Hostas are vigorous plants that can grow in a wide range of conditions. However, difficulties can sometimes arise in this regard.
The main reason why the hosta does not grow is that the crown is damaged by voles. The second reason is nematode infestation. In both cases, the approach to solving the problem is quite different.
Of course, these are not all the reasons why a hosta may not grow. Below we will look in detail at all the possible causes of a hosta not growing and how to fix them.
Voles and some other rodents very often damage the rhizome of the hosta. They methodically devour the underground part of the plant.
This can last a long time, and all the while the top part of the crown may remain green and healthy-looking. However, you may notice that the hosta is no longer growing in width or height. Also, no additional buds appear in the spring.
Only when there are too many pests and they destroy almost all of the rhizome, the leaves will start to turn yellow and the petioles may fall to the ground. Also, a clear sign of voles in the garden is holes in the ground.
To get rid of this pest, sprinkle pepper flakes around the hostas. This will help a little but it will not solve the problem completely.
The second thing to do is to pour an aqueous solution of castor oil into the soil around the hostas. Dilute a third of a cup of soap in five gallons of water and then add three cups of castor oil. Shake the mixture well and pour at least 1 gallon around each hosta.
This is a very effective way to control voles and other rodents in your garden.
Not enough water
Hostas are the kind of plants that prefer slightly moist soil to dry soil. They can tolerate short periods of drought, but if there is no water for a long time, the plant will suffer.
If, for example, your hosta is growing in sandy soil and in a dry place, it may not get enough water all the time. This does not mean it will die, but it will grow very slowly or stagnate. This often happens during the summer heat and lack of rain.
A clear sign that your hosta is not getting enough water is if the leaves are discolored or pale. In some cases, a yellow tinge may appear on the leaves.
To avoid this, keep an eye on how moist the soil around your hosta is at all times. As soon as the soil is about 2 inches dry, water each hosta with at least 1 gallon of water. This is especially important in the summer or if you have sandy soil.
Hosta Virus X is one of those diseases whose symptoms are not noticeable in the first 1-2 years after infection. Instead, you may notice that your hosta grows much more slowly than others or has stopped growing altogether.
In the second or third year after infection, you might see pale green spots on the leaves that increase in length between the veins. At the same time, the veins and the thin part of the leaf around them may remain green for a long time, but they will get smaller each year.
Usually, Hosta Virus X plants are infected in nurseries. From there they can enter gardens, where they show symptoms.
If you suspect this disease, buy an HVX test kit and use it as directed. If your hosta is infected, carefully dig it out and throw it in the trash. There are currently no effective treatments for Hosta Virus X.
Read more about this in the article: Hosta Virus X
In general, hostas are not too picky about soil. They can grow in relatively poor or clay soils. However, in this case, you should not expect them to grow vigorously.
Also, if the soil is too alkaline or too acidic, it can cause problems with the assimilation of nitrogen or phosphorus. This in turn will slow or stop their growth. Moreover, it can lead to worse consequences.
To correct this, first, check the soil pH with a test kit you can find at garden supply stores. If soil pH>7.3, add sulfur or another acidifier to the planting hole. If soil pH<5.5, add some garden lime to the soil.
If your soil is nutrient-poor, heavy, or poorly drained, add 1-2 buckets of compost to the planting hole. Mix the compost well with the native soil before planting the hosta.
In this case, by crown rot, I mean several different diseases that can damage the crown, roots, or stems of the hosta. They all develop at different rates. Some can kill a hosta in a few weeks, while others can last the whole season.
Some diseases can be overcome by the hosta itself. However, the plant will not grow normally during this time. The healing process can take a whole season and the hosta will not increase in size.
To avoid this, you should not over-water your hosta. Only water when the soil is more than 2 inches dry.
Avoid planting hostas where water accumulates. For example, too close to a gutter or near ponds.
Also, improve your soil if it is poorly drained. You can do this by adding compost or soil conditioner to the native soil.
Nematodes are quite insidious pests of hostas because they are invisible to the human eye and multiply very quickly. They usually live in damp places and when the growing season arrives, they penetrate the hosta’s tissues and destroy it from the inside.
As a result, the hosta is severely stunted or it may stop growing. But there may be no outward signs of the pest.
In the first few years, you may not even notice the presence of nematodes. As long as their numbers are small, they are not capable of causing serious damage to the hosta. However, when they are abundant, brown streaks between the veins will form on the hosta.
To control nematodes in the garden, soak the soil around each hosta with a 10% aqueous solution of ammonia. Also nematicide works well against this pest.
Read more: How Do You Treat Hosta Nematodes?
The next thing that can prevent hostas from growing is slugs. They are very fond of eating young leaves, which can cause a lot of damage and stress to the hostas.
A symptom that indicates the presence of slugs is holes in the leaves. They usually eat the space between the veins. These creatures are most active in humid and warm weather.
To solve this, drench the soil around each hosta with ammonia diluted in water. Dilute the ammonia at a ratio of one to ten (ammonia:water). This will kill any eggs that are near the hostas.
The next thing you need to do is put some iron phosphate granules between the bushes. This will get rid of all the adult slugs.
And the last reason a hosta may not grow is frost damage. Sometimes a late frost can occur in mid-spring when the hosta begins to unfold its leaves. As a result, the leaves will be damaged and it may take a long time for the hosta to recover.
In some cases, the hosta may not grow for an entire season after spring frost damage. But that doesn’t mean it’s dead, it just needs time to recover.
To avoid this course of events, watch the weather forecast in the spring. As soon as you hear that a frost is approaching, cover your hostas for that time. You can find plenty of good covering material for this purpose on the market.
I wrote more about this in an article: Can Hostas Survive Frost?