Plants like drinking water similar to how they would in nature. Some plants are meant to sit in soggy soil, some to stay dry in sand. Some plants like a huge rush of water followed by a draining – maybe similar to a rising and ebbing of the tide.
I’ve had a bad habit of watering my plants every 2 to 3 days – when the top layer of dirt was just starting to dry out. I didn’t know then that if a plant sits in water for too long, it’ll cut down on oxygen in the soil. Roots need the oxygen that diffuses into the soil. More porous soil – and larger pores on average – allow for greater oxygen flow, as does less water clogging up the works. Constant wetness may also potentially cause root rot. Some terrible R&R for a plant, overall.
Back in the start of my balcony-gardening journey, I was concerned that any nutrients in the pots would cause root burn or other issues of the sort. I didn’t want to make the soil toxic. As a result, I didn’t add much fertilizer of any sort to any of my potted plants. I didn’t think that I could flush the soil if there was an overabundance of nutrients. I had worked out what state the soil was in and just how much water to add to bring the soil up to optimum moisture. I just never followed proper watering techniques – letting some plants dry out a bit more, flushing the soil, and the like. It’s time for an overhaul so I can enjoy some more plants with a little less frequent work and worry.
(Who am I kidding? I’ll worry about my plants any time).
Make sure you follow proper watering techniques. If you notice signs of overfeeding – your leaves are turning yellow (out of season), leaves are getting crunchy and dry (like in my olive), curling and misshapen leaves – you may want to flush the soil. Begone, chlorine! Begone other salts and built up micronutrients!
The ends of the leaves may start getting brown and dry, especially when the Chlorine kind of salt is involved. This has been a symptom I’ve been ignoring and ignorant of for too long.
Salts (especially the chlorine side of sodium chloride) can build up in the soil over time, no matter how careful you are. There’s often a little bit in most water, and there will be some that comes from fertilizer, road salt runoff, even chlorine that settles down out of the air downwind from industrial processing.
Salt builds up in leaf tips and kills the leaf tissue. If the salt is an ongoing issue, older leaves have more built up and are the first to show the signs.
You can also look to see if there’s a white crust along the sides of your pot or over the top of the soil. That crust is also quite possibly salt. If you do have salt buildups that are intense enough to form a crust, please consider scraping the crust off, or repotting your plant and cleaning the old pot. That’s a serious amount!
It’s good to flush every few weeks or every month, especially if you haven’t been following good watering techniques. I know I haven’t – I need to get a new watering can that isn’t so constrained in size. (Mine is currently 1 liter, so I have to refill it many times during watering)
So how much water should be flushed?
Not so much that you wash your soil clean (and potentially wash away the microorganisms or rot the roots), not so little that you’re just continuing the same issues caused by lack of flushing.
It’s a rough guess until you try out amounts on your own potted plants and soils.
Here’s a general rule of thumb:
- Add water until it just starts to drip out of the bottom of the pot. Really take your time soaking the soil a bit at a time; don’t just dump everything in at once.
- Then, add about 25% more of whatever quantity you just added. If it took 1 liter to make the pot start dripping, add 250ml on top of that.
- Don’t add more than 50% extra. That’s the dangerous territory of washing the soil clean, not just rinsing it.
Benefits of using a drip tray:
When you water plants normally, about 10-20% of the water used should end up running out of the bottom. This water will often carry some of the water-soluble nutrients (made by microorganisms) out away from the plant. With a drip tray, the plant is able to soak back up these nutrients (and even microorganisms), potentially causing some harm to the plant – though cutting down on how quickly the plant dries out. This collected water can be instead used to water outdoor plants.
You don’t want soil to build up too many of the soluble nutrients created by microorganisms in the soil.
Some Balcony Examples
I started adding water to my olive planter. It’s about the size of 4 or 5 shoeboxes, in a cube. It took 2 and a half liters of water to begin draining out of the bottom – (I looked under my patio to see, and guessed about how much was dripping onto the ground). I added a bit more, so half a liter over plus another half liter, 1 / 2.5 = 40%. More than 25%, but I’d never really done this before. I’ll forgive myself once the leaves heal.
This is the easiest planter to water. I just had to peek under the balcony to see when water started to drip out.
Here’s how strawberries look with salt damage.
Full disclosure – I wasn’t practicing proper watering – I just added a bit every couple days to keep the soil moist. I didn’t do a full watering until draining.
Strawberries are especially vulnerable to salt.
For this kind of planter, I’ve taken the tray out from below it. This is the almost the easiest kind of pot to flush, because you need to remove the drip tray beneath it. I just added about 1/4 L of water at a time until water started dripping beneath the balcony; about 3/4 L. Then I added another 1/4.
The strawberry responded wonderfully within days, shooting up two bright new leaf clusters, and letting one of the stunted fruit swell.
And peppers can experience marginal leaf necrosis, wilt, and defoliation.
I really need to rinse this trough, though the water-retention space it has makes this a difficult process without flooding.
For this, I’m actually in the process of drilling more holes in the base to allow better drainage. I’ll plug these with little rubber stoppers when I don’t want it to drain.
Most plants are hardy creatures. They’re going to survive all sorts of watering methods and level of nutrients. Their growth will be affected, their appearance will change, but they’ll often keep on going. In nature, soil takes care of regulating many of the oxygen and nutrient levels in ways that the plants are used to already. Fungi, bacteria, insects, and climate cycles will take care of much of the work.
When we constrain plants to grow in small boxes of earth, we need to take care of all those processes. Balancing nutrients can be pretty time-consuming, and plants certainly need a hefty amount. Those nutrients can build up over time, sometimes over a very short time. Soil needs to be rinsed clean by flushing on a regular basis (at least for most plants – run a test or read up on others’ guides to find out if yours would be harmed).