Question: How, when and why should I side-dress my plants with fertilizer?
Answer: "Side-dressing" refers to giving growing plants, especially vegetables, an extra dose of fertilizer, beyond whatever food you may have applied when you planted them. It is important if your soil is poor or sandy or you have just begun to improve it by adding organic matter. Side-dressing keeps plants growing well and can result in a better harvest.
Crops that most benefit from side-dressing are corn and onions. Legumes, lettuces and root crops such as carrots and beets generally don't need it. Others such as tomatoes, broccoli and peppers may appreciate it.
When to side-dress:
Tomatoes, peppers and okra: when they bloom.
Cabbage, broccoli and cauliflower: when heads begin to form.
Corn: when plants are knee high and when silk begins to show.
Onions: when plants are 6 inches tall, continuing every few weeks until bulb begins to swell.
Cucumbers, squashes and melons: while plants are still small and not yet spreading.
How to side-dress:
Side-dress individual plants by digging a shallow trench around each plant, about 6 inches from the stem, applying granular fertilizer and covering it. If you are working with a large plant or a shrub, dig the trench under the drip line (the outermost leaves). Water.
To side-dress a row of plants, dig a shallow trench about 6 inches from the row, down the whole length. Put in granular fertilizer and cover it. Water the plants.
For fertilizer amounts, follow the package directions.