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Are Hostas Good Under Trees?

Natural shade from trees at first glance may seem like a great place to plant shade-loving plants. However, many gardeners are skeptical and wonder if it is OK to plant hostas under trees?

Hostas are good under trees. To be successful, dig a hole under a tree by slightly pruning the roots of the tree. Plant only large hosta varieties. Be sure to mulch and fertilize the hosta after planting.

Are Hostas Good Under Trees

Plant only under the right trees

Maples Not recommended. Maple roots are very aggressive and it is almost impossible to grow other plants under their canopy.
Willow Not recommended. Willows have thin roots that form a dense carpet. In addition, these plants quickly dry out the soil around.
Walnut Not recommended. Walnut releases a toxin (juglone) that can cause significant damage not only to hostas but also many other plants.
Oak The superficial roots of oak do not interfere with the growth of other plants around. However, to grow hostas in such conditions requires additional care.
Conifers (Pine, Spruce) There are many examples of the successful cultivation of hostas under coniferous plants. This is especially true of pine, which has a suitable crown shape.

Some trees are better suited for planting under them, and some are not suitable at all. The fact is that the roots of trees will compete with the roots of the hosta, and in most cases, the hosta loses the competition.

Most trees have a superficial root system, and almost all of their roots are at a depth of 14-16 inches (35-40 cm). However, the roots of some trees are less aggressive, and under them, you can grow other plants.

All types of maples and especially Silver maple, have very fibrous and dense roots. Therefore, I do not recommend planting hostas under these trees.

Exceptions may be Red and Japanese maples whose age does not exceed 6-7 years. Under young plants, you can successfully grow plants for several years without harming them.

However, if the maple is mature and has a significant size, the plants under it will not grow.

You can dig a hole and cut the maple roots and then plant hostas there. Within 1-2 years, the hostas will grow quite well. But the roots of the maple will grow quickly enough and begin to suppress the hostas.

In the third year, the hostas will begin to decrease in size. And in the fourth or fifth year, it may not appear at all. In this case, neither additional watering nor fertilizer will help.

Oak and conifers are those trees under which you can successfully grow hostas. Of course, they will not be as big as if they grew in a more suitable place. Also, in these conditions, the hostas will need special care, which we’ll talk about later.

Remember a simple rule: the younger the tree, the easier it will be to grow plants under it.

Deal with roots

Before you start planting, you need to know a few rules on how to deal with tree roots.

The first case is when you plant hosta under a young tree aged 5-8 years. The roots of such trees are not too big yet, so you should be careful not to damage them.

Step back from the trunk no less than 1 foot (30 cm) and then start digging, if possible, use a plastic tool for this.

Dig carefully so as not to damage the roots. This is especially true of thick roots.

For planting under young trees, it is better to choose hostas that grow in small pots. This way, you do not have to dig a big hole, and as a result, you injure fewer roots.

Under such conditions, the hosta can be successfully grown for years until the tree becomes very large.

In case you plant shade-loving plants under old trees with a thick trunk, then you will have to work a little.

First, you need to step back from the trunk at least 3-5 feet (1-1.5 meters) depending on the size of the tree.

The second thing to do is dig a hole and cut off part of the tree roots.

According to scientific studies, many trees can withstand damage to 10% of the root system without serious consequences.

Dig a hole twice the size of the root ball. Use a sharp knife or shears to trim all the roots. Do not touch roots that are thicker than half an inch (1.2 cm).

The bigger the hole you dig, the better the hosta will take root there, and the longer the tree will restore its roots.

When planting under old trees, choose hostas that grow in big containers, i.e., have a large rhizome. This will help them establish faster and make it easier for them to compete with tree roots.

If you have dug a hosta in your garden and want to transplant it under a tree, try not to damage the rhizome. Also, do not divide the hosta before planting under a tree.

Plant the rhizome undamaged; this will allow the plant to take up more space faster.

Here is a little trick that can make it easier for hostas to live under a tree. Each year, use a shovel to cut the roots of the tree around the bush.

Just stick a shovel a few times around the hosta at a distance that spreads the leaves. At the same time, try not to damage the roots of the hosta.

Plant only vigor varieties

The next recommendation is to plant only vigorous, fast-growing varieties under the trees. Due to this, the hostas will be able to occupy a lot of space in the ground, and the tree will be difficult to deal with them.

Large and medium varieties are best suited for this:

  • Sum and Substance
  • Frances Williams
  • Blue Cadet
  • Cross Regal
  • Green Fountain
  • Elegance

Of course, their growth rate will be slower, but they will live.

Varieties that grow slowly are unlikely to live long in the shade of large trees. I do not recommend planting the following hostas in such conditions:

  • Blue Angel
  • Mouse Trap
  • Francee
  • Cherish
  • Sagae
  • Fortunei
  • Blue Mouse Ears

It is also not worth placing near trees varieties in which most of the leaves are variegated, ie, has little green pigment and instead a lot of chlorophyll-free tissue. Such plants are quite weak and will not survive under the pressure of tree roots.

Dwarf and miniature varieties are also better not to place under trees because they do not have enough strength to compete with a large tree. The same applies to hostas that are difficult to grow (rare varieties).

Water hostas properly

Proper watering is one of the key points in successfully growing hostas under trees.

The fact is that the trees form a canopy, and rainwater falls to the ground under the tree in smaller quantities. Add to this the fact that the tree sucks a lot of water from the soil, and as a result, you get a dry shade.

Hostas do not like dry soil, so you have to work hard to give them enough water. In the first months after planting, check the soil moisture, and as soon as it dries to half an inch, immediately water.

The amount of water will be greater than for watering hostas in normal conditions because part of this water is taken up by the tree. Large varieties may need four or more gallons of water per watering. Three gallons will suffice for medium-sized hostas.

The frequency of watering will be different. Sometimes you have to water every two days if the weather is too dry.

It should also be borne in mind that even if a little rain has passed, you still have to water the plants because the branches and leaves of the tree will not allow all the water to fall to the ground under. As a result, the land will remain dry.

Given all the above, the best solution is to install a drip line. If you do this, then you will not have to spend time watering.

Drip irrigation can also be equipped with a controller and a rain sensor.

Mulch your hostas

The next step is mulching. You need to pour mulch around the hosta to keep as much moisture in the soil as possible. This will also reduce the frequency of watering.

Organic matter is best for mulching. If possible, use compost. In this case, in addition to moist soil, you will also receive additional nutrition for your plants.

Here are a few words about compost. Choose only quality compost from reliable manufacturers. Do not use material from unknown suppliers as improperly made compost may contain aggressive substances that will harm the hostas.

Another good mulching material is pine bark. It also keeps moisture in the soil and lasts longer than compost. However, the nutritional value of such mulch is minimal.

Pour a layer of mulch 1-2 inches thick. A thicker layer will prevent air from getting to the ground surface, and a thinner one will not hold moisture well.

Mulch should be around each bush and cover an area slightly larger than the size of the hosta.

Do not pour mulch on the stems. There should be a gap of at least one inch between the base of the stems and the mulch. The same goes for a tree trunk, but here the gap should be larger (3 inches or more).