Using Epsom salt for hostas is a standard of hosta growers, some debate its effectiveness. I dove into the science to find out. Does Epsom salt help hostas?
There is no proof of Epsom salt aiding healthy plants in many of the ways gardeners describe. However, Epsom salt is great for hostas that are lacking magnesium, which is an essential element for their growth. Magnesium-deficient hostas will show healthier foliage after Epsom salt treatment.
Below, we’ll discuss how to tell if your hosta needs more magnesium, and how to fertilize hostas with Epsom salt. We’ll also address the question: is it ever okay to give Epsom salt to a healthy hosta?
Can You Use Epsom Salt for Hostas?
We can use Epsom salt on hostas as a fertilizer to provide the plant with magnesium. Benefits of magnesium for hostas include:
- Aids photosynthesis by helping the hosta to create chlorophyll
- Promotes healthy cell division and protein formation
- Increases the hosta’s ability to retain water
- Allows the hosta to take in and use phosphorus
Without enough magnesium, your hostas will slowly die. But how can you tell if your hostas already have enough magnesium in their soil, or if they need more?
If your hostas appear healthy, it’s likely that your soil has an adequate amount of magnesium. Fertilizing with Epsom salt would be useless, and might even cause harm to the plant.
Signs of a magnesium-deficient hosta are:
- A hosta’s oldest leaves are yellowed around the veins, while the veins themselves remain green
- The hosta’s leaves turn purple, red, or brown
- The hosta’s growth slows
Magnesium deficiency is most likely to occur when using sandy, acidic soils.
Nutrient deficiencies are also common in soil that’s been untouched in a potted container for years, because the plant is using the nutrients, and the soil has no way to replenish them.
Soil in the ground is much less likely to be magnesium deficient.
Does Epsom Salt Help Hostas Grow?
Whether Epsom salt will help your hostas grow depends upon what their current soil is like.
If your hostas have a magnesium deficiency, Epsom salt will make a visible improvement in their growth. It will help them stay alive and, eventually, to thrive.
On the other hand, healthy hostas that are receiving proper nutrients will be unaffected or potentially even negatively affected by Epsom salt.
What Does Epsom Salt Do for Hostas?
Epsom salt’s main usage is to provide hostas with magnesium. It can bring a yellowed plant suffering from magnesium-deficiency to lush, green glory.
We can also use it alongside other fertilizers to fix nutrient-deficient soil.
That said, there are a lot of unproven benefits of Epsom salt in plants. The following are some myths not proven by science.
- Epsom salt is not a pesticide.
- Epsom salt does not affect seed germination.
- Epsom salt does not affect soil pH.
- Epsom salt does not to produce more growth, blooms, or produce in healthy plants. (Studies on this are inconclusive, with some citing increased or bettered produce and others citing a decline in quality.)
- Epsom salt is not proven to make healthy plants greener.
In summary, Epsom salt isn’t a magic cure for all of your plant and soil problems. But it does its job—providing magnesium—well.
As long as you remember its use, it’s a great tool to have in your gardening arsenal.
Will Epsom Salt Kill Hostas?
Is Epsom salt good for hostas? Yes, and no—it depends how much magnesium already exists in their soil, and how much Epsom salt you apply.
Like people, hostas need a certain number of nutrients to thrive. Too little, and they have a deficiency. But too much of a good thing can be just as detrimental.
Just as humans may get a blood test before taking random vitamins that they may or may not need, the best thing is to test the soil to see what nutrients it contains, and in what amounts.
Another solution is to limit the amount of Epsom salt given to healthy hostas.
Too much magnesium can:
- Cause fertilizer burn
- Kill beneficial microbes within the soil
- Cause aluminum to release from soil and harm plants
- Cause the plant to be deficient in other nutrients such as boron, iron, manganese, potassium, and calcium
Over time, one or a combination of these things can kill your hosta.
However, providing a small amount of Epsom salt as needed or during fertilizing will not kill your plants.
How to Apply Epsom Salt to Hostas
Epsom salt can be applied to hostas in a variety of ways. Watering hostas with Epsom salt, sprinkling Epsom salt directly onto the soil, and spraying foliage with Epsom salt are the most common. Epson salt can also be mixed with fertilizer when using a liquid feeding program.
Watering Hostas with Epsom Salt
- Mix two tablespoons of Epsom salt into a one-gallon container of water.
- If desired, add other water-soluble fertilizers to this solution as well. Make sure the other fertilizers don’t include magnesium, as you’ll risk overdosing your hostas.
- Water your hostas as usual, drenching the soil. If your hosta is potted, saturate the soil until water seeps from the drainage hole at the bottom of the pot.
Spraying Hosta Foliage with Epsom Salt
- Mix two tablespoons of Epsom salt into a one-gallon container of water (or the equivalent in a spray bottle).
- Spray the leaves with the solution. Alternatively, pour water directly onto the foliage for similar results without a sprayer.
Adding Epsom Salt Directly to Hosta Soil
- Start with a magnesium-deficient soil base.
- Sprinkle Epsom salt on the top layer of soil around the plant. Water thoroughly to allow the Epsom salt to seep into the soil.
- If adding Epsom salt before potting, mix thoroughly to evenly distribute the Epsom salt. (Do this before watering to make the process cleaner!)
What plants can you put Epsom salt on?
Any magnesium-hungry plants can benefit from Epsom salt. Before using Epsom salt on plants, ensure that the plant or its soil has a magnesium deficiency. Healthy plants will not benefit.
What can I put on my hostas to keep the bugs from eating them?
Epsom salt does not work as a pesticide. To keep bugs from eating your hostas, first identify the pest. Then, you can look into either natural solutions or pesticides that treat the infestation.
Do hostas like coffee grounds?
Coffee grounds provide nitrogen to plants, so hostas that are nitrogen-deficient will benefit from coffee grounds in their soil. Mix coffee grounds into the soil. See our article do hostas like coffee grounds to learn more.
Epsom salt is a significant source of magnesium, which can help hostas enormously when needed. However, unnecessary use won’t help your hostas and might cause damage.
Testing the soil for nutrient levels is best, but this is a pain for casual gardeners. If you just want bushy, thriving hostas, limit Epsom salt usage to irregular fertilizing or forgo it all together in healthy plants.
Instead, try providing your hostas with other key resources such as lighting, soil, and water conditions. These will go a lot further in maintaining plant health.