How to Fertilize for Strong Plant Stems
The soil nutrients nitrogen and potassium are responsible for healthy stem growth. Common nitrogen sources include blood meal and soybean meal, while granite meal or greensand contributes potassium. But too much fertilizer -- or fertilizer applied at the wrong time -- can have a detrimental effect on stem growth. The minerals, especially nitrogen, can cause stems to grow too rapidly if they are given in excessive quantities or just before cold weather, when new growth is susceptible to damage. Apply stem-strengthening fertilizers before planting your garden and midway through the growing season.
Remove any mulch, weeds or debris from the garden bed, if needed.
Sprinkle a blend of your chosen nitrogen and potassium amendments on the surface of the soil, at the rates recommended on the package for your square footage. In general, you need 2 to 3 pounds of nitrogen-rich blood meal, fish meal, soybean meal or cottonseed meal per 100 square feet. For potassium, add 5 pounds of greensand or granite meal per 100 square feet.
Till or rake the broadcasted amendments into the top 4 to 6 inches of your soil.
Plant seedlings or sow seeds at least two weeks after applying your fertilizer blend.
Side-dress plants with nitrogen and potassium fertilizer once or twice during the growing season, depending on individual plant recommendations. Lay a narrow band of your chosen dry fertilizers along the front of rows of plants or in a circle around individual plants. If blending the amendments, use twice as much potassium as nitrogen, which tends to be more concentrated.
Water the soil after side-dressing to encourage the absorption of nutrients.
Apply liquid fertilizer to plants as needed. Fish emulsion, for example, is high in nitrogen. Follow package directions for how much of the concentrated fertilizer to dilute in water, and then spray the fertilizer directly onto plant leaves and stems. Liquid fertilizer allows plants with poor stem growth to get immediate benefits from high-nitrogen solutions.
- Dry nitrogen fertilizer (e.g., blood meal or soybean meal)
- Dry potassium fertilizer (e.g., greensand or granite meal)
- Rake, spade or hand tiller
- Garden hose
- Liquid fertilizer (as needed)
- Spray bottle for liquid fertilizer (as needed)
- Don't apply dry or liquid fertilizer to perennial plants in fall or winter. Even in Mediterranean climates, new growth is susceptible to cold snaps.
- Don't assume "the more, the merrier," especially when it comes to nitrogen. Follow directions for the amount normally applied unless you have a known nitrogen deficiency in your soil. Excess nitrogen can cause excessive leaf and stem growth at the expense of strong roots or healthy fruiting and flowering.
- A balanced approach to nourishing your soil encourages overall plant health. Phosphorus ensures sturdy roots -- and along with nitrogen and potassium, forms the "big three" of what plants need. Some plants or nutrient-deficient soils also require specific trace minerals.
- Rodale's Ultimate Encyclopedia of Organic Gardening; Fern Marshall Bradley et al.
- The Garden Primer; Barbara Damrosch
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