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Fertilizing hostas

Fertilizing hostas starts with adding nutrient-rich organic matter like compost or rotted manure into the soil prior to planting. You may also wish to mix in some starter fertilizer. After planting, mulch the soil surface with organic mulch.

Annual feeding usually consists of applying a balanced slow-release fertilizer in spring and early summer and sometimes with a nitrogen-rich foliar spray. Mulch is also replenished annually to continue the production of soil humus.

Introduction to fertilizing hostas

Fertilizing hostas is not a mandatory task for gardeners, but it certainly can help your plants grow as lush as possible. These plants grow wild in rainy climates with naturally nutrient-rich, well-drained soil. While it’s possible you have these conditions naturally, most gardeners aren’t so lucky and have to add mineral nutrients in the form of hosta fertilizer to their soil for truly thriving hostas.

There are a few key things to remember when fertilizing hostas:

  • Use a starter fertilizer and add organic matter when planting new hostas.
  • Apply slow-release fertilizers in spring and early summer.
  • Use organic mulches to improve soil quality and encourage growth.
  • Fertilize with a foliar spray every week or two in the early morning or evening.
  • Stop fertilizing hostas in midsummer to avoid tender late-season growth.

Fertilizing hostas start before planting them. Preparing soil for hostas is common and usually includes mixing in organic matter and starter fertilizer. Good options for organic matter include compost, rotted manure, coco coir, or other locally available bulk organic materials. This is also the best time to adjust soil pH if required.

Soil test
I took some soil samples in my garden and sent them off to a lab to see which nutrients were lacking in my garden’s soil.

Mulching the soil surface is the next part of fertilizing hostas. Use a nutrient-rich organic mulch such as compost. Organic mulches like hardwood mulch will break down over time to add humus to the soil for tilth and general soil health.

After planting hostas, fertilize them in spring and early summer with a balanced slow-release fertilizer. Most of these products are granular and are easy to sprinkle on the soil around the base of the hosta. Hosta lovers may also like to use a spray foliar fertilizer directly on the leaves. These are usually applied every week or two. Try to apply them early in the morning or in the evening (not in the hottest, sunniest part of the day).

Fertilizing hostas - basics

Starter fertilizer for hostas

Mixing in organic matter and starter fertilizer is common practice prior to planting hostas. The organics and fertilizer are usually mixed into the entire expected mature footprint of the plant. This can exceed 5 feet wide for giant hosta varieties! This can be tricky in heavy clay soils but is worth it for faster-growing vigorous plants.

Starter fertilizers are usually powdered or granular products that contain a high percentage of phosphorus. This nutrient encourages strong root growth and is essential for getting hostas off to a good start. Some excellent starter fertilizers for hostas include Espoma Bio-Tone Starter Plus and Down to Earth Starter Mix.

Slow-release fertilizer for hostas

Slow-release fertilizers are usually applied starting in early spring and applied again until midsummer. This fertilizer is applied to the soil surface and watered in very well. It’s crucial not to let the fertilizer granules touch the base of the plant, as this can cause stem and/or leaf burn.

A slow-release fertilizer contains nutrients that are gradually released over time, usually 8 to 12 weeks. This type of fertilizer is ideal for hostas because it reduces the risk of leaf burn and provides a consistent supply of nutrients. Some excellent slow-release fertilizers for hostas include Espoma Holly-Tone and Jobe’s All-Purpose Balanced Organic Fertilizer.

Mulch for hostas

Organic mulches are ideal for adding a slow and steady stream of nutrients. This is especially important in hot summer climates where hostas can go into a bit of dormancy.

Mulching also helps to regulate soil temperature, suppress weeds, and conserve moisture. All of these factors help reduce stress on the plant and encourage growth.

Some excellent organic mulches for hostas include hardwood mulch, shredded bark, pine needles, compost, rotted manure, and coco coir. These mulches break down over time and improve the tilth of the soil.

Take care to apply them over the entire soil surface under the leaves of the hosta, extending out past the drip line/edge of the leaves but also not touching the actual stems of the plant. Piling mulch up against the stems is a recipe for fungal disease. Keep the base of the plant open for good airflow, and be sure to water the soil around the plant rather than water it from overhead.

Hosta leaf with hand - mary jane duford
I love the bright apple green of my ‘guacamole’ hosta

Foliar fertilizers for hostas

Foliar fertilizers are applied directly to the leaves and are usually diluted with water according to package directions. These fertilizers are easy to apply with a pump sprayer or handheld spray bottle and can be applied weekly or twice. Be sure to apply foliar fertilizers in the early morning or evening.

Foliar fertilizers provide a quick shot of nutrients that the plant rapidly absorbs. Most include lots of nitrogen for good leaf growth and magnesium to boost photosynthesis. Some excellent foliar fertilizers for hostas include FOOP Mist and Bloom City SuperGreen Spray.

Fertilizer bags

When to fertilize hostas

The best time to fertilize hostas is in the spring. This is when the plant is just starting to break dormancy and is ready to start putting on new growth, as well as later in the spring when the plant is growing rapidly due to the warmer temperatures.

Fertilizing hostas in late summer or early fall can encourage new growth that is susceptible to slugs and potentially to frost damage from heaving. It’s best to fertilize hostas in spring and early summer and then stop fertilizing in midsummer. Late summer growth spurts tend to result in floppy growth that is irresistible to slugs and snails.

Mary Jane Duford
Mary Jane Duford

Mary Jane Duford is a quintessential Canadian gardener. An engineer by trade, she tends to an ever-expanding collection of plants. In her world, laughter blooms as freely as her flowers, and every plant is raised with a dash of Canadian grit.

Mary Jane is a certified Master Gardener and also holds a Permaculture Design Certificate. She's also a proud mom of three, teaching her little sprouts the crucial difference between a garden friend and foe.

When she's not playing in the dirt, Mary Jane revels in her love for Taylor Swift, Gilmore Girls, ice hockey, and the surprisingly soothing sounds of bluegrass covers of classic hip-hop songs. She invites you to join her garden party, a place where you can share in the joy of growing and where every day is a new opportunity to find the perfect spot for yet another plant.

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