Debbie Roland, Master Gardener
If you grow plants in pots, fertilizing them is a must. Each time you water a container plant the nutrients are leached out of the potting mix. A plant that is in the ground has roots that grow and seek out additional nutrients, but a container plant is basically “quarantined” (a word we are way too familiar with now) from beneficial bacteria and nutrients in the soil.
Even with a high quality compost and/or potting soil, it only takes about six weeks for a plant to begin showing signs of needing help.
First, incorporate fertilizer pellets into your potting mix unless the mix already contains fertilizer. Some brands feed for 60 days and some for 120 days, so be sure to read the label so you will know when to begin adding nutrients. If you want to use an organic product, alfalfa pellets, cotton seed meal or fish meal pellets are some of the available choices.
Second, as your plants grow, add a liquid fertilizer as a supplement. They deliver nutrients directly to the roots and are easy to apply. Follow the directions for the amount for each plant and the dilution rate. If you are fertilizing fruiting plants such as tomatoes and peppers, pick a fertilizer that is high in potassium. If the plant does not fruit, use one with an equal ratio of N-P-K (nitrogen, phosphorus and potassium).
Finally, if you notice that your plants seem stressed, feed the plant directly onto the leaves with a spray bottle. Cut back dried or damaged foliage and spray water soluble fertilizer directly onto the foliage. CAUTION: Only do this when the temperature is below 90 degrees and the plant is not in full sun, such as early morning or late evening, otherwise the leaves will burn.
And since there is always an exception: Salad leaves (Lettuce, spinach, etc.) do not usually need additional fertilizer. Most herbs do not require fertilization either and do better in dry conditions with nutrient poor soil, especially rosemary and thyme.
If you have questions, please call the AgriLife office in Odessa at 498-4071 or in Midland at 686-4700 for more gardening information. Additional information is available at https://aggie-horticulture.tamu.edu and westtexasgardening.org