When a new gardener asks me what they can do to take their skills to the next level, I always tell them they need to learn how to read their plants. Now, I know how vexing that advice can be. I was on the receiving end of that advice for one too many years. Between times freaking out that I ruined my crops to days where I slowly watched my houseplants die, I was convinced I would never have a green thumb.
But those days are long gone, and I’m making it my goal to help others out. So, from keeping the alluring houseplant alive to the veggies in your garden making all your neighbors green with envy, here’s what your plants are trying to tell you.
Thin, Spindly, and Stretching
Most Likely Culprit – Light Stress
If young plants or new growth looks spindly, leggy, and is stretching to the point the stems can no longer bear their weight, it’s likely your plants aren’t getting enough light. These symptoms are fairly dead-giveaways, but you can also confirm low of light by looking for yellowing bottom leaves and the plant growing aggressively in the direction of its lighting source. If plants are still overstretching after receiving adequate light, you’ll want to look into DIF for help controlling plant stretching.
Most Likely Culprit – Water/Irrigation Stress
If your leaves are drooping but look plump, you’ve likely overwatered. If they are drooping but wilted and lifeless, then you are likely underwatering. In either case, the first thing you do is pick up your plant’s container and get a feel for its weight. Different plants like various amounts of water, and by lifting their pots when you see a drooping problem, you’ll be able to tell how much each plant likes.
When you’re having issues with watering, my advice is to pick up your plants’ pots every day to get a feel for their weight while also taking note of leaves. A well-watered plant will most likely have vibrate green leaves that bounce with life and appear full of vigor.
Most plants do best when you water until about 10-30% runoff. But if you have a small plant in a large container that might lead to overwatering. In this case, I like to imagine that the size of the root mass is around the size of the foliage above and I need about that much area of water. Remember, to water around the roots along and not solely on them to promote the best growth.
Leaf Drop And Slow Growth
Most Likely Culprit – Environment Stress
Plants that appear to stop growing overnight, throw out random blemishes, or suddenly lose leaves, are indications it has been stressed. In most cases, the best source of action is an attempt to indicate the stressor, remove it, and wait for the plant to recover. Everything from too much to not enough water to temperature fluctuations to transplanting can cause a plant to hunker down for a bit to recover.
Nutrient toxicities and deficiencies can be culprits as well but develop and affect the plant slower. In particular, a nitrogen deficiency can cause slow growth and yellow lower leaves that eventually fall off, while a phosphorus deficiency can stunt fruit development.
Necrosis, Rust Spots, And Other Plant Blemishes
Most Likely Culprit – Fertilizer Stress
Have leaves that are too dark green and yellowing? Are the tips of your plant’s leaves turning brown? Suspect overfertilization or nutrient lockout is the issue, but changing the amount isn’t helping? Well, then likely many, your real issue is a salt build-up.
Once you see it, you’ll never be able to avoid it. Next time you’re in a garden store, take a look at the containers, and you’ll see a white film coating the bottom and lower sides of many of the plant containers. This is almost always salt — in rare cases, powdery mildew can be the culprit.
The fertilizers we give our plants are salts that dissolve, delivering all the goodies we want them to have — like nitrate and phosphate. To ensure unused salts don’t build up in our media and only on the outside of the container, for soil and container grows, we water until we get suitable water runoff and for hydro we regularly clean the reservoir.
When a plant is showing symptoms of overfertilization, it’s not always due to the uptake of too much fertilizer. In fact, plants, to a degree, can pick and choose which nutrients they need from their medium. Instead, a media highly concentrated in salts, whether due to over-fertilizing or poor watering practices will burn root hairs. When this happens, the plant will pull resources from the foliage above to recover, resulting in leaf necrosis, yellowing, and spots.
Watering until runoff, using a single all-purpose fertilizer at lower concentrations, and ensuring temperature, humidity, and lighting amount are in check order will go incredibly far in preventing and correcting necrosis, rust spots, and other plant blemishes — even when there is only one nutrient that’s causing the problem.
While likely advantageous to diagnose which nutrient is causing the said problem, it’s often not required when following the above advice. Many nutrient toxicities and deficiencies look similar, especially to those new growers. Nutrient synergy and antagonism, location of plant issues, understanding environmental stress, and watching how a plant’s appearance reacts with different irrigation practices all take time to learn. Trying to properly diagnose an issue without knowledge of just one of these can’t do more harm than good.
Yellowing Leaves – All Of The Above Stressors
Most Likely Culprit – Any Of The Above Stressors
Yellow leaves are a delight for gardeners everywhere. They may indicate a plant’s maturity or can be caused by any of the stress factors we talked about above — oh, joy!
Leaves that are yellowing at the top of the canopy likely indicate they are receiving too much light. If the leaves are pointed upright or praying in addition, then too much light is almost a certainty. A zinc, manganese, boron, iron, or calcium deficiency can also be the culprit. These deficiencies are all fairly rare besides calcium when feeding a balanced one-and-done fertilizer. To confirm suspicions of a calcium deficiency, look for brown and orange freckling on the yellowing upper leaves.
Yellowing leaves only in the middle of the plant are generally rare, with moisture stress being the likely culprit. Pale green leaves with dark green veins may indicate a magnesium deficiency. Last, a severe nitrogen deficiency can cause yellowing leaves in the middle, which can be confirmed if the leaves below have yellowed first.
Yellowing leaves at the bottom usually means your plant needs a boost of nitrogen or isn’t getting enough light. A few yellowing leaves that eventually drop can be a sign of age as well, and usually don’t require attention unless it increases. If you suspect nitrogen is an issue and aren’t using a phosphorus-heavy flowering fertilizer, simply increasing your regular fertilizer instead of just nitrogen often offers better results. Plants that are frequently underwatered can suffer from yellowing leaves on all parts of it.
Putting It All Together
Beyond the tips above, I want to give you some personal gardening tips that really help me. First, the K.I.S.S method or Keep It Simple Stupid is wonderful advice to follow no matter your experience. It’s so easy to get in over your head with amazing equipment and advanced growing methods. But you will truly be surprised at the quality and yield you can pull from your crops when you grow with the tools that have been used for centuries. Even better, when you keep it simple, it’s easier to figure out what you do and don’t need when improving your personal garden.
But that brings up my second advice, and that is to spoil yourself with upgrades, etc. when you think it can help you out. For many, this is a fun hobby, and if that’s you, you don’t want it to be stressing you out because you’re working with less than ideal equipment. Don’t be afraid to look professional!
Last, don’t give up when your first plant, or even your second or third, doesn’t go great. When I felt I couldn’t even grow one plant species, the last thing I thought was that it would be smart to grow other crops. But it was just that, that unlocked my green thumb. So if you haven’t, try a microgreen garden — they’re simple, you learn a lot, and they are rewardingly tasty.