All plants have a natural form that they will grow into with time. As a mature plant, hostas each have a form and this should be used in the landscape to "play off" against other forms to relieve monotony and provide contrast.

It is important to remember that this factor applies to a mature clump of hostas. Many types will show one form of the other as a juvenile plant or seedling but, in a few years' of growth will transform into its mature form. Generally, it takes 5 or 6 years for a hosta plant to be considered a mature clump.

According to The American Hosta Society guidelines for registering new cultivars, there are three forms including mound-like, upright and rhizomatous. We have also included a commonly used term called irregular.

Mound-Like - This is the generally a "rounded" form that pertains to the vast majority of hostas in the garden. One variation on this theme is to call a hosta "dome"-shaped. Here you might  think of a sports stadium with a domed roof. H. 'Blue Cadet' is an example.

Some hostas form what is called a "flat" mound which means that they have a more horizontal orientation.  The species, Hosta longipes, would exhibit this trait.

There are also a few plants that have a "cubed" mound. In effect, these are square in form with a width that equals their height. H. 'Summer Fragrance' has a more or less cubed form.

Upright Hostas - This form is also sometimes called vase-shaped. Plants in this category have an exaggerated impulse to send their stems skyward. Therefore, they don't develop particularly wide mounds but have narrow bases with long, upward rising petioles.

These types of plants have the natural outline of an erupting volcano or water gushing up through a blow hole at the ocean's edge. Such natural forms are intriguing to people and plants that reflect them gain in interest. They also give a feeling of delicacy and finer texture. Examples of upright hostas would include H. 'Krossa Regal' and H. 'Yellow River'.

Rhizomatous Hostas - Let's get the biology straight right away. A rhizome is a modified stem that runs underground. A stolon is a modified stem that runs on top of the ground. This is important to know since many people and references will talk about hostas as being “stoloniferous”. I don't know how this got started but many hostas have been miss-labeled as such.

Actually, quite a few hostas expand and multiply by extending rhizomes out in all directions underground from buds on the crown. Being stems, these structures have nodes which house new buds. These buds have the ability to send up a stem and to develop roots below. This results in the formation of a new division of the plant.

Many of the small hostas such as H. 'Golden Tiara' which may be used as groundcovers are effective because they spread by rhizomes.

 

Irregular Shaped Hostas - Most hostas have some regularity to their form whether it is mounded or upright. However a few cultivars do not have such discipline and seem to be like untidy teenagers that throw their leaves around in all directions without any thought.