Why You May Be Watering Your Houseplants All Wrong

We all know that indoor plants need water to survive, but do we really know how much or how little? It’s not easy to keep container plants looking their best, even with regular watering schedules. You can change all that, though, by changing how you water. These simple techniques will restore your houseplants to their former greenhouse glory while ensuring they not only survive, but also thrive well into the future.


If you don’t think your potting soil feels like soil, you’re right. It is actually a soil-less mix composed of different quantities and sizes of organic and inorganic ingredients. These may include sphagnum moss, aged bark, compost, sawdust and/or coir (organic) and sand, perlite, vermiculite, rockwool and occasionally polystyrene beads. The different particles bind together in various ways to give potting soil its ‘fluffy’ quality.

Sphagnum peat moss is the most commonly used ingredient in potting soil and usually accounts for 50 to 75 percent of the mix.


In potting soils, porosity is key because it allows water and air to move easily through containers. As water passes through the pot, it travels through these pores, attaching itself onto some particles (that hold on to the moisture) and flowing past others.

This makes sense when you consider that your indoor plants have to somehow survive while housed in a pot. Unlike outdoor plants that can continuously nourish themselves from nutrient-rich soil, indoor plants are confined to their own little container. It’s up to you to manage their world.


Most importantly, don’t be fooled into thinking that your indoor plants would prefer actual soil. Garden soil is too heavy and compacted and its pore spaces are too small for indoor plants. As a result, it will reduce your houseplants’ ability to absorb water and air that is essential to their wellbeing.


Contrary to popular belief, pushing or pressing down on the potting mix is not helping your houseplant. Soil-less mix is all about aeration and porosity to allow water and air to infiltrate the soil. If you tamp down on the ‘soil,’ you are cutting off a vital source of air to your plants’ roots. Instead, make sure the potting mix stays fluffy and light to ensure the best conditions for your plant.



By now, most of us know that plants should be watered deeply and less often. But, how many times have you watered your plant thoroughly only to discover it felt dried out the next morning? The answer lies in the structure and texture of your particular potting mix and how long it takes for the different particles to absorb water.

For instance, you may have noticed a build-up of what looks like salt on the ‘soil’ surface. As potting mix decomposes, it creates more minerals, especially salt, that over time cause the plant to decline. The water you’re using can contribute to this problem, too. While your houseplant may have started out in the greenhouse with a healthy mix of minerals, over time, salt build-up can spell disaster for plant health. Much like when we eat more food than we need.


Photo: about.com

To prevent this problem, it’s important to flush plants regularly with water to help wash the salts and additional minerals away. Happily, this is also the most effective way to water. Place your plants in the sink and irrigate them slowly for up to a minute (gradually, not full-on from the spigot.) This will enable the salts and other accumulated minerals to wash through the soil and on out through the drainage holes.


Leave the pots in the sink for an hour so that they drain completely. It may seem like over-kill, but this will enable the particles in the potting mix to thoroughly absorb the water and hold on to it for days. Never place your pots immediately back on the saucer. Tender roots hate to be stuck in water and they’ll rot, causing the plant to eventually die. Be patient, it’s worth it.

Replace your pots on the saucer and enjoy knowing that you have restored your plants to optimum conditions for good health and longevity. Allow the top few inches of the soil to dry out before watering again.


A word on fertilizing, with all the salts and minerals building up in the pot, there’s little reason to fertilize as often as you’re probably doing. Fertilizing at a 1/4 to 1/2  strength every other week during the growing season is sufficient to keep your plants healthy and looking their best.


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About carole funger

I'm a landscape designer and Maryland Master Gardener living in the Washington, DC area. I blog about new trends in horticulture, inspiring gardens to visit and the latest tips and ideas for how to nurture your own beautiful garden. Every garden tells a story. What's yours?

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