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How to prep your indoor plants for winter so they don't die

With winter well on the way, it's time to prep our precious indoor plants for the colder months to make sure they get through happy and thriving, not dead or barely surviving. I remember my first 'winter with plants' when I had enough of a collection of valuable plants to worry about them making it through. Following these tips, I would have had nothing to worry about. Okay. True. Less to worry about (I worry a lot).

 


'Winter is Coming' doesn't immediately conjure up pictures of dragons, wolves and White Walkers like it used to. But I'm going to milk that Game of Thrones reference just a bit longer. Because winter is coming. And for the plant addicted, winter can be a tad scary.


Summer is just SO easy. Root rot what? Often the biggest issue is just keeping up with watering the thirstiest chaps in the jungle, without going overboard and ending up with fungus gnats. Overwatering seems (almost) impossible.


Come winter, root rot becomes a serious reality and the #1 killer of houseplants over winter. Overwatering is SO easy to do in winter. And overwatering can mean a swift death sentence compared to underwatering. Plus our plants can fool us into overwatering them if we don't know better. 


But water's not the only winter worry. Here's what I do to get my indoor jungle prepped for winter, and what I've learned NOT to do as well, so they (and me too!), get through the colder months without the stress.

 

Aziz, more light!

(that reference is for you Fifth Element fans)


If you're lucky like me, and get lots of light at your place, winter is wonderful. Instead of paranoid opening and closing of curtains and blinds to make sure no-one gets cooked as the sun moves around the house, now you can chill. Although some do get their grow lights switched on to help them get through.


Winter sun - even direct - is weaker than our intense summer sun (at least in my part of the world). Some plants you would normally never dare place in the path of direct sun, can thrive over winter with a little sunbathing.


Great for a bit of sun stress (of the good kind), to colour up your plants too. Keep your Ficus Elastica Ruby red, and give your Tineke a soft blush. Keep Syngonium pink and Pink Bubbles from reverting. An absolute necessity for most of your String-of and Chain-of everything's to get them through winter. Not for colour, but for survival. My String of Pearls HAVE to move to the windowsill for hours of direct winter sun a day to get enough direct rays not to go bald and slowly die off over winter at my place.


Most of our indoor plants need more light over winter, so even if direct sun is a no go, move your jungle closer to sources of light or grab a grow light. Remember winter also means shorter days, so that means fewer daylight hours, so shift your plants in the best position to make the most of what they can get.


If you're worried it's still a bit low light to keep your jungle going, even with shifting them to new locations for winter, grab yourself a grow light for a few hours of extra light every day. For example, even one Sansi 24 watt in a floor lamp (or 2 of the Sansi 15 watt in desk lamps), work like magic to boost light levels.


Bye bye dust bunnies


With more daylight hours and much brighter light in summer, a light coating of dust isn't too bad. Enough light can get through for plants to get by. But come winter, those dusty leaves can cause health issues, and when dealing with less light and drier air, clean leaves that can breathe and photosynthesize become even more important.


Grab a soft, damp cloth (I use those awesome dusting gloves), chuck something on Netflix to binge watch, and get wiping. It's very therapeutic. I use the Plant Runner Neem Oil Leaf Shine for mine, but have heard a lemon juice and water mixture also works well.


The Plant Runner Leaf Shine isn't a silicon type of leaf shine that clogs your plant's pores or leaves behind a fake-looking glossy shine, so it's very safe, plus a little goes a long way. Some also use neem as a natural insect repellent to help keep pests away. Check first if your plant is oil-sensitive as oil-based products aren't for 100% of plants. I stay away from leaf shine products for all my furry-leafed friends too (they get a once-over with a soft toothbrush instead to get rid of dust).


If you're not in the mood for a leaf-by-leaf wet wipe, chuck everyone in the shower for a good rinse, or get a spray mister out and banish those dust bunnies. Remember even with a good shower rinse, dust can be pretty stubborn, so you will likely still need to wipe at least the newer leaves (who do a lot of the heavy lifting for photosynthesis).


Don't forget your windows

 

Speaking of cleaning, what are your windows looking like? Dust, dirt and mineral deposits can build up on glass, letting less light in to reach our precious plants. They might need a good spring clean too as part of your winter prep while you're in the cleaning mood (and if you feel like cleaning mine too, yes please, I never seem to be in this magical thing called 'cleaning mood').


dirty window



Warm and toasty


Most of the indoor plants we love come from climates that stay warm, bright and humid all year round, with a 12 month growing season. Put them in a typical NZ house over winter and they may be missing home pretty fast. 


If your place gets below about 10 to 15 degrees indoors on the regular over winter, consider an oil heater or similar in the room your plants are in, set to come on when the temperature drops, to help your plants get through winter. Mine gets set to 15 as some of my jungle are less tolerant of those overnight lows. In enclosed areas like an Ikea cabinet or terrarium, you can get your plants a plant heat mat as a much more affordable and effective way to heat a small area instead of an entire room. If you get the type with a controller you can set the minimum temperature and leave it on 24/7, or just get a basic one that maintains the temperature 10 degrees or so above the room temperature. Inkbird makes both types.


Plants who thrived on windowsills during summer usually need to be moved further away from the glass over winter nights as that can be one of the coldest places in a home. Also shift plants away from the path of cold drafts, and warm drafts too such as the path of air con units, and set back further than you might think away from heaters and fireplaces which can scorch delicate leaves. 


A dry cry for help


Beware some heat sources. Many dry the air. The trusty HRV, DVS, air conditioning, heat pumps and even your fireplace are all common culprits for this. Bad news for our humidity-loving indoor plants.


Weird as it sounds, another danger from dry air is root rot, also called dry rot. That's because our plants are fooling us. Dry tips, crispy edges, all signs point to thirst, right? But don't fall for it!


Check that soil. Go down as deep and close to the roots as you can. Get yourself one of the types of soil testers that check moisture down at root level (Sustee are awesome if your budget allows, otherwise GrowProbe are a simple more budget friendly solution too). A total winter water game changer to avoid root rot. 


Don't be surprised if you find the surface is dry but the rest of the soil plenty wet. Some signs that look like thirsty roots, are more likely a cry of attention trying to tell you humidity's too low. If you'd fallen for it and watered, you could easily lose your plant to root rot, when all they needed was humidity.


Used to high humidity all year-round in their natural climate, many indoor plants can really suffer over winter. Invest in a couple of humidifiers (those H2O portable cordless humidifiers are a game changer).


Misting and pebble trays barely make any difference, if at all, over winter (or summer for that matter). Shifting plants into the bathroom? Same problem. Barely enough humidity for long enough to make much difference. Plus most bathrooms are designed to dry fast, and stay cooler and drier than the rest of your home. The opposite of what your plants want.


Smaller humidifier models, like the cordless H2O humidifiers are very localised, so only make the air more humid directly around your plants, without risking a damp house. Some plants need higher humidity all year round but even the most hardy indoor plants tend to benefit from a humidity boost to get through dry winter days.


Before you invest in a humidifier though, first just get yourself one of those cheap hygrometers to keep an eye on the highs and lows to see if you actually need a humidifier.

 

Water can be a death sentence


This one might be a no brainer for you, but in my books it's best never to assume what someone does and doesn't know. Like washing hung out to dry in summer vs winter, everything stays wetter longer in winter, including your plant's soil.


Plants need less water in winter.
 Sometimes a thirsty, twice-weekly water-lover can drop their demands down to every 2 to 3 weeks or less over winter. Keep watering at summer levels and that might be the end of your relationship.


Watering too often is WAY more serious than not enough. Winter and root rot go together. And root rot can mean a sudden death sentence. Don't risk it. Some plants DO go dormant or die off over winter (I'm looking at you Caladium), so don't need water at all over winter.


Cacti would be another one you might want to give watering a miss over winter. Succulents I'd drop down to every 3 to 4 weeks depending on your conditions. ZZ maybe once a month, again depending on conditions. You really can't water to a schedule though, even more so when there's a change of season.


The finger test I find becomes unreliable in winter. In general, read up on your individual plant's needs, and check that soil down at root level before you water, and you should get through the winter water worries sweet as. 

 

sustee water meter in plant



If you don't have something that checks moisture levels down at root level - like a Sustee (that's the thing in the plant above), or a cheapy Water Meter or those clever little Soil Sensors - then at least grab a thin wood dowel (like a kebab stick) and stick it on down there. Take it out after a minute and see if the tip has changed colour or not. If it's dry, water away.


For Sustee it's really easy. Wait till window changes colour from blue to white. Only water when white. Those Soil Sensors also change colour. You press the sensor and a different colour lights up depending on the moisture level from wet, moist to dry. Whatever you choose, a moisture sensor of some kind takes a lot of stress out of watering in winter.

 No wet feet 


It's even more important to let plants fully drain in winter after watering, before putting them back in their cover pot. No wet feet! Even for ones I'm chill about bottom-watering in summer, or watering in their cover pot and tipping excess out later when I remember, I get paranoid about over winter. I still bottom water my Begonias, African Violets and Orchids in winter. I just set a timer so I don't go overboard and take them out of their bath as soon as the top of the substrate's wet. 

Don't underestimate the harm poor soil can do in winter also. If your plants are not ones that like staying wet, a substrate that has high water retention is all very well and good in summer, but could be a death sentence in winter. Consider repotting before winter into a light, airy, free-draining mix instead. Soil-based and peat-based mixes tend to retain too much water in winter, unless that's what you plants loves of course. I use peat-based mix for my African Violets and Peace Lilies for example. Keep in mind that repotting or potting up is a big deal for plants to cope with, so I'd only repot in winter if it really is necessary to fix poor soil.  


Either way, use this guide for what to do and not do when repotting so your plants don't die to help your plants recover without complications.


Propalicious


Roots that grow the moment you look away in summer, can get stubborn in winter, but there's no reason you can't chop and prop your way through winter if you spoil your babies with a bit of extra heat, light and humidity depending on their needs. That way they'll be ready for potting up come spring when the serious growth kicks in. 


I love propagating, especially in water where I can see the roots grow. Although I'm a shocker for getting around to potting them up later! But since I also have an aversion to throwing away cuttings when I tidy up my plants, I end up propagating all year-round.


I have a heat mat in a terrarium for most of mine which are lit by grow bars to keep heat, light and humidity high. However those little propagation mini pots (below) are superb for propagating in substrates like spag moss and fern fibre in winter without a terrarium, as they have a little built-in humidity dome for each mini pot. So cute too!


For faster rooting in winter so the stem doesn't rot before it's started growing roots, give fresh cuttings a dip in Clonex Gel. It not only gives them a dose of plant growth hormones but also helps seal and protect from root rot. You can use that in water or in solid substrates.


PS: I've been experimenting with Bio Leaf's Starter Mix recently with superb results used in these mini pots. Great combo. 

 



To feed or not to feed? That is the question


Many house plant hobbyists skip the fertiliser over winter. I personally feed lightly right through winter. As I fertilise every time I water, my plants naturally get less food over winter because I water less often. I've also found feeding lightly over winter has stopped the usual yellow leaves that my plants used to get every spring. 


The best way to decide I think is a bit of education, then you can decide what's best for your plant and your plant parent style. Here's what happens to plants nutrient needs over winter > and also why plants get yellow leaves >


I don't want deficiencies to build up over winter and impact all that lovely spring growth or cause yellow leaves that slowly die, so I do the 'weakly weekly' method which simply means feeding lightly, every time you water, all year round. I let my plant's reduced water needs dictate the amount of fertiliser they need. Here's more about the weekly weakly method >


What you can skip if you like, is all the growth boosters. The way I think of them is like your car's accelerator. Fertiliser is the fuel in the tank, and growth boosters are like putting your foot down on the accelerator. Whether natural or synthetic, if you want to give your plants 'a rest' as such, winter's the time to ease up on the growth boosters, and cut back to just your trusty plant fertiliser instead to get them through.


Keep in mind if you do keep giving growth boosters over winter, definitely keep up the fertiliser, or the growth booster will deplete your plant's stores of nutrients faster than usual to fuel that fabulous growth, and you could end up with deficiencies come spring. That is the main reason for yellow leaves come spring.

 

Pest alert


Creating an ideal environment over winter for our indoor plants can also be heaven for bugs to thrive through winter too. If you have any outdoorsy types who come inside over winter, make sure they don't bring any unwanted guests along with them into the warmth! Quarantine your outdoor plants separately for at least 4 weeks (that's about the shortest period to covers the lifecycle of most pests), before they get too cosy with their always-indoor buddies. I prefer to keep mine separate. Also keep inspecting your indoor babies for pests the same as you would over summer. Some like thrips love autumn, others like fungus gnats will cheerfully set up home in your plants all year round. How to get rid of fungus gnats once and for all >

 

Step away from that soil, put down the scoop

 

Repotting a plant is like surgery is for us. It's a major, sometimes with some serious recovery care required. The best time to repot most plants is from spring to autumn, when a plant's all about that growth. Roots often have a growth spurt late autumn leading in to winter, so you can repot later in the year than you might think.


Worst time to repot? Yep, winter. Of course if you HAVE to repot, like really hand-on-heart have to, pop your plant into recovery afterwards. That means warmth. A heat mat is pretty much a must for recovery from winter repotting in my books. This guide to repotting has a great section on recovery. 

 

Winter schminter!


There you have it. Lots of easy winter prep tips and tricks to get your precious indoor plants through winter safe and sound. If you found this helpful, please do give it a share. Shout outs much appreciated!

 

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