Side dressing with fertiliser is a horticultural technique used to supply plants with additional nutrients during the critical phases of their growth cycle. This method involves applying fertiliser to growing plants, rather than to unplanted soil at planting time.
Fertiliser is typically incorporated (dug) into the soil during initial bed preparation, before planting. After the plants are established and growing, they might require more nutrients. However, deep digging around growing plants to incorporate additional fertiliser could damage their roots.
Side dressing provides a solution by allowing gardeners to apply extra fertiliser around the plants without disturbing the roots, ensuring the nutrients reach the soil where they can be readily absorbed by the plants.
Side dressing is essential for maintaining nutrient availability and supporting plant growth, particularly in fast-growing crops which are heavy feeders that deplete soil nutrients quickly.
The Importance of Side Dressing Growing Plants
Plants require a steady supply of nutrients throughout their life to thrive, produce high yields, and ward off pests and diseases. Initial applications of fertiliser at planting time can be insufficient for the entire growth period, especially for long-growing plants. Side dressing helps replenish these essential nutrients, ensuring that plants receive them at their most critical growth stages.
When to Side Dress the Garden
The timing of side dressing varies depending on the type of plant and its specific growth stages. Generally, side dressing is most beneficial when plants enter a rapid growth phase or start producing fruit. For example:
- Vegetables: Side dress leafy vegetables like lettuce and spinach about four weeks after planting. For fruiting vegetables such as tomatoes and peppers, apply a side dressing when the first fruits begin to form.
- Flowers: For flowering plants, side dressing can be done as they begin to set buds, providing them with the necessary nutrients to bloom abundantly.
- Lawns: For grass, side dressing is usually applied in early spring or late summer to help rejuvenate the turf after winter dormancy or summer stress.
Types of Fertilisers Used for Side Dressing
Fertilisers used for side dressing are typically high in nitrogen, which is crucial for leafy growth. However, the specific nutrient needs depend on the plant’s current stage and overall health. Common materials include:
- Granular Fertilisers: Slow-release granules are popular for their ease of use and prolonged nutrient release.
- Liquid Fertilisers: Fast-acting and ideal for quick absorption, they are particularly useful during critical growth phases.
Organic fertiliser options include composted manure, worm farm castings, fish emulsion, blood & bone, and balanced organic fertiliser pellets.
Seaweed extract is not a fertiliser, but more of a plant tonic that stimulates root growth and helps young plants establish faster. Depending on how the seaweed extract is produced, it may also contain the nutrient potassium (potash), which supports flowering and fruiting, making it excellent for combining with fertilisers low in potassium such as manures or blood & bone.
Additionally, organic fertilisers rich in organic matter, such as manures and worm castings improve soil structure while providing nutrients.
For more information of fertilisers, see article – The Organic Gardener’s Guide To Fertilisers And How To Use Them
How To Apply a Side Dressing of Fertiliser to The Garden
The application of side dressing should be done carefully to avoid damaging the plants. Here’s how to properly side dress with fertiliser:
- Maintain Distance from Plants: Fertiliser should be applied about 15-20 cm (6-8 in) away from the plant stems. This prevents root burn and ensures that the nutrients are absorbed by the roots as they grow and spread outward to reach the fertiliser.
- Application Technique: For granular fertiliser, gently scratch it into the soil surface, and then water thoroughly to help the nutrients seep into the soil. For liquid fertilisers, dilute as recommended and apply to the soil at the base of the plants. Solid fertilisers are not effective when left exposed on the soil surface, as they may lose nitrogen, a vital nutrient that can volatilize into the atmosphere.
- Use the Right Amount: The amount of fertiliser required varies based on the type of plant and the fertility of the soil. Applying too much fertiliser can be as detrimental to plants as not applying enough. Therefore, it is crucial to consult the fertiliser’s label for precise application guidelines. For application rates of unlabeled manures, see article – Manure Application Rate, How Much Should We Use In The Garden?
Precautions and Tips When Side Dressing with Fertiliser
- Avoid Over-Fertilisation: Excessive use of fertiliser can harm plants, leading to root burn, and is wasteful with detrimental effects, causing nutrient runoff and environmental pollution
- Monitor Plant Response to Fertiliser Application: After applying a side dressing of fertiliser, observe the plants for signs of improvement or any adverse reactions. Patience is key, as it takes time for plants to absorb nutrients and exhibit new growth. Solid, slow-release fertilisers require time to become effective, and natural, organic fertilisers depend on soil microorganisms to break them down and release their nutrients for plant uptake.
- The Question of Soil Testing: Before side dressing, a soil test can be beneficial to determine the existing nutrient levels and pH, enabling more precise fertiliser applications—particularly in farming operations. Soil tests are expensive, and they’re not essential for home gardens to track nutrient levels. In contrast, they are only crucial in large-scale agricultural settings where the cost of fertiliser is significant, and judicious application can result in substantial savings. Therefore, it’s often inappropriate or ill-advised to apply agricultural recommendations to home gardens.!
In summary, side dressing is a targeted, efficient way to manage soil fertility and promote healthy plant growth. By understanding the nutrient requirements of plants and applying fertilisers accordingly, gardeners can significantly enhance their garden’s productivity and beauty. Proper timing, correct fertiliser selection, and careful application are key to the success of side dressing, making it a vital skill for any gardener.