Ultimate Guide to Growing Giant Hostas in Your Garden

John Plant
1 day ago
5 min read

The American Hosta Growers Association defines giant Hosta as those that exceed 90cm in height. There are several cultivars now that are in the 120cm range or more. How big GIANT Hostas get in your garden depends on how much light they get, how much water they can get, and how deep and good the soil is. All three factors need to be optimum to achieve maximum size.

Hostas are beloved shade-loving perennials prized for their wide range of leaf colours, shapes, and textures. Their sizes span a full spectrum too, from cute miniature varieties under 15cm up to giant cultivars exceeding 120cm across!

While genetics determine their natural size potential, proper care makes all the difference in realizing the full grandeur of big Hosta varieties

Follow these tips to help your Hostas grow as enormous as possible

Choose the Right Variety

To grow huge Hostas, start by picking varieties specifically bred to reach very large proportions. Some top mammoth options include:

Empress Wu – 150cm tall with massive 60cm wide blue-green leaves, & up to 240cm wide.

Sum and Substance – Chartreuse 150cm wide clumps with 50cm long leaves, & height of up to 270cm.

Blue Angel – Vase-shaped clumps 168cm across with 40cm blue leaves reaching 90cm tall.

Komodo Dragon – A spread of up to 225cm with 90cm in height.

Frost Giant – an impressive variegated mound of 180cm wide & 80cm tall.

Gabriels Wing – a sport of Empress Wu, vase-shaped of 160 cm width & 80cm tall

Jurassic Park – impressive Hosta with a height of 140cm & spread of up to 270cm.

Give Giant Hostas Rich, Moist Soil

Hostas thrive in nutrient-dense, moisture-retentive soil amended with plenty of organic matter. Work in several inches of compost or rotted manure before planting. Mulch well after planting to conserve moisture and feed the soil as the mulch decomposes. Locate Hostas in naturally moist spots for best growth.

Deep rich soil is very much a factor in how large your giant Hosta can grow. Here in the UK up to ten inches of topsoil is fine. The higher the organic matter content is the better the soil will be. Incorporating 50% garden compost to the mix you backfill with is optimal. You can maintain a high organic content through the years by allowing a mulch to rot in place. The organic matter not only keeps nutrients in the soil and makes them available to your giant Hostas, it also helps water get into and stay in the soil.

Failure to provide near ideal conditions will result in an under-performing Hosta, that won’t reach its full potential.

Obviously, not everyone has the “perfect” location to grow giant Hostas to their potential. The solution is to amend the soil to help create a desirable site. Adding organic matter such as leaf mould or garden compost will help with water retention. After that it is up to us to water the Hostas when Mother Nature doesn’t do her part.

Allow Enough Space

Give each Hosta plenty of room to reach its mature size without crowding. Check spacing requirements for the cultivar and adjust accordingly. As a rule of thumb, allow at least 120cm or more for giant varieties. Space will determine ultimately how big your giant Hosta will grow. Not enough room will stunt their growth and might make them unhealthy.

Water Regularly

Hostas are moisture and shade lovers requiring moist soil to maximise their potential, especially as young plants and during growth periods. Water thoroughly at the base about 2cms per week, adjusting for rainfall. Consider installing irrigation in hot climates. Hostas growing in dry conditions will probably survive outdoors but will never reach full fitness.

Use a High Nitrogen Fertiliser

By feeding you Hostas with a high nitrogen fertiliser occasionally, together with your traditional organic feed will be beneficial to your Hosta. This nitrogen will help the leaves get and stay larger. Apply according to package directions in early spring.

Give Hostas Optimal Sun Exposure

Most grow best in part shade or morning sun only. However, gold and yellow varieties can tolerate more light. Variegated Hostas often thrive in about half sun. Adjust sunlight for maximal growth based on the variety. Plant you Giant Hostas in dappled shade avoiding the midday sun from 11am to 2 pm, during the summer.

Divide Hostas when Overcrowded

If your Hosta clump outgrows its space and leaves are smaller, it’s time to divide it. Carefully dig up and separate the plant, preferably in early spring, discarding any woody centres. Replant divisions with roughly 3 eyes or shoots each. This rejuvenates the plants. It also gives you free Hostas!

Control Snail and Slug Pests

These slimy creatures will riddle Hosta leaves with holes, stunting their growth, making a lovely statuesque Hosta look dreadful. The method of slug control will be down to choice, See my blog on slug protection. https://www.rewelahostas.com/post/how-to-stop-slugs-snails-eating-my-hostas-revisited

Remove any infested foliage to stimulate new growth. Keep mulch away from crowns as it shelters pests.

With the right growing conditions and care, all Hostas varieties can reach surprising proportions, and giant Hosta cultivars will astound you with their colossal growth when provided exactly what they need. Give your Hostas some extra sun protection. Hostas will get the best light if there are trees around it so that it moves with the sun.

Availability of water to the giant Hostas is a very important factor. Most Hostas receive about 150cm of rainfall annually in their native habitat of East Asia. Love and enjoy watching them grow into gorgeous, hulking specimens.

When water is withheld, the Hostas will stop growth. The crown won’t be able to hold as much food, so the plant will be smaller next spring. Location, location, location is the largest factor in determining available water. If you’ve been gardening in the same spot for a while, you know where the wet spots are.

Moist areas are the ideal spot for the giants. We’re not talking about standing water that has no oxygen in the soil. The best spot has soil that is likely to still be moist in the hot summer months.

How long does it take for Hosta to reach full size?

Some varieties of Giant Hosta grow quicker than others. It will depend on the variety, and the conditions the Hosta has been given as to how quickly it reaches maturity. They generally will take -5 years to reach maturity. Allow plenty of room when you plant to accommodate for their mature size.

Why is my Hosta staying small?

While Hostas certainly grow well in partial shade, they need a certain amount of light to thrive. If the surrounding trees have grown over the last five years, they may be shading out your Hostas. There is also the possibility that your plants are not receiving adequate moisture, which would stunt your plants.

Why are my Hostas not getting big?

It’s all about rainfall, good aeration (loose, airy soil), and consistently deep moisture. Root competition plays a very big part in stealing water from Hostas, and if you don’t get enough natural rainfall it can be almost impossible to water enough to keep them big.

Growing giant Hostas is fairly straight-forward given the right growing conditions and they reward you with a fabulous display of massive foliage. They are a stand out in any garden and given the right position can be a focal point of the area.