🌿 Bring the Jungle Inside: Winter Survival Guide Part 2.Temperature. ❄️

Smokey: Too cold. We need more heaters so the plants feel comfortable.
Sunshine: I feel comfortable.
Smokey: You are not part of my plant collection, but I am glad you are comfortable.

🌡️ TEMPERATURE: THE TROPICAL DORMANCY LINE

In Part 1 (Winter Survival Guide: Temperature) we covered the foundation: light, placement, and acclimation. That is the survival layer.

Most tropicals stop growing below 70 to 75 F. They stay green, but their engine shuts down.

Below 70F:

• Water intake drops.
• Roots slow down.
• Fertilizing becomes risky.
• Root root becomes easy.

If you WANT your plants to grow in winter, you must take care of everything: Warmth, light, humidity, water. It all works together.

• Aim for 75 F with bright light. Water lightly. No fertilizer.
• Watch out for drafts. Cold windows. Door blasts. Garage entryways. Even one gust can trigger leaf drop.
• Vents are the opposite problem: hot, dry, dusty air. That gives you crispy edges and mites.
Root zone temperature matters just as much as room air. Your thermostat may say 72 F, but your pot on a tile floor may be sitting at 55 F. Fix this by elevating pots on boards or stands. Use Styrofoam. Never keep pots directly on cold tile o windowsill
• Extra winter heat: Space heaters are fine if used smartly. Do not blow hot air directly on plants. Keep heaters away from cords, trays, and water. Oil filled radiators are the safest option for plant rooms.
• Use a humidifier if you want growth or want to prevent spider mites. But do not blow mist directly onto leaves. Always place the unit lower than the plant canopy.
• Grouping helps. Put tropical plants close together to share humidity. Do not mix succulents with humidity lovers.
• Cats and dogs love to knock over lights and stands. Secure your fixtures. Trust us.
• Airflow: Light airflow is healthy. Direct fan blast is not. Still, dry corners invite mites.
• A mild night drop is OK. A big one below 55 F will stop growth completely.

A mandevilla thriving indoors with bright pink blooms and glossy green leaves.

☂️ PLACEMENT: MICROCLIMATES RULE EVERYTHING

Indoors is one big tradeoff: light but cold near windows, warm but dim away from them. The winning combo is a warm room with supplemental light.

Best zones to keep plants in winter:

• South or east windows with additional light
• Warm living spaces
• Bright bathrooms for natural humidity

Worst zones to keep plants in winter:

• Behind curtains
• Directly on windowsills
• Near heaters or vents
• Against cold exterior walls
• Dark corners without supplemental lighting

A vigorous indoor philodendron stretching across the window.

💨 ACCLIMATION

Moving a plant from outdoors to indoors is a shock. Light drops. Humidity drops. Airflow stops. Soil cools. Even healthy plants may drop some leaves for a few weeks. That is normal.

Before you bring them inside:

• Rinse foliage to remove dust and pests. We recommend Sunshine NoBug - and organic, safe solution.
• Check for ants.
• Trim weak branches.
• Treat soil if fungus gnats are present.

Try to bring plants inside before the first cold front, not after. If you are reading this too late, do the prep now and expect a little leaf drop.

If you nail light and temperature, winter becomes simple. In the next mail-list we will cover watering, fertilizer timing, humidity, and other indoor tricks that keep tropicals happy till spring. Stay tuned.

Cat Bob is inspecting his indoor garden around the tub with a bright skylight

✔️ WINTER INDOOR FAQ: TEMPERATURE AND PLACEMENT

Q: Why are leaves dropping only on the window side?
A: Cold glass. The room may be warm, but the glass surface can be much colder.

Q: Is a cold room OK for tropicals?
A: They may survive, but they will not grow below about 65F to 75F. When nights stay below 65F for a week, many plants enter dormancy.

Q: My room feels warm. Why is my plant still not growing?
A: Check the soil temperature. Pots on cold tile can be 10 to 20F colder than the air.

Q: Can plants sit directly on the floor?
A: Not on cold tile. Always elevate them on boards, stands, or trays.

Q: Is it OK to keep plants near a heater or vent?
A: No. Vents and heaters blast hot, dry air and cause crispy leaves and mites.

Q: My plant is dropping leaves after coming indoors. Why?
A: Normal acclimation to reduced light and humidity right after the move.

Q: Can I keep plants in a bright bathroom?
A: Yes. Bathrooms can have good humidity. Just keep pots off cold tile.

Q: Do I need a humidifier?
A: Not for survival. Yes if you want better growth and fewer pests like spider mites.

Q: Do I need a grow tent?
A: No. A bright LED plus a warm room is enough for winter holding.

Q: Should I fertilize in winter?
A: Not now. Winter fertilizer rules will be covered in the next mail-list.

Q: Should I water the same as in summer?
A: No. Indoor plants need much less water in winter. Watering rules also coming soon.

🛒 Shop Indoor Garden

📚 Learn more:

• Bring the Jungle Inside: Winter Survival Guide Part 1: Lighting
• SUNSHINE NoBug - Natural Plant Protector
• How to overwinter tropical plants indoors
• Feeding indoor plants
• Overwintering Adeniums outside of tropics

In Part 1 (Winter Survival Guide: Temperature) we covered the foundation: light, placement, and acclimation. That is the survival layer.

Part 2 (Winter Survival Guide: Temperature) is about what quietly ruins plants indoors in winter. Not overnight. Slowly.

Most winter losses come from good intentions and habits that worked fine outdoors or in summer, but fail indoors when growth slows.

Watering: Where Most Indoor Plants Die in Winter

If there is one winter skill that matters more than anything else, it is knowing when not to water.

In winter, light is weaker, temperatures are lower, roots stay cold longer, and growth slows or stops. Plants simply do not drink the way they do in summer.

How winter watering actually works

Do not water on a schedule. Winter does not care about your calendar.

Instead:

• Water thoroughly when you do water.
• Let excess drain out.
• Then wait longer than feels comfortable.

Before watering, test the soil with your finger. Water only when the top inch or so is dry.

If the soil below still feels cool and damp, do nothing. That is the hardest skill to learn.

Remember what we covered in Part 1: in winter, soil and roots stay cold much longer. Cold roots absorb water very slowly. Wet, cold soil is not helpful moisture. It is stress.

Waiting is often the correct move.

Common winter watering traps

• The soil surface looks dry, but the root ball is still wet.
• Pots near windows dry unevenly.
• Large pots stay wet for weeks.

Always check below the surface. If the pot feels cold and heavy, roots are not asking for water yet.

Signs you are watering too much

• Soil stays wet for many days.
• Pot feels heavy long after watering.
• Leaves yellow and soften.
• Fungus gnats appear.

As a rough guideline, most indoor tropicals need 25 to 50 percent less water than summer, sometimes even less in low light.

Always use room temperature water. Cold water shocks roots and slows recovery.

Humidity: Invisible Winter Stress

Winter indoor air is dry. Often far drier than people realize.

Heating systems pull moisture out of the air, and many homes sit at 20 to 30 percent humidity all winter. Most tropical plants prefer something closer to 50 to 60 percent.

Low humidity rarely kills plants outright. It weakens them first. That is why pests show up more often in winter. The plant is already stressed before insects arrive.

What low humidity looks like

• Brown or crispy leaf edges.
• Curling leaves.
• New leaves stuck while unfolding.
• Spider mites appearing suddenly.

What actually helps

• Group plants together.
• Use pebble trays.
• Run a room humidifier.
• Use bathrooms if light allows.

Humidity works best when plants are grouped. One isolated plant in dry air struggles far more than a group sharing moisture.

Misting leaves feels helpful, but it only raises humidity for minutes. It does not fix dry air.

Cleaning Leaves: More Important Than It Sounds

Winter light is already weak. Dust makes it worse.

Dusty leaves block light, clog stomata, and create hiding places for pests.

Wiping leaves is one of the simplest winter care steps, and one of the most ignored.

How to clean

• Soft cloth.
• Plain water.
• Mild soap if needed.

Gently wipe. No scrubbing. Every few weeks is enough.

Plants with fuzzy leaves, like African violets, should only be brushed gently with a dry brush.

Clean leaves also make problems easier to see. You will spot mites, scale, or damage early instead of discovering it weeks later.

Winter is not the season to be surprised.

Soil and Pots Behave Differently Indoors

Soil that works outdoors often behaves badly indoors. No wind, lower evaporation, and cooler roots mean the same soil stays wet far longer than expected.

In winter, roots care more about oxygen than water. Soil that stays wet pushes oxygen out, even if the plant looks fine above the soil line.

This is why rot often appears suddenly in late winter, not right after watering mistakes.

Pot size matters

Large pots dry slowly. Slow drying plus cool soil equals rot.

If a plant is barely growing, a very large pot is not doing it any favors.

About repotting

Winter is not the time to repot unless you must.

Only repot if:

• Roots are rotting.
• Pests are severe.
• The plant is clearly failing.

Repotting in winter slows recovery and often makes things worse.

Airflow: Quietly Important

Indoor winter air is still. Still air leads to mold, fungus, and spider mites.

Airflow is not about cooling plants. It is about breaking stagnant air layers that pests and fungus love.

A small fan on low, not blowing directly on plants, makes a big difference. Even gentle movement helps more than people expect.

Drainage and Mold: Boring but Critical

Never let pots sit in water.

Standing water causes root rot, fungus gnats, and mold smell. Always empty trays after watering.

Raise pots slightly so air can move underneath. It helps more than people expect.

If you smell sour soil or a musty odor, something is staying wet too long. That smell is an early warning, not a minor issue.

Fertilizer: Mostly Stop

This is where a lot of winter damage happens.

If a plant is not actively growing, fertilizer does not help. It hurts.

In winter, most indoor tropicals are in maintenance mode, not growth mode. Feeding during this time leads to salt buildup, root burn, and weak, floppy growth.

Green leaves do not mean the plant is growing. They often just mean the plant has not given up yet.

Growth shows up as new leaves, longer stems, or expanding roots. No growth means no feeding.

When light feeding is acceptable

Only if all of these are true:

• The plant is warm.
• Light is strong.
• You see real new growth.

Even then, feed lightly and less often than summer.

Spring will come. You do not need to force it.

Common Winter Care Mistakes

• Watering on a schedule.
• Misting instead of humidifying.
• Fertilizing to fix poor light.
• Ignoring cold windowsills.
• Placing pots on cold tile or stone.
• Repotting out of boredom.
• Letting trays stay wet.
• Assuming green leaves mean growth.
• Assuming winter leaf drop always means death.

Quick Winter FAQ

My soil stays wet forever.
Too little light, too cold, or pot too large. Water less.

Leaves are crispy but soil is wet.
Low humidity combined with overwatering.

Should I mist every day?
No. Fix the air, not the leaves.

Can I fertilize just a little?
Only if the plant is clearly growing.

Why do I suddenly have fungus gnats?
Wet soil indoors is the invitation.

My plant looks fine but has not grown in months. Is that bad?
No. Stability is success in winter.