Miniature and Very Small Hostas
Miniature or Very Small?
Most hosta collectors think of a miniature hosta as one which grows no more than about 15-18cm (6-7”) in height. However, the American Hosta which sets the international standards for hostas now defines a miniature as one which has a mature leaf area of less than 6 sq.” (15 sq. cm). This means that some varieties with long narrow leaves with a width of 15 sq. cm. or less, are designated as minis even though their mature height may be up to 30cm (12”), for example H. ‘Stiletto’ and H. Hacksaw’.
Growing Miniature Hostas
Most miniature Hostas are trouble free and, like their larger relatives, are easy to grow.
Miniature hostas look great planted together in bowls or troughs, separately in pots, or in gravel beds. Some of the more vigorous varieties also look good as edging plants or on rockeries, but since they do not spread rapidly make sure they can’t easily be smothered by faster growing and spreading plants.
Always buy minis from a specialist supplier who will tell you if a variety needs special care. (Ask if they don’t tell you)! If you buy a ‘difficult’ mini, buy early in the season, to give it a full season’s growth before winter. The secret of growing miniature hostas well is to make sure they have very good drainage. Miniatures need a lot of air around their roots and hate sitting in water-logged compost over winter when wetness combined with a hard freeze can cause root rot. Since miniature and very small hostas often have fine and shallow roots, you also need to make sure they do not dry out during the growing season.
Miniatures like a light, well-aerated growing medium so to a general multi-purpose compost you will need to add about 40% horticultural grit, sharp sand or Vermiculite.
When you buy a miniature hosta by mail-order either bare-root or in compost, you will sometimes find little plantlets fall away from around the main stem when you plant them. Don’t be tempted to plant these separately. They are likely to die.
Miniature Hostas in Troughs and Bowls
The natural spread of miniature hostas varies, but given enough root-room and good growing conditions but in the open ground most will reach a diameter of 30cm or more, (12”+) when mature, far too big for most bowls and troughs. The good news is that miniature and very small hostas may take 3-4 years to reach this stage so even vigorous minis can be displayed together for at least two years before they need dividing. If planting in a trough or bowl, a. 4-5” depth of compost will ensure that your miniatures will grow well but not over-size. Also make sure it has plenty of drainage holes. You may have to drill some more.
If you are determined that you want the tiniest minis possible for a small trough or bowl, it is sometimes a mistake to choose those that seem to have the smallest mature height and leaf size. Often the smallest minis are those most difficult to grow well. These are the varieties that need to develop the largest root ball possible to thrive. In a trough or bowl with restricted root-room and competition from other minis they may struggle. Minis with a large amount of white in their leaves also fall into this category: e.g. H. Lakeside Elfin Fire, H. Pandora’s Box.
So, for the smallest mature plants, it is better to select a vigorous mini or very small hosta that will still grow well, even if its root ball is very restricted. Some miniature and very small hostas make wonderful accent plants for bonsai or look good by themselves in the smallest bonsai or accent pots. When planting in a very small pot, regular watering is important. After a year or two the plant may push itself out of the compost. In this case, root prune and re-plant as you would a bonsai tree.
Of course, miniature and very small hostas do not just look good planted together. 18cm bulb bowls are excellent containers for displaying minis, using ‘hosta theatres’ to raise them off the ground. Again, holes may have to be drilled in them for drainage.
If you are growing mini and very small hostas in bowls or pots, check at the beginning of the season to see if their roots are filling the pot. If they are, then tease out some of the old compost and replace with fresh, adding slow release fertiliser granules to the new compost. If the plant is pot-bound and you don’t want to divide or re-pot it, then root prune it by snipping off some of its roots with scissors and fill the space released with fresh compost as above.
Miniatures, like all hostas can be given an initial boost by using a weak seaweed feed (root stimulant) between March and May. White centred minis, i.e. those with little chlorophyll in their leaves, benefit from a weak feed through the summer, but do not feed after July, when the hosta is beginning to slow down for the winter. When choosing a fertiliser, choose one with 10-20% nitrogen content.
The best time to divide minis is when they are growing most strongly, i.e. from May to June. Before you divide, check that the root ball is a good size and that the plant has multiple eyes (leaf buds). To divide, depending on the size of the plant, first try to tease the plant apart, pulling and twisting whilst holding the crown of the hosta. Often the hosta will just come apart. Otherwise, use a serrated kitchen knife or bread knife to cut through the crown. Again, try to tease the roots apart. The rule for dividing is: ‘Don’t be too greedy!’ The more divisions you try to get out of one plant the more chance there will be of losses. Some hostas minis increase in size through underground runners. These are usually the easiest to divide since there is no central crown to cut through.
Over-wintering miniature hostas.
All hostas benefit from about 4-6 weeks dormancy in winter – temperatures below 4C. or 40F – so over-wintering minis outside in a severe winter isn’t a problem providing they have good drainage. Cold won’t kill a mini but being waterlogged, frozen, thawed and frozen might, particularly during its first year of growth. Mulch your minis with bark chippings or horticultural grit to help prevent crown rot and the puddling of water around the crown if there is a top thaw after a hard freeze.
Many people bring minis planted in troughs or bowls under cover during winter. A porch or car port is ideal. This protects the hostas from getting waterlogged by thick snow and winter rain and makes sure they get plenty of ventilation. This minimises the risk of crown rot. Never bring minis indoors – even into a conservatory. In a cold greenhouse it’s best to keep the doors and window vents open unless it’s blowing a gale. Then you can be sure your minis stay cold and dormant. It’s surprising how fast a closed greenhouse warms up with a day or two of winter sunshine. If you choose to keep your minis in a greenhouse keep a look out for whitefly on the compost and greenfly on the newly emerging shoot tips. Put your minis outside again mid-February and water from then on.
Starting out with minis
An easy to grow starter collection of mini and very small hostas might include H. Blue Mouse Ears, H. Cracker Crumbs, H. Crystal Dixie , Desert Mouse, Dragon Tails, Feather Boa, Frosted Mouse Ears, Green with Envy, Holy Mouse Ears, Hush Puppie,, Iced Lemon, Lakeside Baby Face, Lakeside Ninita, Lakeside Scamp, Lemon Delight, Lemon Lime, Lime Fizz, Limey Lisa, Little Caesar, Little Red Rooster, Little Wonder, O’Harra, Paradise Puppet, Paradise Sunset, Popo, Rock Island Line, Shiny Penny, Silver Threads and Golden Needles, Slim and Trim, Surprised by Joy, Tattle Tails, Teeny Weeny Bikini, Twist of Lime, Yellow Boa.