Growing Hostas
Hostas are shade-tolerant perennial plants which die down in the Autumn and come back each year in Spring. They are fully hardy, originating in China, Korea, and Japan where winters can be severe.
Hostas are primarily grown as foliage plants, since their leaves come in a spectacular range of colours, variegations, shapes and sizes. There are many hostas with blue foliage, the rarest colour in the plant world. Hostas come in a huge range of sizes from miniatures only 10cm (4”) high to giants up to 4’ high with leaves over 60cm (24”) long. Leaf shapes also vary from thin strap-like leaves to almost circular.
Although usually grown as foliage plants, hostas flower, colours ranging from purple, through shades of lavender to white. Some flowers are fragrant.
Hostas look good almost anywhere, from beds and borders to gravel gardens and rockeries. They also make marvellous container plants. Miniature hostas look wonderful in troughs, bowls and raised beds.
Planting Hostas
Hostas enjoy a neutral to acid soil, and, like most perennial plants, like it to be rich and well drained. To give them the best start, plant in multi-purpose compost or a mixture of compost and good garden soil. Some organic composts such as John Innes, tend to be quite fine and can become waterlogged in winter. So, we mix our own compost, especially for young hostas. In a large (40 litre) trug we mix two-thirds compost with a third other materials to create a rough compost. You can use mini bark chippings, composted bark or even pea gravel and pebbles. To this mix, add a handful of slow release fertiliser pellets.
Sun Tolerant Hostas in full sun
Our Shade Garden
Unless listed as ‘sun-tolerant’, hostas should be planted where they are likely to be in shade during the hottest part of the day. Morning sun is beneficial to most hostas, especially those with a lot of white in their leaves. Sun won’t kill a Hosta, but the thin-leaved varieties may burn in really hot sun. Bright sun will also change the colours of some hostas (e.g. turning blue to green-blue and cream to white.) Some thin-leaved gold and lime-green hostas, e.g. H. Fire island, H. Cherry Tart, H. Paradise Island will also bleach out and are best in shade.
Planting in Containers
Virtually all hostas are suitable for planting in pots and containers. To deter slugs and snails try placing fine mesh or porous landscape fabric over the drainage holes in the bottom of the pot before filling. We find a piece of fine windbreak/shade netting works well. Put crocks, small stones or pea gravel in the bottom of the pot to improve drainage. After your hosta has been in its container a year or so, check the roots. If it is pot-bound, then you can re-pot into a larger container. If you need to keep it in its existing container, a root prune will reinvigorate it every couple of years. Take off an inch or two of root with scissors or snips and fill the space at the bottom of the pot with new compost, adding a granular slow release fertiliser. A pot-bound hosta won’t mind an all-round root prune, using a bread knife or similar, to release some growing space.
Hostas in Containers
Hostas and Water
Hostas are well-known as moisture loving plants and it’s probably true to say that if you want your hostas to grow quickly and to their maximum size, and to look good all season, then they can take as much water as you can give them. The good news is, though, that hosta roots store water and most of the 250+ hostas in our garden seem to manage very well without extra watering.
Sometimes though, you may find that a hosta ‘sticks’ after three years or so, refusing to grow any larger. Unless it’s a variety renowned for this (e.g. H. ‘Great Expectations’, H. ‘Fire and Ice’), then the problem is probably insufficient water. The leaves of large hostas may stop rainfall from getting to their roots. Hostas in pots that have become root-bound or have been allowed to dry out may still have dry roots, even after a heavy watering. Keeping pots in a saucer that is constantly topped up helps here but make sure you remove it before winter. Hostas planted next to a hedge or under trees have to share their water so will need extra to grow to their full size.
Dividing Hostas
Hostas take between 4-8 years to grow into a mature plant, depending on the variety. Hostas can be divided as soon as there are multiple ‘eyes’ (little buds) around the crown of the plant. These can often be felt just under the surface of the soil, but be careful not to break them off with a searching finger! Some slow-growing varieties may take three years or more to reach this stage. Others may be dividable in no more than a year.
To divide a large mature hosta it’s best to wait until spring when you are not battling with too much foliage and can see the new leaf buds. Loosen it from the soil as much as you can and then cut partly through the crown with an old saw rather than trying to cut or chop it with a spade. We use a pruning saw to cut through the woody crown and then tease the parts of the plant apart. This minimises root damage. A very old hosta can be cut into several new plants – take the new plants from around the crown. We often cut new plants from around the edge of the hosta and replant the rest where it came from. If there are few buds in the centre of the plant, it means the crown has grown so woody, nutrients aren’t able to get through to the leaves. In this case, it’s best to discard the central crown.
Smaller or younger plants can be dug up or removed from their container, hosed around the crown to reveal the eyes and then divided with a bread knife. Eyes may not grow evenly around the plant and washing the crown means you can make sure your divisions are of equal size (similar number of eyes on each division). Again, cut through the crown and tease the roots apart.
The best time to divide is in late spring to mid-summer when growth is at its fastest. This gives the divisions time to fully recover the same season. The only downside to dividing in spring is the danger of damaging new shoots and leaf buds. Large, well-rooted hostas can just as safely be divided in autumn after the leaves die down. Miniature hostas are best divided from late May to early July.
Feeding Hostas
Hostas will benefit from some help at the beginning of the season, particularly those in pots. The new season’s roots don’t begin to grow until the first leaves have been fully open for about 3-4 weeks, so feeding with a root stimulant such as Seaweed Feed is beneficial between February and May. Hostas are not voracious feeders but some slow growers and those with a lot of white in the leaves, e,g, H. ‘Fire and Ice’ will appreciate a feed from time to time. Use a high nitrogen feed (10-20%) early in the season, then a balanced fertiliser. For large hostas chicken manure pellets can be scattered around the plant and gently forked into the soil. When planting or re-potting add a granular slow release fertiliser to your compost.
New Root Growth late May