Your begonia plants are hungry and need fertilizer to give them the extra nutrients they need. Since begonias are pretty sensitive to chemical burn or nutrient burn, it’s important to know which fertilizer to use for your plants to give them what they need—and how to apply it.
The first thing you need to know is that even though many plants can handle foliar feeding, begonias can’t because they don’t like moisture on their leaves and flowers. Having water beads, even if there are nutrients in it, on the leaves will cause stem rot or weaken the foliage to fungus attacks. For this reason, keep the fertilizer on the ground, not on the plant.
The next thing you should know before you decide which fertilizer to use is that begonias are generally happier with organic fertilizers than with chemical ones, but it doesn’t necessarily mean that they can’t handle chemical fertilizers. Your best bet is to test a little of each on your plants, but before you do, remind yourself about how sensitive and susceptible begonias are to chemical and nutrient burn. Because of this, you must dilute the fertilizer further than most directions will tell you. For instance, if you buy some fertilizer and the package says to use 1 tbsp. in your dilution, you should reduce it to 1 tsp. instead.
Finally, before you choose your fertilizer, know what the numbers on the fertilizer mean. Usually they’re in sets of three, for example, 1-1-1. These numbers stand for nitrogen, phosphorous, and potassium. Nitrogen aids in foliage growth, while phosphorous is for root development. Potassium helps the plant in using trace elements, thus rounding out the fertilizer. Some fertilizers have different numbers and trace elements, so make sure you’re reading your labels before you buy it.
Be Careful About Nitrogen
Now that you know about how fertilizer works and how it’s applied to the begonias, it’s time to discuss which fertilizer to use. The best fertilizer is one in which the number representing nitrogen isn’t higher than any of the other numbers, because begonias don’t really need help in developing leaves, and the nutrient burn that can occur from giving them too much nitrogen can actually harm them more than help them.
The top recommended numbers for a begonia fertilizer are 14-14-14, or 14-14-16. Remember always to dilute this type of fertilizer further than you would for any other part of your garden, so as to protect your begonias.
Slow-release fertilizer is best for begonias because it helps to maintain consistent nourishment. If you sprinkle some diluted fertilizer like this over the ground above the begonia’s roots on a regular basis, you can be providing your begonia plant with enough nutrients to weather through the entire blooming season.