Whether you are new to gardening or have been growing plants for years, you may wonder if you need to use fertilizers or plant foods for your plants. Understanding when and why to use fertilizers can help you grow thriving, productive plants.
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What are fertilizers and plant foods?
Fertilizers and plant foods both provide nutrients to plants. The main differences are:
- Fertilizers provide nitrogen, phosphorus, and potassium as well as other nutrients. Plant foods focus more on phosphorus and potassium.
- Fertilizers are usually synthetic chemicals. Plant foods can be natural or synthetic.
- Fertilizers are applied to the soil. Plant foods can be applied to the soil or directly sprayed on plant leaves.
Both fertilizers and plant foods help provide nutrients that plants need to grow and be productive. Determining if you need one, the other, or both depends on several factors.
When do I need fertilizer?
Most plants need fertilizer at some point to provide enough macronutrients and micronutrients for growth. Here are some signs it is time to fertilize:
- New transplants or seedlings are planted – Fertilizing at planting gives young plants a nutrient boost to establish roots and leaves.
- Before the growing season – Fertilizing a few weeks before active growth helps plants prepare for the demands of the growing season.
- During the growing season – Most plants need fertilizer every 4-6 weeks during spring, summer, and fall while actively growing.
- Plants show signs of nutrient deficiencies – Yellowing leaves, stunted growth, or poor flowering and fruiting often indicates a need for fertilizer.
- Soil test recommends fertilizer – Testing your soil every 2-3 years will reveal if essential nutrients are lacking.
Providing fertilizer at the right times encourages vigorous growth and productive plants. Too much can cause damage, so follow package directions.
When do I need plant food?
While fertilizers focus on nitrogen, phosphorus, and potassium, plant foods provide a wide array of essential nutrients. Some signs your plants may need supplemental plant food include:
- Potted plants need feeding – Container plants depend entirely on you for nutrients. Feed them with plant food every 2-4 weeks.
- Early seed development – Sprinkling plant food when plants form buds and baby fruit helps strong development.
- Plants have finished blooming – Feed plants after flowering to replenish nutrients used for blooms.
- Beginning of fall – Plant foods boost nutrient stores before winter so plants emerge strong in spring.
- New leaves look pale – A sign of nutrient deficiency indicating the need for plant food.
Plant food is generally gentle enough to use more frequently than fertilizer if plants are hungry.
Examples of when to use fertilizers vs. plant foods
To see when it is best to use fertilizers compared to plant foods, consider these examples for common garden scenarios:
New vegetable garden
Use fertilizer when preparing soil for new vegetable crops. Mixing in a balanced organic fertilizer provides nutrition for several months. Once seedlings sprout or transplants establish, use a fish or seaweed plant food every 2-3 weeks while actively growing.
Container grown plants
Use slow-release fertilizer pellets when potting up plants. The nutrients release gradually over many months. Supplement with liquid plant foods like compost tea or kelp spray each month.
Established perennial flower beds
Scatter granular fertilizer over the soil in spring and fall. These are times of active root growth. Spray plant food like fish emulsion monthly during the growing season to nourish blooms and foliage growth.
New trees or shrubs
Mix fertilizer into the planting hole and backfill soil when transplanting. Apply plant food to leaves monthly the first year. After establishment, fertilize in early spring and mid-fall each year.
Mature fruit trees
Fertilize lightly in spring as fruit trees break dormancy. Apply plant food every 4-6 weeks during fruit set and development. Stop fertilizing in mid-summer so trees harden off for winter.
General fertilizer and plant food guidelines
Follow these tips for the best results using fertilizers and plant foods:
- Always read and follow label directions on products.
- Use less fertilizer and more frequent plant foods for container plants.
- Time applications appropriately for your climate and the plant’s needs.
- Stop fertilizing 6 weeks before your first fall frost date.
- Consider a soil test every few years to see if amendments are needed.
- If using quick-release fertilizers, apply smaller amounts more often.
- Plant foods are less likely to burn roots or leaves than some fertilizers.
- Rinse foliage after applying plant food to avoid leaf burn.
- Rotate between single-nutrient and complete fertilizer products.
With the right nutrients applied at the right times, your plants will thrive and produce an abundant harvest.
Common fertilizers and plant foods
The table below outlines common options for providing fertilizers and plant foods to your garden:
| Type | Examples | Benefits |
|---|---|---|
| Fertilizers | Urea, triple super phosphate, muriate of potash, blood meal, cottonseed meal, fish emulsion, synthetic chemical mixes | Provide NPK plus micronutrients; designed to feed through roots; last longer in soil than plant foods |
| Plant Foods | Compost tea, alfalfa meal, kelp or seaweed extract, fish emulsion, Epsom salts, molasses | Nourish immediately through leaves or roots; provide wide range of nutrients; gentle enough for frequent feedings |
Look for organic and natural options to improve soil biology and plant health. Consider mixing, matching, and alternating fertilizers and plant foods to give your plants diverse nutrients throughout the growing season.
Conclusion
Fertilizers and plant foods both play important roles in providing the essential nutrients plants need. While some scenarios may call for just one or the other, using them together often offers the most benefits.
Feed transplants, containers, and annuals with gentle plant foods every few weeks. Use more powerful fertilizers less frequently on established plants, trees, shrubs, and perennials. Pay attention to labels for amounts and timing.
With the right balance of fertilizers to build soil nutrients and plant foods to keep plants actively growing, you can have a thriving, productive garden. Test your soil periodically and watch plant signs to determine optimal feeding schedules. With a little time and practice, you can unlock the full growth potential in your garden.