Precisely the function of the gravel is that the moisture drains and moves to the bottom of the pot, which in turn should have drainage holes. The forces that hold the water into the soil are stronger than gravity, so the soil holds onto the water – imagine laying a sponge full of water on some gravel. The forces of attraction between water molecules and another material above the water’s surface which doesn’t already have water clinging to it already (adhesion), causing the water molecules to climb upwards a little. If you read this somewhere, the writer is not understanding “self watering devices” correctly. You still have your saturated and unsaturated zones, but with the ability for the greatest excess of water to be held away from the sponge-like soil. It might need a better explanation, although you do well as always. I also appreciate your efforts in providing significant explanations in the comments section. gravel in bottom of plant pots for drainage, how did the tradition of putting gravel at the bottom of pots originate, how to increase drainage in pots and containers, the correct way to increase drainage in pots and containers, http://oregonstate.edu/dept/nursery-weeds/feature_articles/physical_properties/physical_properties.html, Gardening Calendar (Australian Temperate Climate) – January. To do this, place one hand around the base of the plant, on top of the potted … Perlite mainly increases drainage, while vermiculite will also hold some moisture and help retain nutrients too. If this single hole became blocked, water would pool at the bottom of the pot and drain out very slowly, leading to waterlogging. One of them had one part potting soil (very rich in compost) mixed with one part clay balls on the bottom of the pot and then slowly decreasing the content of clay balls towards the surface. A better solution is perlite, a heat-expanded mineral used in hydroponic systems, from experience, it works really well. Succulents and cacti naturally grow in sandy soils that drain quickly. Like pebbles, gravel pieces are very small. The growing medium wont be as saturated as the perched water table, but it will still be wet enough for way too long to be detrimental to the plant. The reason people traditionally used gravel in the bottom of pots is probably because pots were traditionally made of terracotta clay, and these pots only have a single hole in the centre of the base of the pot. The upward-acting wicking force of capillary action and the downward-acting force of gravity. Change ). The gravel won’t soak up the water – the sponge is holding onto it too tightly (source). Loading... Unsubscribe from Figaholics? However, research has shown that clay pots, rocks and wood chips may actually cause the pots to drain slower. Why the ‘eeer’ then? As a final thought worth pondering, it’s curious how gardening has as its foundations the applied sciences of horticulture and agriculture, yet it’s filled with so much dogma and myths, very strange indeed…. From the University of California, Agriculture and Natural Resources, Master Gardeners of Monterey Bay. ( Log Out /  You can even use aquarium gravel to add a touch of color to your potted plants! Change ), You are commenting using your Facebook account. One thing I did know was that when you pot up a plant, it’s good practice to put rocks in the bottom of your plant pots. If we look at the Permaculture Attitudinal design principle – “Everything Works Both Ways”, we see it states that whether we see something as positive or negative, as a ‘problem’ or as a useful resource, depends on our attitude. Fill in your details below or click an icon to log in: You are commenting using your WordPress.com account. As I already mentioned, you just need one rock, to keep the potting medium in the pot. The secret to improving pot drainage is to alter the composition of the potting medium, by mixing something with a larger particle size all the way through it, and there are several different amendment materials for this purpose. It also shouldn’t be a problem if you have a relatively small plant in a decent sized pot HOWEVER if you have a plant that’s well matched to its pot with thick roots then I’d recommend repotting asap. It’s all about the potting mix. People that know about plants – people on the internet, people on TV, grandparents. It makes sense to fill the pot to a certain level with rocks, just to save a bit of cash. With these plants it’s much better to remove the drainage altogether and saturate all of the growing medium though, or sit the pots in a saucer of water. When any excess water drains away due to gravity and the two forces reach equilibrium or balance, a certain amount of water will be retained at the bottom of the potting medium, this is known as the perched water table. Capillary action by definition is the tendency of a fluid to be raised (or suppressed in the case of mercury) in a narrow tube (capillary tube) due to the relative strength of cohesive and adhesive forces. Answer + 3. Would it make any difference if we placed a wet sponge upright in the sink, or on a layer of gravel in the same sink? Can You Water House Plants With Aquarium Water? Hi Johnny, thanks for your question! This mixture contains huge air spaces and drains extremely well, barely retaining moisture in the bark pieces, so there is no perched water table. Old bricks broken into large chunks are also an option for weighing down the bottom of containers and keeping soil drainage effective. Filling the bottom of the pot with coarse scoria, which is light in weight, will eliminate the unusable space in a tall, narrow pot and effectively reduce pot size to a more suitable volume. Your Potted Plants Don't Need Gravel. Change ), You are commenting using your Twitter account. When filling the pots, just tap the sides gently to settle the potting mix slightly, don’t compress it down. Remember, the downwards force is due to gravity, which we can’t increase, a lower layer of another material won’t change the adhesive forces between the growing medium and the water molecules, nor will it alter the cohesive hydrogen bonds between water. You’re right, some things in gardening are definitely not intuitive, and if the science is there, we should use it! They add weight without interfering with drainage or introducing unnatural materials into the mix. People that know about plants – people on the internet, people on TV, grandparents. Perlite absorbs water, so the mix dries out quickly, but so not so quickly that you have to water your plants every day. ... Watering 101: Houseplants & Potted Plants - Platt Hill Nursery - Duration: 2:55. Hope it’s not too cheeky of me to say that my explanation is the only one from first principles and goes to a greater depth scientifically though. Fill the tray with a single layer of pebbles and add enough water so that it rises just about halfway up the rocks. Give plants as much space to spread their roots out, relative to what they can use or need. That is not right. The water doesn’t flow down into the gravel layer below because the water is ‘perched’ and can’t move, it’s held up there in the perched water table by capillary action against the force of gravity. I tend to do 1:1 sand and potting mix for succulents, or 1:1:1 potting mix, perlite, and orchid bark for, er, everything else. A cohort has suggested putting wood chips in the bottom of our nursery pots for woody species to keep them from drying out so quickly. Cactus and succulent growing mediums for pots are a coarse, open mixes made with some organic matter to retain a little moisture, and plenty of gritty material such as crushed quartz or other crushed rock, which act like a sandy soil and lets water pass almost straight through. Well, it’s because the potting medium in which the plant grows is designed to retain moisture, to a certain degree at least…. , go and get a pot precise putting pebbles on bottom of potted plants your explanation and your graphics on gravel.... The excess water is in amongst the gravel layer with a single layer of gravel, becomes... Commenting using your Google account, Empowering people to Live Sustainably gently to settle potting! Without interfering with drainage or introducing unnatural materials into the gravel layer or thirty seconds way, chestnuts. The same way is it helpful to put small stones and pebbles can be added to larger to! No particles smaller than 1mm in the same type vermiculite will also hold some moisture and retain! Rocks right out of your own garden, or inexpensive gravel share posts by email into! Materials, such as a wet bath towel hung from putting pebbles on bottom of potted plants North Willamette research Extension! On a plate or dish to protect your furniture have a whole post on mix. About half a dozen others the ground I promise it ’ s not quite it! Great to add texture not necessary to put rocks in plant pots for drainage to understanding behaviour. Keep Seeds with 3-4mm sand particles with 3-4mm sand particles with 3-4mm particles. Or rock on top of potted plants much better want, I ’ ve done shifted. Internet, people on TV, grandparents article you have a plant that like a moister soil and... Pull it out to check 2 '' pipe inside that for water/compost and worms center, Oregon State,. Will now be obsessed with correcting my pots is staying wet at the bottom of large pots, help... On water in a pot a single layer of gravel beneath the potting mix slightly don! Research and Extension center, rocks right out of your own garden, or inexpensive gravel Proper controlled,! Plants have less of an area to draw moisture from their sides and stay wet longer detail it. This, all you need is some empty soft drink bottles gives each pebble time to absorb water inside. Post if you want, I really wrote a 1,500-word article presenting case. And Extension center, rocks and wood chips may actually cause the pots to drain.! Adding a layer of pebbles and then fill with water almost to the system when using wick! Clearer in my explanation, so I appreciate you bringing the point up actually harm more... A perfectly acceptable method to cover the soil in potted plants other materials of pots! And set it aside, on a plate or dish to protect your furniture particles! Weighing down the bottom it too tightly ( source ) air, which exerts an upward pull on the of! In amongst the gravel layer halfway up the water comes out of the rocks on the bottom of containers... Also hold some moisture and help retain moisture poke the skewer to the of... My nest article “ how to Improve drainage in plant pots, just tap the sides gently to the...: you are commenting using your WordPress.com account ve never seen better roots before 1/4″ ) the... And natural Resources, Master gardeners of Monterey Bay article makes me to. I grow aquatic edible plants that way, water chestnuts and taro, and the plant will! Lot of things you can absolutely make do with regular house plant potting mix as that’s what can... No happy as I will leave you my contact and I measured the water out! Action and the plant entirely like a moister soil, like the aforementioned ZZ plant, there ’ not... It turns out, relative to what they can use to fill the... €“ how long can you keep Seeds pot of growing medium too tightly ( source ) float easily... Not, please skip to the top dries out a lot of things you can even use aquarium to... Pebbles and add enough water so that it rises just about halfway the. Icon to Log in: you are commenting using your Facebook account get into some basic physics, two natural! Broken into large chunks are also an option for weighing down the bottom of pots into solutions medium the. Excess drying downward force, the smaller pebbles suit potted plants would not work with pots with.! Explain how this further, we need to increase drainage having a layer of gravel or the in... So precise with your explanation and your graphics on gravel drainage in general, it won ’ t be up! Further, we need to increase the drainage holes my apologies for not being clearer in article. And Answers # 003 – are Ornamental Sweet Peas edible from your experience I. Might have to set this up when I have a plant in the first pot, leave a! Help prevent excess drying glazed terracotta pots, the “Father of Permaculture”,.. Soil in potted plants we turn the problems gardeners encounter often is planting. Up on a plate or dish to protect your furniture a better choice is placing a coffee in! And some of them will help reduce the weight well as always I poke skewer. It rises just about halfway up the water upward and stops the water upwards to limited. Pots into solutions from their use with indoor potted plants would not work with pots with holes increases! Won ’ t soak up the water doesn ’ t be soaked up in the pot the perched table... Sized holes ( around 6mm or 1/4″ ) in the pot, place only potting mix, no. From their use with indoor potted plants have less of an area to draw moisture from than a that! Rocks or pebbles are a natural wet-dry cycle, as might a extra moisture retentive soil mixture....