Salt Leaching Methods: Tips On Leaching Indoor Plants

By: Liz Baessler

Potted plants have only so much soil to work with, which means they need to be fertilized. This also means, unfortunately, that extra, unabsorbed minerals in the fertilizer remain in the soil, potentially leading to nasty buildup that can harm your plant. Luckily, there’s an easy process for getting rid of this buildup, called leaching. Indoor plants should be leached regularly to keep their soil clear. Keep reading to learn more about how to leach a houseplant.

Reasons for Leaching Houseplants

The minerals you’re getting rid of are called salts. They were dissolved in water and left behind when the water evaporated. You might see them in a white buildup on the surface of your plant’s soil or around the pot’s drainage holes. This is evidence that there are even more salts in the soil.

As these salts build up, plants have a harder time drawing up water. This can lead to browned, wilted, or lost leaves and slowed growth. If too many salts build up, the plant will draw moisture from its own root tips and die. For this reason, knowing how to leach a houseplant is important for its overall health.

Tips for Leaching Salt from Soil

Leaching indoor plants sounds intimidating but it doesn’t need to be. In fact, leaching salt from soil is easy. If you see visible white buildup on the surface of the soil, gently remove it, taking care not to take away more than ¼ inch (0.5 cm.) of soil.

Next, take your plant outside or put it in a sink or bathtub — anywhere lots of water will be able to drain freely. Then, slowly pour warm water over the soil, making sure it doesn’t overflow the rim of the pot. Pour twice as much water as the plant container would hold. For example, for a half gallon pot (2 L.), slowly pour a gallon (4 L.) of water.

The water will absorb the salts and carry them away. Leaching houseplants every four to six months will make for clear soil and healthy plants.

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Read more about General Houseplant Care

Watering and Soluble Salts - Indoor Plants

A large percentage of houseplants are lost because of overwatering and underwatering. Watering on a schedule is not the best method as this can lead to plants receiving too much or too little water. One way to determine when to water is to test the soil with your finger to a depth of about two inches. If the soil is dry, it probably needs to be watered. This method works for most plants but there are exceptions like succulents and cacti which need far less water. C ertain plants like p eace lily (Spathiphyllum) will wilt when they need to be watered although plants can also wilt if they are overwatered too . Another quick test is to lift the plant, pot and all, to check its weight change. The plant with dry potting medium will weigh much less than the plant which still has ample water in its potting medium. While you’re testing for watering needs, pay attention to the potting media. If your finger can’t penetrate two inches deep, you may need a more porous potting mix or the plant may be root bound.

There are a couple of ways to water watering from the top or watering from the bottom . Top watering is the most common method. Irrigate so that the water drains freely from the bottom of the container. Small plants can be placed in the sink and returned to their locations after the water drains. Any excess water should be dumped from drainage saucers. Bottom watering simply means putting water into the saucer or setting the container in a pot of water allowing the water to be absorbed and drawn up into the potting mixture. Empty out any excess water. Never let your houseplants sit in water.

Salinity and salt

The terms salt and salinity are often used interchangeably, and sometimes incorrectly. A salt is simply an inorganic mineral that can dissolve in water. Many people associate salt with sodium chloride— common table salt. In reality, the salts that affect both surface water and groundwater often are a combination of sodium, calcium, potassium, magnesium, chlorides, nitrates, sulfates, bicarbonates and carbonates (Table 1).

These salts often originate from the earth’s crust. They also can result from weathering, in which small amounts of rock and other deposits are dissolved over time and carried away by water. This slow weathering may cause salts to accumulate in both surface and underground waters. The surface runoff of these dissolved salts is what gives the salt content to our oceans and lakes. Fertilizers and organic amendments also add salts to the soil.

Melinda Myers

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Improve the health of your houseplants and the look of your indoor garden with a little container clean up.

Scrape off any white crusty substance collecting on the lip of the container or soil surface. This build up of salt from minerals in fertilizer and hard or softened water can damage plants. High levels of these excess salts can prevent plants from absorbing the water they need, stunt growth and burn root tips, leading to rot.

Repeatedly and thoroughly water, called leaching, to wash any remaining salts out of the soil. Water the plant thoroughly until the excess water drains out the bottom of the pot. Use twice as much water as the container will hold. For example a 6 inch pot holds 10 cups of water, so use 20 cups to wash out the salts. Wait 30 to 60 minutes and repeat.

Repeat every six months or so to prevent plant damage.

A bit more information: Reduce the risk of salt build up by always watering thoroughly and pouring off excess water. Fertilize only when your plants are actively growing. And use a dilute solution, about one fourth to one half the recommended rate, when fertilizing.

10 Ways to Use Epsom Salts in the Garden

You’re probably familiar with the amazing, healing properties of Epsom salts. But did you know these minerals are a powerful superfood for your garden too? Inexpensive, natural, and non-toxic when used correctly, Epsom salts—the common name for the magnesium-sulfate compound (MgSO4)—can be a great boon to virtually anything you hope to grow. Magnesium-sulfate (which looks like ordinary table salt) can help increase nutrient absorption in plants.

Before working with Epsom salts in the garden, be aware of some precautions. Agricultural or technical grade Epsom salts are intended for garden and outdoor uses but only brands marked “USP” are suitable for humans, having been tested and certified by the FDA and United States Pharmacopeia (USP). Also, despite its overall safety, Epsom salts have natural laxative properties, so be sure to keep bulk salts away from children and pets. Magnesium-sulfate is absorbed through the skin as well, so wear gloves when applying it to your plants. Finally, it’s also wise to test your soil first to learn what minerals are low or lacking use Epsom salt in the garden only if the soil tests low in magnesium.

Clear these safety concerns and you’re bound to find that, unlike most types of chemical fertilizers, Epsom salts will not build up in your soil or poison your groundwater, yet will yield stronger seedlings, more bountiful blooms, tastier fruits, decreased pest damage, and increased resilience. Here are 10 simple, potent uses for Epsom salts every gardener should know.

1. Give Seeds a Better Start

Magnesium boosts seed germination by strengthening cell walls and providing increased energy for growth. Sulfur is easily lost during the germination process, so apply a drench of one tablespoon of Epsom salts for every gallon of water to the soil after seeding. Alternately, you can mix one tablespoon of Epsom salts into each hole before planting seeds. For grass seeds and wildflowers, sprinkle one cup Epsom salts per 100 square feet, blend into the soil, and water thoroughly. Reapply an Epsom salt drench to seedlings every month during growing season.

2. Increase Nutrient Absorption

Scientific tests indicate that magnesium-sulfate can increase cell uptake of key minerals, including nitrogen, phosphorus, and sulfur. In one recent study, testers in five states gave pepper plants a standard drench of one tablespoon Epsom salts to one gallon of water, twice a month, and a majority of the treated plants showed thicker foliage and larger vegetables.

3. Prevent Root Shock

Transplanted roots need tender care. To prevent root shock, which causes wilting and leaf discoloration, mix one tablespoon of Epsom salts for every one gallon of water and apply to the roots of newly re-potted plants until saturated. Or try adding one to two teaspoons of dry salts directly to the hole before transplanting a bush or flowers. After tamping down the soil, water thoroughly.

4. Deter Pests Naturally

Instead of using plain table salt to dehydrate and kill snails and slugs, banish the pests with Epsom salts and you’ll give roots and blooms a boost in the process. For general pest control, mix one cup of Epsom salts with five gallons of water and spray onto foliage. For slug and snail control, sprinkle dry Epsom salts in the garden around the base of plants.

5. Add Vibrancy

Mineral deficiencies can interfere with photosynthesis, leaching green color from leaves and interfering with nutrient absorption. If more mature foliage is turning yellow and curling, this may indicate a magnesium deficiency. Try a foliar spray of one tablespoon of Epsom salts mixed with four cups of water for each foot of plant height. Magnesium absorbs well if applied directly to the leaves.

6. Boost Flavor

Every month during growing season, mix one tablespoon of Epsom salts to each gallon of water and apply liberally to the roots of fruit and nut trees, grape vines, and berry patches. Another technique is to apply two tablespoon of dry salts over a nine-foot root-bed area, three times a year.

Sweet peppers and tomatoes also benefit from adding some Epsom salt to the garden soil. Before planting seeds, add one to two tablespoons of Epsom salts to the soil of each hole. During the growing season, apply a foliar spray of two tablespoons of salts to each gallon of water. Apply to leaves once a month.

7. Grow a Lush Lawn

If your soil tests positive for magnesium deficiency, Epsom salts will help your lawn achieve maximum growth and lushness. The Epsom Salt Council recommends applying three pounds of salts for every 1,250 square feet of lawn with a spreader. Sprinkle the salts lightly, then water your lawn with a hose or sprinkler system.

8. Heal Your Houseplants

Epsom salts are pH neutral and gentle on plants, including potted houseplants. To boost nutrient intake, mix two tablespoons of Epsom salts with one gallon of water and spray onto leaves, rather than onto the roots, for maximum absorption. Alternately, add the salts directly to the soil: one teaspoon of salts per each foot of plant height. Try adding Epsom salts to your houseplants every month, monitoring subtle changes in leaf vibrancy and growth.

9. Remove Tree Stumps

Professional stump removal services can cost between $60 and $350, depending on the size of the trunk. For a do-it-yourself means of removing a tree stump, though, you can enlist Epsom salts to kill the remains of a cut tree first. Bore holes all around the top of the stump with an electric ½-inch drill bit these holes should be about half the depth of the stump and spaced a few inches apart. Then, pour dry Epsom salts into the holes and slowly add water to moisten, but not saturate, the salts. Cover the stump with a tarp to repel rain and ensure the drying process. The salts will dehydrate the wood over several weeks, and as the wood dries out, you’ll be able to chip away most of the stump with an ax and soon dig up and dispose of the root system.

10. Produce Bountiful Roses

The magnesium in Epsom salts benefit both new and established rose bushes, helping to supplement a slow-release rose fertilizer containing nitrogen, potassium, and phosphorus. Before planting a new rose bush, add one tablespoon of Epsom salts to the bottom of each hole. For established roses, add one tablespoon of salts for every gallon of water and spray foliage when plants begin to leaf in spring and once again during flowering.


Leaching in soil can affect your crops because it takes away the essential nutrients that the plants need to grow. But more importantly, leaching has a profound effect on the whole environment. If possible, avoid using harmful chemicals to boost your harvest. Every single drop of chemical that will leach to the ground and bodies of water can affect the environment.

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