By Sally McCabe, Associate Director of Community Education at PHS 

After a long winter spent in the dry, dimly lit confines of our homes, houseplants are more than ready for a change of scenery. In Zone 7, once the threat of frost has safely passed (usually around Mother’s Day), it’s time to start thinking about when to put houseplants outside. 

This seasonal move is like “summer camp” for plants. Once they head outdoors, they often explode with new growth thanks to the Mid-Atlantic's humidity, brighter light, and natural air circulation. But the key thing to consider is not just moving plants outside, but how to do it without shocking them. 

When Can I Put My Plants Outside in Spring? 

In the Mid-Atlantic region (Zone 7), the general rule is: 

• Wait until after the last frost (typically mid-May or Mother’s Day)  
• Watch until nighttime temperatures are consistently above 50°F. This is a safer threshold for most houseplants.
• Then begin a gradual transition outdoors, but don’t rush it. A sudden move from a cozy windowsill to full sun is the plant equivalent of being dropped off at summer camp without warning. 

Coleus is my personal “indicator plant.” It tells me everything I need to know: too cold, too hot, too dry, or too buggy, and it reacts immediately. Dramatic, yes. Also, very useful. 

How to Prepare Plants Before Moving Them Outside

Start preparing about a month before your target date for moving plants outside. A little prep now makes a big difference later. 

• The Spring Haircut: Snip off yellowing leaves or winter scorch. For coleus and other plants that have gotten leggy, pinch back the tops now to encourage a stockier, fuller habit—or cut back hard and root the cuttings. 
• Begonia Care: Mine burst into bloom in February, stimulated by lengthening daylight hours, but are looking sad by now. Remove spent blooms or straggly stems to redirect energy into new outdoor growth. 
• Decide Which Plants Are Staying Indoors: Not every plant wants to go to “camp.” Some may be happier staying put, and that’s okay. 
• Pest Patrol: Winter is a safe harbor for mealybugs, aphids, and spider mites. Check the undersides of leaves and treat early with insecticidal soap. Hardening off gradually will also reduce stress and pest pressure once plants are outside. 
• Water Well: Make sure your plants are well-hydrated before moving outdoors. 
• The Soaking Method: For smaller pots, submerge the pot in a bucket of water mixed with worm compost tea to hydrate and feed simultaneously. 
• Feed Wisely: Skip heavy synthetic fertilizers early on. Use organic options like fish emulsion or seaweed at half strength until plants are established outside.

Preparing Your Outdoor Space for Houseplants

Before you put plants outside, take a moment to prep the space they’re moving into. 

• Assess the Outdoor Space: Light conditions may have changed over winter; double-check before placing plants. 
• Inventory Containers: Have larger pots ready if you plan to repot once plants are outside. 
• Check Pots and Containers: Look for root-bound plants or cracked trays. 
• Inspect Hoses: Make sure everything is working after winter storage.
• Harness the Power of Worms: Refresh the top layer of soil with compost or worm castings for an easy nutrient boost. 

How to Move Plants Outside Safely (Hardening Off Guide)

As you get closer to the final move for your plants, don't just throw them onto a sunny porch. The most common mistake is moving a plant directly from a dark corner to a sunny porch. Increase sun exposure gradually. Even sun-lovers need to be hardened off in deep shade for at least a week. 

• Dappled Light: Start by moving plants to a very shaded outdoor spot for just a few hours a day. 
• Sun Sensitivity: Remember that even sun-lovers like cactus can get "sunburned" if moved too quickly from a dim indoor corner to the "blowtorch" of direct midday sun. 

Sun, Shade, and the “Blowtorch Effect” 

Certain plant species have specific needs when it comes to how much sun they can tolerate when they are moved outdoors. Make sure to take a look at the list below! 

• Begonias: These are the queens of shade. Keep them in sheltered spots where they can enjoy the humidity without the midday heat wilting their succulent stems. 
• Coleus: For coleus, the lighter the foliage, the more sun they can tolerate, but they still prefer a break from the intense afternoon heat.
• Cactus and Cereus: While desert cactuses love the sun, the Night-blooming Cereus and Christmas/Thanksgiving Cactuses are actually epiphytes (tree-dwellers). They prefer dappled light. Too much direct "blowtorch" sun will turn their segments a stressed reddish-purple or burn them entirely. 

How to Care for Houseplants After Moving Them Outside

Once your houseplants are officially moved outside: 

• Water more frequently, sometimes daily in hot weather  
• Hanging baskets may need water twice a day during heat waves  
• Use heavier pots or sheltered locations for wind protection  
• Group plants by needs and use “indicator plants” like coleus to signal stress  

Outdoor conditions change quickly; sun, wind, and heat all increase plant demand dramatically. 

Final Takeaway: Timing Matters When Moving Houseplants Outside 

Moving houseplants outside is one of the best things you can do for them if you time it right and transition them gently. The real answer to when to put houseplants outside isn’t just “after Mother’s Day.” Make sure that it's:

• After frost danger has passed  
• After you’ve prepared them  
• After a slow hardening-off period  

Done well, your plants return indoors in the fall stronger, fuller, and noticeably happier for their time at summer camp. 

Just keep an eye on the forecast because in this region, a surprise cold snap is always part of the curriculum.