How to "Read" Your Plants and Prevent Problems in the Garden

Do you understand plant language?

Though they can’t speak, plants send messages all the time — from requests for resources to warnings of trouble.

And they do so silently, communicating with visual cues, such as altered leaf colors and shapes.

If you learn to read these signs, you’ll be able to catch minor issues before they become big problems, thereby maximizing the productivity of your garden.

So here’s a lesson in plant language 101.

Quick Reference Guide to Secret Plant Signs

If you notice a problem in your garden, but are short on time, use this chart to narrow down the possibilities.

Tower Tip: Nutrient deficiencies, plant diseases, and other problems can occur at the same time and look similar. So identification may be tricky. If you need help, take a sample of the affected leaf to your local cooperative extension office.


(View a larger version)

Want to learn more about what your plants are trying to tell you? Let’s dive a little deeper…

Yellow Leaves and Nutrient Deficiencies

"Why are my plant’s leaves yellow?"

If you’re like most gardeners, you’ve faced this befuddling question before. Leaf yellowing — known as "chlorosis" in the world of science — has many potential causes. But one of the most common is undernourishment.

For healthy development, plants require 16 different micronutrients and macronutrients. And if they don’t get them or if proportions are imbalanced, leaves may start to look strange, become more susceptible to disease, and slow (or even stop) their growth — decreasing yields.

Symptoms of Plant Nutrient Deficiencies

Before you can address a deficiency, you’ve got to be able to figure out which nutrient your plant needs. So here are a few ways a plant may show you it’s missing something important:

  • Boron – Young leaves turn light green and may be disfigured.
  • Calcium – Leaves are disfigured and may wilt or show signs of necrosis (i.e., death of plant tissue).
  • Copper – Leaves may be limp and/or curled.
  • Iron – New leaves turn a pale, yellow color between green leaf veins (this is known as interveinal chlorosis).
  • Magnesium – Leaves show spotting and yellowing between green leaf veins. Outer edges of leaves may pucker or curl.
  • Manganese – Younger leaves turn yellow between veins (giving them a net-like look) and may develop dead spots.
  • Molybdenum – Older leaves yellow. Remaining leaves turn light green. All leaves may become distorted and narrow.
  • Nitrogen – Older leaves and veins turn a pale, yellow color. Other leaves turn light green and stay smaller than normal.
  • Phosphorus – Leaves looks stunted and turn dark green or even a deep purple color (almost black for some plants). Leaf tips may look burnt.
  • Potassium – Older, lower leaves show marginal necrosis, even looking scorched around the edges. Leaves also yellow on edges and between veins.
  • Sulfur – New leaves yellow and leaf veins lighten while older leaves remain green. (May be confused for a nitrogen deficiency.)
  • Zinc – New leaves yellow and may develop necrosis between veins.

For further help with identification, check out this visual representation of deficiency symptoms.

How to Fix Nutrient Deficiencies

The best way to solve deficiencies is to avoid them in the first place by giving your plants the nutrients they need.

For soil-based gardeners, that means using fertilizers, rich compost, and other amendments. But if you’re growing with Tower Garden, all you really need is Mineral Blend — a simple, balanced mix of all the key nutrients.

Tower Tip: Even if you’re providing the essentials, a high or low pH may keep plants from absorbing or processing them. Most plants access nutrients best when pH is around 6.5. So measure your levels every few weeks and adjust as necessary.

Other Causes of Discoloration and Disfigurement

Nutrition isn’t the only reason a plant’s leaves may look unusual. Here are a few other common causes.

Pests and Plant Diseases

It’s wise to watch for garden pests. Because bad bugs not only damage and stress plants — they also often introduce the following types of plant diseases, which bring additional harm:

  • Bacteria – Bacterial diseases can cause wilting and spotting.
  • Fungi – Some leaf fungi mimic certain symptoms of nutrient deficiencies, including yellowing and necrosis.
  • Virus – If you see blotchy or patchy yellowing on your leaves, a virus may be the responsible (especially if the discoloration is accompanied by disfigured growth).

Learn how to prevent and control these diseases »

Over (or Under) Watering

One of the most common, non-nutrient-related causes of yellow leaves is over or under watering. It’s a common cause, that is, for soil-grown plants.

Since Tower Garden automates the watering cycle, plants always receive the optimal amount of water. But if you’re growing in soil, here are a couple of ways to determine whether you should adjust your watering schedule:

  • Check the soil. (I know — it’s basic. But it’s never a bad idea.) If it’s drenched, it may be waterlogged, robbing plant roots of the oxygen they need to survive. In this case, water less.
  • Look for dropped leaves. Plants that don’t receive enough water drop leaves to prevent transpiration (i.e., the evaporation of water from plant leaves). So if you see leaves on the ground, water more.

Environmental Factors

Your growing environment can impact how your plants grow. Here are a few elements to consider.

Light
When accompanied by thin, reaching stems, pale leaves usually suggest a plant isn’t receiving enough light. (Most plants need at least six hours of direct sun or, if growing indoors, 14 hours under grow lights.)

On the other hand, newly transplanted crops may develop bleached spots on their leaves after too much sun exposure. To avoid this, harden seedlings by gradually introducing them to the outdoors over the course of a few weeks.

Similarly, when growing inside, leaves that get too close to grow lights may become spotted or scorched due to over-transpiration, which is followed by yellowing, spotting, and, eventually, leaf death. The solution? Harvest more often!

Nutrients
To prevent wilting in a Tower Garden full of small seedlings (e.g., plants that are three inches tall or shorter), it’s best to use a half-strength nutrient solution: 10mL of Mineral Blend A + 10mL of Mineral Blend B per gallon of water.

You can safely increase nutrients to the full amount once seedlings have grown taller than three inches and developed a robust root structure. This usually takes less than a month.

Note: Even for mature plants, overly concentrated nutrients can also cause fertilizer burn. So make sure you’re always feeding your plants the proper amount.

Temperature
Extreme heat often causes plants to wilt. But they usually bounce back once temperatures cool. That being said, these precautions can help protect your plants from hot weather.

If you notice black spots on leaves or plants after a cold snap, frost damage is likely the cause. Some plants — particularly kale, collards, and other hardy greens — can survive light frosts. More sensitive crops, such as tomatoes and peppers, however, usually die after freezing weather.

Wind
If leaves look dry around the edges and/or curl upward, they may be suffering from windburn. Consider setting up a wind barrier to protect them.

Time
It’s completely normal for older, more mature leaves of a plant to yellow and die over time (as long as new, green leaves are replacing them). Just remove these old timers as you see them to prevent leaf fungi.

What Are Your Plants Saying?

Now that you know how to decode your garden’s secret language, diagnosing and rectifying problems should be a little more straightforward.

Have any questions or tips of your own? Let’s continue the conversation in the comments below.

Leave a comment

Want to leave a comment? We'd love to hear it. Please note that all comments are moderated. Anything resembling spam will be deleted. Try to make this a meaningful conversation for all involved.