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Why Are My Potato Plants So Tall

Even if you are an experienced gardener, every season can be different for plants. No matter if they are a brand-new plant you’re looking to try out or one you’ve planted, again and again, each year can bring along new surprises. Vegetables are more likely to have different growth patterns compared to plants. Habits like weather and watering can change how a vegetable plant grows in a given season.

If you have a smaller area for your plants, you may have to make every inch count. So not knowing how big or small a plant can grow may impact whether or not you can handle growing it. A plant that can often grow bigger than a gardener’s expectations is the potato plant. As the growing season continues, gardeners may wonder, “Why are my potato plants so tall?”

Potato plants tend to grow very tall when given an excess amount of nitrogen-based fertilizer.

Since you now know that too much fertilizer is why your plants are growing too tall, you may be wondering how much is the right amount of fertilizer.

How much fertilizer should I give my potato plant?

Potato plants only need around one-fifth ounce of total nitrogen for the entire growing season. Too much nitrogen is often why some gardeners find that their plants have grown exponentially. To ensure that you’re giving your plant that one-fifth ounce amount, try opting for a granular nitrogen fertilizer since it’s far easier to measure.

Beginner gardeners can find themselves being too attentive to their plants and ultimately missing out on a successful garden. Keeping an eye on fertilizer will help keep all your plants alive and well.

How much water should I give my potato plant?

Watering can also play a role in a potato plant becoming too tall. Potato plants need about one to two ounces of water per week. Remember that this would also include rainwater, so you may need to skip a watering if you have had a particularly hard rain.

Keeping the proper water amount consistent will help keep your plant at a reasonable size. Like fertilizer, it’s easy to overwater, so think about keeping a note on your phone to track how much water your plant has gotten throughout the week so you know when it’s time to water.

How tall should potato plants get?

According to the International Potato Center, typically, the usual height for potato plants is around 40 inches tall. If your plant is exceeding this height, be sure to consider exactly how much water and fertilizer you are giving it, along with the nitrogen content of the fertilizer. If your potato plant gets too tall, there is a risk that it could tip over, depending on the environment it is planted in. 

However, it’s important to note that when a potato plant is ready to be picked, it may start to topple slightly due to the fully grown potatoes in the base of the plant. It’s usually a safe bet that if your plant is very tall and it’s early in the season, you need to scale back the amount of fertilizer. If it is closer to the harvesting time, there is a good chance you have a solid round of potatoes waiting to be dug out!

Can I Trim The Tops Of My Potato Plants?

If you find that your potato plant is far too tall, it’s natural to wonder if you can trim it back so that it doesn’t fall over. You definitely can trim the top of your potato plant; however, there is one caveat. It is only safe to prune when the potato tubers (the parts of the potato plant that we eat) are set to be harvested.

If cut too early, you risk your plant not having enough foliage to get all its nutrients to produce viable potatoes. Don’t be afraid to go in and give your plant a trim; it may need it! Before you cut, think about your plant’s lifecycle and if its harvest time is approaching or not.

Final Thoughts

If you are looking at your potato plant and think it is looking like it’s a bit on the larger side, you may want to rework your watering and fertilizing schedule. A standard potato plant stands at about 40 inches tall, so if you measure and find that yours is much higher, it’s time to reevaluate things. 

One of the main reasons a potato plant becomes too tall is because it has been given too much fertilizer with strong nitrogen content. Most potato plants only need about one-fifth of an ounce for the entire season.

You’ll want to stop fertilizing altogether if you have already surpassed that. Similarly, if your plant is receiving, on average, more than one to two ounces of water per week, you will need to cut that back right away. Often, people forget to incorporate rainfall into their watering schedule, which quickly leads to overwatering. 

It’s also vital to note that if a potato plant has a relatively successful run, it may start to lean a bit as the base will be slightly off-balance due to the number of potato tubers in the bottom of the plant. If your plant is getting very tall and it’s almost time to harvest, it could just be that your potato tubers are ready and not that the water or fertilizer needs to be adjusted at that time.

Start by measuring your plant, analyzing your fertilizer and water schedules, and then switching up the plan depending on whether your plant is too short or tall. If your potato tubers are ready to be harvested, you can also consider cutting a bit of the top of the plant back to help keep it standing upright. Finding out what your potato plant needs in terms of water and fertilizer can differentiate between a thriving plant and a dying one.

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