NOTE: Cup plant may be referred to as Silphium perfoliatum in this article, in fact, those are the same plants, Silphium perfoliatum is the botanical name for Cup plant.
The cup plant (Silphium perfoliatum) is a perennial with coarse leaves that can be found in low woods, prairies, and meadow, and bordering streams or ponds. It’s an extremely hardy, low-maintenance plant that can survive in a variety of temperatures and locations, and has the ability to self-seed.
Why does my Silphium perfoliatum roots have rot?
Root rot on your Cup plant (Silphium perfoliatum) can be fatal if not treated with care. For this reason, we strongly recommend that you follow our guide to keep your plant alive if the symptoms occur: Root soft and blackened.
Why does my Cup plant have gray mold spots?
A particular fungus known as gray mold spots spreads quickly and frequently damages flowers. This fungus is probably to blame if you see any brown (or gray) spots. If you disregard these warning signs, your plant could die.
Our Solution
When you understand the root of the issue, the solution makes perfect sense. The majority of the time, it is caused by the Silphium perfoliatum being overwatered. We urge you to cut off the infected roots and leaves, remove the affected sections of the plant, and then repot your plant in a fresh container with sterile potting soil.
Why does my Cup plant have leaf spots?
If your plants exhibit symptoms like rapid color changes in the leaves or leaves that wilt or droop, we give you all the information you need to recognize them and rescue your plants. For owners of Cup plant, this kind of illness is among the most distressing.
Why are my Cup plant leaves turning yellow?
Yellowing leaves are arguably the most prevalent issue in the gardening world. Overwatering or a lack of nutrients are the 2 main causes of this issue.
Whether you think your plants are getting too much water, cut back on how often you water them, and take the following measures to see if they might be nutritionally deficient:
Each deficiency produces a different yellowing on the Silphium perfoliatum in question, here’s how to spot them:
- The first symptom of a magnesium deficiency is yellow patches between leaf veins on elder leaves. The leaf’s core turns yellow while the veins stay green. The edges of the leaf yellow last.
- Iron deficiency also shows as yellowing between leaf veins, but it hits young leaves on plant tops and branch tips first.
- The newest leaves are first affected by sulfur deficiency, rendering them completely yellow.
- Insufficient potassium causes the leaf edges to turn brilliant yellow while the interior of the leaf stays green. Older leaves show the symptoms initially, and the leaf edges quickly darken.
- A lack of nitrogen is indicated by a widespread yellowing. Older, inner leaves are the first to yellow. As the yellowing progresses, it eventually touches young leaves as well.
Our Solution
According to the symptoms mentioned above, you just have to act accordingly. You can reduce your watering frequency, or fix a deficiency in Potassium, or Nitrogen, for that, you just have to buy a special soil for your deficiency, a consultant in a gardening store will know perfectly well how to inform you.
Is my Cup plant sunburned?
It is simple to determine whether your Cup plant (your Silphium perfoliatum) has sunburn. Your plant will change color in this instance, beginning to turn yellow or white, much like it does on us.
As we saw above, the leaves of your Cup plant can also change color if it receives too much water or insufficient light.
The bottom of the yellow leaves with a shaded area closer to the base can be examined to determine if they have been sunburned. If this part remains greener, the yellow leaf is most likely sunburned and not something else.
Why are my Cup plant leaves turning brown?
The classic sign that a plant has been overexposed to direct sunlight and sunburned is the development of browning leaves. Rest assured that while this may probably save your plant from dying, it will adversely affect its growth.
Should I leave my Silphium perfoliatum in direct sunlight?
No! Don’t leave your Silphium perfoliatum (or Cup plant) in the sun if it displays the symptoms mentioned above; that’s why it’s in such a bad situation.
Our Solution
As explained in the paragraph above, the solution is simple, just place your Cup plant in a place where the light does not reach it directly, in this way and with a correct watering, your plant should resume its life rather quickly.
Why are my Silphium perfoliatum leaves drooping or wilting ?
In most cases, this happens when your Silphium perfoliatum lacks water. This is especially the case for large plants, naturally they need more water than others.
An easy way to know if your Silphium perfoliatum is lacking water is to under-weigh its pot, if it looks light, it means that the soil and the roots are probably quite dry, and therefore need water!
Our Solution
If the soil in your plant’s pot is completely dry, you will need to start by moistening it so that the roots will also benefit from the water. A common mistake is to drown the Cup plant right after a dry period thinking that it needs a lot of water.
This is true, but the easiest way to end it is to give too much water at once. Instead, you should water the soil properly, returning to a peaceful watering rhythm.
Caring Tips for Silphium perfoliatum
Water Occasionally
Water is essential to the survival of your plant, however, it is important to balance the rate of watering. As we explained above, overwatering could have fatal consequences for your Silphium perfoliatum.
Touching the soil will let you know whether your plant needs water or not; if it still feels damp, it’s generally best to wait a few more days.
Always keep temperatures stable
Maintaining a consistent temperature for your Silphium perfoliatum is also a good idea, especially if it is kept indoors. At GreenShack, we typically advise reserving a temperature between 65 and 85 degrees F. Of course, avoid positioning your Silphium perfoliatum close to air conditioners, radiators, or other sources of hot or cold air.
Keep your Cup plant Dust-Free
This one relates to indoor plants. Just like your furniture, dust collects on the leaves of your indoor plants. The issue is that this can block the photosynthesis process from starting, which would cause the plants to gradually lose their color.
For your Cup plant, this would be a true descent into hell, and it would also appease the pests.
To remove the dust from the leaves of your plant, take a microfiber cloth and gently rub the leaves. You can wet the cloth to make it easier to remove the dust, but never use corrosive products (such as rubbing alcohol!)
Keep drainage in mind
If you have a tendency to overwater, you need to keep an eye on your drainage, we advise you to opt for a pot with drainage holes if it is not already the case and a saucer.
If your pots don’t already have holes in them, you can add volcanic rocks (or any other pebbles with holes) to the bottom of your pot in the meantime. This will assist in creating a channel and keep the water from pooling there for an extended period of time, protecting the roots from decay.
