we talked about water and soil type. These two subjects are important because ultimately, your scorched blooms boil down to a water issue. How you water, and what type of soil you have both affect how your plant receives its moisture to keep those beautiful, pristine blooms. In this segment, we will be diving deeper into the soil aspect, including the chemical makeup of your soil and how things you can’t even see affect how your rose gets its water!
Part 3: Fertilizer and the chemistry in your garden beds
In order to understand your soil’s chemistry, I will again recommend getting your soil tested. This is by far the easiest way to know exactly what your soil needs. However, I know a lot of us gardeners are stubborn or don’t want to spend money on a soil test (I‘d rather get plants, I know!), so I will explain more in depth. You should strive to have a loamy soil, as explained in part two, by adding in plenty of organic matter to your soil. Another thing that you HAVE to consider though is the pH of your soil. “Come on, what does pH have to do with my rose getting watered properly?”
Well, it all breaks down into the chemicals and minerals in the soil that your rose uses. Just like humans, we need lots of food and other supplements to make sure our bodies are working properly. Water, of course, is important, but so is food.
There are three main “foods” I will cover in this article, that roses depend on for proper growth and health. “But come on, everyone knows plants eat sunlight.” Yeah, but you don’t just eat protein right? You need carbs, sugars, starches, and lots and lots of micro and macro nutrients from veggies and fruits (and a few other foods!).
Plants need these three main nutrients to survive and thrive. If you’ve ever bought fertilizer, on the bag somewhere it will have a set of 3 numbers set up like so: 5-5-5 (or some combination of numbers). These refer to the three nutrients I will be covering today, in order: Nitrogen (N), Phosphorus (P), and Potassium (K). This is frequently referred to as the NPK.
Nitrogen is one of the most readily available nutrients out there. It is present in rain water, and frequently becomes available as microbes break down composts and other organic matter. It also is the easiest nutrient that is “leached”. A leached nutrient just means it gets carried away- it doesn’t just sit in the soil until the plant is ready for it. Typically water carries nutrients away from plants. Nitrogen can become unuseable in low pH soils, or acidic soil.
Nitrogen is important to plants for many reasons, but mainly, nitrogen is the component that causes leaf and stem growth. Nitrogen is what makes your plant grow! You can tell if you have a nitrogen deficiency by looking at your leaves and stems. Nitrogen deficient plants have weak, spindly stems AND yellow or pale green leaves, starting from the base of the plant and working its way up the stems. Be careful not to confuse these symptoms with other things. Spindly stems are also common on young plants, and yellowing leaves can also be a symptom of under watering or blackspot.
Phosphorus is an extremely important element. This nutrient can be bound up, or rendered unusable to the plant, in acidic AND alkaline soil. This is a reason knowing your pH is so important. If you have too low or too high of a pH, your rose can‘t use this important nutrient! This is also a nutrient that is fairly rare in nature. A study has shown that out of all the phosphorus in nature, only about 0.1% of it is available for plants to use!
Phosphorus is responsible for several things in a plant. It helps create robust root systems, it helps increase fruit set (which in flowers is flower production!), it helps plants photosynthesize, it helps with respiration (the carbon cycle which provides fresh air for us humans), and, most importantly to the topic of our blog this week, it helps plants regulate and efficiently use water! This little mineral does a lot!
Your plant might be phosphorus deficient if you notice weak root systems, lack of blooms, wilting and scorching on your plant, as well as leaves darkening and burning at the tips and edges of the leaves. Older leaves may turn a dark blueish-green color and lose any sort of shine they may have had.
Potassium is another very important nutrient for plants. Potassium can be bound up in low pH (acidic) soils. In most soil in general, potassium is present in large amounts. However, it’s usually in a solid form or bound to heavy clay particles, making it yet another nutrient that plants have a hard time getting!
The most important role that potassium does is it is a key component to the health of your plant. Plants that lack proper potassium become more susceptible to diseases and pests. Potassium also controls how well your plant can handle extreme temperatures, such as extreme heat and drought, as well as extreme cold! Potassium is also important because it helps the plant do several key activities. It helps plants metabolize their food and nutrients, as well as their water levels and other nutrients. So without potassium, your plant can’t use the nutrients it has access to, or the water! This is another key reason your blooms may be scorching in the heat. Think of potassium as the nutrient that regulates all other nutrients.
Your plant may be deficient in potassium if you notice scorched blooms and leaves, weak stems, and heavily affected by pests and diseases. This can be characterized on the leaves as burned edges and pale, yellowing leaves.
A few other key nutrients I won’t dive deep into, but want to touch on is iron and manganese. Both of these, along with phosphorus, get bound up and become unusable in high pH (alkaline) soils. I am mentioning this due to our area (DFW Metroplex) typically having high pH soil.
Iron is important to your plants for a very simple reason- it’s the main nutrient that produces chlorophyll in your plants. This is the nice green of the leaves that allows plants to soak in sunshine and turn it into energy. Without iron, your plant struggles to have proper energy and to respire. Iron deficiency is the easiest and most recognizable. Your plant will have yellow leaves, with the center “veins” of the plant remaining green. It will almost look like a skeleton. Typically if your plants are showing an iron deficiency, you use a supplement that adds iron to the soil. However, if you live with high pH soil, you may have plenty of iron in the soil, but your pH is too high for your plant to access it. If this is the case, you want to use a soil acidifier to help release the iron. You can also do a foliar spray of iron for a quick relief.
Manganese is a micronutrient, meaning your plant doesn’t need very much of it. It is key to several functions in your plant though. It helps with photosynthesis and chlorophyll production, as well as metabolism and cell division. Manganese deficiency causes the same issues as iron deficiency- lack of chlorophyll, which means your plant can’t eat. It also presents itself in a similar fashion, with yellow leaves and green veining. Manganese deficiency is not very common except in high pH soils, and lowering the soil pH will take care of it. Be careful with manganese, as plants only need very little of it. I do not recommend supplementing anything special for this, as most fertilizers have a tiny bit and will take care of the issue with regular fertilization.
So to recap the affect Ph has on your plants:
Acidic (low pH)- binds nitrogen, phosphorus, and potassium
Alkaline (high pH)- binds phosphorus, iron, and manganese
Phosphorus and potassium have the greatest impact on your roses during the summer, and can directly contribute to scorched blooms, no matter how much you are watering.
We must also consider your soil type when talking about nutrients as well. Sandy soil tends to have less nutritional value in it, and leaches nutrients very quickly due to how well draining it is. (Again, water is the most likely cause for leaching of nutrients. That’s why fertilizing in pots is so important!) Clay soil can hold onto phosphorus and potassium in particular, making them inaccessible to your plant. Loam soil is ideal because the organic matter helps provide almost all of the nutrients needed as it breaks down, as well as holding proper amounts of moisture, reducing leaching, and not binding the nutrients.
As you can see, if you followed and read all three blogs, there are so many factors that can contribute to your blooms scorching. This advice goes for many other plants too, not just roses. To avoid scorched blooms, try to get your soil closer to neutral pH. Add plenty of organic matter, and make sure you are watering deeply to encourage deep roots that can search for more nutrients and water. Make sure you are adding the nutrients that your specific soil needs, as not all soils have the same components. Using a fertilizer that is higher in phosphorus and potassium (?-P-K) is generally a good practice, as these two nutrients are important and hard to find for your plant. For liquid fertilizer we generally use the organic Alaska brand fish fertilizer and MorBloom. Combined together the are 5-11-11, which is an ideal combination and since it’s organic, you really can’t overdo it! Another thing to note with roses is that the petals themselves have lots of oils within. This is what gives roses their great fragrances. However, keep in mind what happens when oil is heated up. That’s right, it burns and fries stuff! Some roses have really thick petals that hold more moisture, and these roses will be less likely to scorch. Some roses have very thin petals. Sometimes, roses with lots of oils are the ones with the best fragrance, and lots of oils generally means more likely to scorch.
All of these factors are important to keep in consideration when asking, “What’s up with my blooms scorching?!” The answer is, there is many different reasons why they may be scorching, but you can have the best success by getting your soil tested, adding the necessary organic matter and nutrients, as well as pH adjustment if needed, and watering your plant deeply, a few times a week once they’re established. During the summer blooms will last a shorter period and may open up faster. That’s perfectly ok, that’s how the heat affects the roses! By following these tips, you are sure to see an improvement in the quality of your summer blooms. Keep in mind that fixing your soil takes time, and you may or may not see the results until next year, but it’s better to start right away with correcting what needs done!
I hope this miniseries has been helpful to you, and I hope that those of you losing your blooms to the heat feel hopeful! Until next time, see you soon!