Causes of Wilt

• Plants wilt when they cannot take up enough water from the soil to replace the water lost from their leaves through transpiration. Water normally fills storage structures in the plant's cells, keeping them firm and helping the plant to hold its shape. When the plant loses water, the cells lose this firmness and the plant wilts.
  
  Lack of water is an obvious cause of wilting. However, too much water -- which cuts off oxygen to the roots and interferes with healthy root function -- can cause wilting as well. Too-high or freezing temperatures, soil compaction, fertilizer salts, damaged or circling roots and insect or disease problems can also cause plants to wilt.
  
  

Diagnosing Wilt

• If your vegetable garden is uniformly wilted, you can likely rule out pest or disease problems, which rarely affect multiple types of vegetable plant. Check the soil moisture first. If you dig down an inch below the soil and don't feel any moisture, your plants would likely benefit from a good, thorough watering. If you observe standing water in your garden or know that plants have recently received abundant rain or irrigation, the soil may be overly wet. This can especially become a problem in heavy clay soils, which drain very slowly. If you're growing vegetables in containers, make sure the containers have drainage holes at the bottom, as overwatering in poorly drained containers is a common cause of plants wilting.
  
  If moisture levels seem normal, consider other factors. Shallow cultivation for weeds, recent fertilizer application, or hot or cold weather can all damage root systems and cause plants to wilt.
  
  

Fertilizer Purposes and Uses

• Even if fish-based fertilizers won't relieve wilting, they provide other benefits to your veggie plants. Fish emulsion and fish meal are organic fertilizers that provide about 4 to 5 percent nitrogen. Fish emulsion also provides 1 percent each phosphorus and potassium, and fish meal contributes 3 percent each phosphorus and potassium to your soil. These 3 nutrients are essential for healthy plant growth, especially for heavy-feeding vegetables like tomatoes.
  
  

Nitrogen Fertilizer Caution

• Because fish-based fertilizers primarily add nitrogen to your soil, you should use care when timing applications on your vegetable garden. Nitrogen encourages the growth of stems and leaves, often delaying flowering and fruit production. If you apply nitrogen within a few weeks before the production of flowers, you may delay the generation of veggies on plants like tomato and pumpkin. Phosphorus-rich fertilizers enhance flowers and fruits.