tender plants in on cold nights during the first week.
Why did my houseplant get sunburned outside?
Window glass filters much of the sun's intensity, so even a plant on a bright windowsill is living in shade by outdoor standards. Set straight into direct sun, its thin indoor-grown leaves bleach, brown and crisp — that is sunburn, and it happens fast. It affects sun-loving plants too, not just shade plants. The fix is hardening off: begin in full shade and increase sun slowly so the leaves build a thicker protective layer before they face direct light.
How often should I water houseplants outdoors in summer?
More often than indoors, because sun, warmth and wind dry the soil much faster. Check the soil moisture frequently and water thoroughly whenever the top feels dry to the touch. In a heatwave, a small or terracotta pot in sun and wind may need water daily. Water in the morning, until it runs from the drainage holes, and never leave a pot standing in a saucer of water outside. Feel the soil rather than following a fixed schedule.
Which plants should not go outside for summer?
Leave fussy plants that hate any change, such as fiddle-leaf figs, which tend to drop leaves at the slightest disruption. Also skip the move for anything already thriving indoors, since there is no obligation to move a happy plant, and for plants you cannot commit to acclimating over two weeks or inspecting for pests before autumn. Everything else, from cacti and succulents to big tropical foliage, ferns and flowering tropicals, generally benefits from a careful summer outside.
How do I bring houseplants back inside without bringing pests?
Inspect every plant thoroughly before it comes indoors, checking leaf undersides and stems for aphids, mites, scale and mealybugs, and the soil for gnats or slugs. Rinse the foliage while the plant is still outside and let it dry. It helps to isolate returning plants away from your other houseplants for three to four weeks so any hitchhikers reveal themselves before they can spread. Bring plants in before nights cool toward 50°F, and well before frost.