Time for mid-season fertilizing!

For many fruits and vegetables, the beginning of summer is the beginning of vigorous growth and production – which takes quite a lot of nutrients to sustain. To give your plants what they need to produce those gorgeous tomatoes, zucchini and kale, they will likely need a boost.

You have a few choices for adding essential nutrients to your garden: compost, granular (dry) fertilizer and liquid fertilizer. Here’s a rundown of each, and how to apply them:

Compost – Not all compost is the same! You might find bagged compost at a garden supply store, maybe you make it in a worm bin in your basement, or perhaps you have a friend with a yard and a big bin full of compost to share. The best compost contains live microbes and smells fresh, like soil after a rainstorm. Unless you conduct a nutrient analysis on homemade compost, or buy compost with a guaranteed analysis, compost is best considered a soil conditioner, and not a fertilizer.

Conditioners help improve the texture as well as moisture- and nutrient-holding capacities of the soil. Why is texture important? Good soil texture helps provide spaces for beneficial soil bacteria and fungi to colonize, as well as pockets of air for roots and organisms such as worms to survive. It also provides an important source of carbon. As the carbon in the compost breaks down, it is released as a gas into the atmosphere, where plants utilize it to carry out photosynthesis.

Granular fertilizer – When shopping for a granular fertilizer, look for an organic all-purpose fertilizer or one formulated for growing fruits and vegetables. Look for the numbers on the package, which signal the percentage of Nitrogen, Phosphorous and Potassium in the mix.

Organic fertilizer label showing the guaranteed minimum analysis for nitrogen, phosphate, potassium, calcium and sulfur.

Organic fertilizer label showing the guaranteed minimum analysis for nitrogen, phosphate, potash, calcium and sulfur.

If you can find a granular fertilizer with addition nutrients such as calcium and sulfur, these are great for fruiting plants such as tomatoes, peppers and zucchini. Fertilizers that contain bacteria and fungi are even better! Think of them as probiotics for your plants – they help break down nutrients so the plant’s roots can take them up more efficiently.

Label on organic fertilizer showing additional bacteria and fungi in the product.

Label on organic fertilizer showing additional bacteria and fungi in the product.

Granular fertilizers are for long-term plant health. Apply this as a side dressing (shown below) to feed your plants for the next several weeks. Do not use more than the package indicates – more is not better!

Swiss chard with a side-dressing of granular fertilizer. Be sure to put this a few inches away from the plant's stem. It's also a good idea to scratch it into the soil surface, then water well so the nutrients will absorb into the soil.

Swiss chard with a side-dressing of granular fertilizer. Be sure to put this a few inches away from the plant’s stem. It’s also a good idea to scratch it into the soil surface, then water well so the nutrients will absorb into the soil.

 

 

 

 

 

 

 

 

 

 

Liquid fertilizer derived from seaweed and fish.

Liquid fertilizer derived from seaweed and fish.

Liquid fertilizer – This is what you need to use if your plants already have yellowing lower leaves, or if they have a purple tinge on the underside. Liquid fertilizers will deliver the nutrients to your plants a lot more quickly than the dry ones. Fish or seaweed emulsions are a good choice. Follow the directions on the package carefully – too much fertilizer can burn your plants. In most cases, you’ll add a few tablespoons of fish emulsion to a gallon of water, which is then mixed and applied to the soil near the plant.

To sum it up:

Compost – add to improve soil texture, moisture/nutrient-holding capacity, organic matter (carbon)
Granular fertilizer – for long-term plant nutrition, the broader range of nutrients the better, added bacteria/fungi are a big bonus!
Liquid fertilizer – quick fix for nutrient-related plant problems, not ideal as a long-term feeding solution