When you picture your dream vegetable garden, I’m betting that there aren’t a bunch of yellow and discolored leaves, stunted greens, and tomato vines with no fruit forming.
Of course not. We all want big, beautiful plants that give us harvest after harvest of shiny green leaves and brightly colored fruits.
If that’s what you want to get out of a garden, there are certain things that you have to put in: sunlight, water, good soil, and, of course, your time and effort to tend it.
There’s one last input to ensure your plants are healthy and have all the nutrients they need to produce for you and fill your harvest basket.
And that’s fertilizer.
Let’s look at when to apply fertilizer to your vegetable garden for best results, plus the different types of fertilizers available, including my favorite organic products.
WHY DO WE FEED OUR VEGETABLE PLANTS?
When a plant first sprouts from a seed, it has all the nutrients it needs to get through its next critical stage of growth. Think about how incredible that is—I mean, imagine if babies didn’t need milk or any other form of nutrition for their first weeks of life!
Once plants are forming leaves and trying to build a strong root system, they need to take in more essential vitamins and minerals in order to keep going. Plants growing in nature can often find what they need from organic material that’s broken down in the soil around them.
The type of plants you might grow in a vegetable garden are often heavy feeders that shoot up quickly and need lots of energy to form flowers and fruits before their relatively short lifecycle comes to an end. They can quickly deplete the nutrients in the soil around them and then need more.
It’s up to you, the gardener, to give them more, and you can do that by fertilizing regularly.
Don’t worry if you’ve ever felt intimidated standing in front of all those fertilizers on the shelf at garden centers. We’ll help you figure out what you really need in a fertilizer to keep your plants happy and how to best apply it.
WHEN TO APPLY FERTILIZER TO YOUR VEGETABLE GARDEN
The best time to apply fertilizer to your vegetable garden is before planting each growing season. This allows the nutrients in the fertilizer to be readily available to the young plants as they grow.
If you missed the planting time, don’t worry. You can still apply fertilizer to your garden during the growing season. Simply scratch in a dry fertilizer into the top couple inches of soil.
Compost, which I’ll talk about more in a bit, can be applied at any point in a plant’s life.
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TYPES OF FERTILIZER
I priortize using organic fertilizers, which are made from natural materials and are slow-release, meaning they release nutrients over a more extended period.
They are a great choice for gardeners who want to avoid synthetic fertilizers. You can add organic fertilizers to your garden soil before planting or apply them during the growing season.
This is a type of dry fertilizer that comes in small, granular pellets or beads. Granular fertilizer can be used to provide nutrients to herbs, leafy greens, root crops, fruiting plants, and flowers.
Most granular fertilizers contain a blend of essential nutrients like nitrogen, phosphorus, and potassium, as well as secondary nutrients like calcium, magnesium, and sulfur.
One of the benefits of using a granular fertilizer is that it provides a slow and steady release of nutrients over time, which allows vegetable plants to absorb what they need at a rate more in line with their growth and development needs. This gradual release of nutrients helps to prevent both over-fertilization and nutrient loss over time.
To apply granular fertilizer to your garden, sprinkle the pellets around the base of the plants and work them into the top few inches of soil. Make sure you follow the manufacturer’s instructions for application rates and timing to avoid over-fertilization.
Liquid fertilizer is a type of plant food that is dissolved in water and applied directly to the soil or sprayed on the leaves of your plants. It is a great option if you want to quickly and easily provide nutrients to your plants. Like granular fertilizer, liquid products are typically a mix of nitrogen, phosphorus, and potassium, plus micronutrients like iron, zinc, and manganese.
One of the benefits of liquid fertilizer is that it is quickly absorbed by the plant’s roots or leaves, providing a fast and efficient source of nutrients. Liquid fertilizer can also be used for foliar feeding, which involves applying the fertilizer directly to the leaves of the plant.
To apply liquid fertilizer to vegetable plants, mix the fertilizer with water according to the manufacturer’s instructions and then pour onto the soil or spray onto the leaves of the plants. Follow instructions regarding when you should next apply (you’ll typically go 2 to 6 weeks between applications depending on the product).
Compost is an excellent natural alternative to synthetic fertilizers and provides many benefits to your garden. Compost consists of decomposed organic waste, such as food scraps and yard trimmings, and once broken down, this organic matter is a nutrient-rich soil amendment that should look (and smell) like soil.
Compost can improve soil structure, increase water retention, and promote overall healthy plant growth.
By using compost regularly as a natural fertilizer alternative, you can provide your plants with a steady supply of the three essential plant nutrients. Compost is also rich in micronutrients like calcium, magnesium, and sulfur, which are necessary for healthy plant growth.
Unlike synthetic fertilizers, which can harm soil health and the ecosystem over time, compost is a sustainable and environmentally friendly way to nourish all of the plants growing in your garden.
You also don’t have to worry about applying too much compost and burning your plants. That just means giving them too much of a certain nutrient. While that doesn’t sound too bad, it can actually kill your plants.
To use compost as a natural fertilizer, spread a 2- to 3-inch thick layer of fresh compost over the existing soil in your raised garden beds, or mix compost into the top couple inches of soil before you plant for your upcoming growing season.
Once plants are growing, you can add a side dressing of compost as often as every week to give plants a little boost. To side-dress just means to add fertilizer around the base of a plant (think right over the rootball).
I like to add a little compost to the planting hole when I’m transplanting seedlings to my garden. You can also use compost instead of mulch around plants to help retain moisture.
Learn more about compost here.
Fertilizer for acid-loving plants
If you’re growing acid-loving plants like blueberries in your garden, consider using a fertilizer specifically designed for these plants, such as MicroLife acidifier. These fertilizers contain higher levels of sulfur, which helps lower the soil pH, creating the acidic conditions these plants need to thrive.
WHAT DO THE 3 NUMBERS ON FERTILIZERS MEAN?
If you’ve picked up any kind of fertilizer from the store, you might notice a trio of numbers written like this: 1-2-3. This is the NPK (nitrogen, phosphorus, and potassium) ratio of the fertilizer. Each number is a percentage by weight of how much of each nutrient is inside, so the higher the number, the more of that nutrient.
Products with different combos of numbers will feed your garden in different ways. This will make more sense once you know a little more about what each of these three essential plant nutrients does.
Nitrogen is essential for healthy leaf growth.
If you notice plant leaves have turned yellow or a paler shade of green, it could mean they’re not getting enough nitrogen.
You’ll want to buy a fertilizer with a higher number for N in the NPK ratio if you’re growing herbs and leafy greens. This will not be the fertilizer that you’d want to use on root crops or fruiting plants like tomatoes. If those plants get too much nitrogen, they’ll focus on forming lots of lush leaves for you and forget about forming the juicy roots or fruits you’re after.
The P in NPK stands for phosphorus, and this nutrient is essential for root development. It also helps plants form flowers, fruit, and seeds. Giving plants phosphorus helps them use other nutrients in the soil more efficiently and absorb energy from the sun.
All of your plants will need at least a little bit of phosphorus, but if you’re trying to grow a root crop or a fruiting plant, you’ll definitely need a fertilizer with a high P ratio.
The K in NPK stands for potassium. (Did you just flash back to the chemistry unit it 7th-grade science too?) Potassium helps water move through a plant. It also helps plants form nice, solid stems just like it helps us with our bone density. All plants need potassium, but it’s especially important for your fruiting and flowering plants.
Calculating Fertilizer Needs
To determine how much fertilizer you need for your vegetable garden, calculate the square feet of your garden bed and follow the manufacturer’s instructions for the specific type of fertilizer you’re using.
For example I use around 1/8th – 1/4th c of Microlife All Purpose per square foot in my raised bed vegetable gardens.
By following instructions with your organic fertilizer of choice, you can avoid over-fertilization, which can damage your plants and harm the environment.
WHAT DOES IT MEAN TO BURN YOUR PLANTS?
I mentioned before that there is such a thing as too much of a good thing when it comes to your plants. Plants need additional nutrients to survive, but too many nutrients given to them all at once can burn them and even kill them.
That’s because too much fertilizer overstimulates the plants. The salt that’s found inside many fertilizers also becomes a problem in too-high quantities. You know how we can cure meat by using salt to slowly pull all the moisture from the cells? Salt does the same thing to the leaves and stems of your plants.
Follow these tips to avoid burning your plants:
- Fertilize the plants growing in your garden according to their need.
- Look for a slow-release fertilizer so that the vitamins and minerals are introduced over time.
- Water the soil around your plants deeply after applying fertilizer to prevent the fertilizer from becoming over-concentrated in certain areas of the soil.
- When in doubt, just use compost. It’s risk-free!
THE BEST FERTILIZERS FOR YOUR VEGGIES
Here are four options that I love to use in my own garden.
MicroLife Super Seaweed
You can use seaweed extract on all of the plants in your vegetable garden, your lawn, and even indoor plants.
Apply seaweed extract to new plants you’re adding to your garden by mixing 1 to 2 ounces per gallon of water. Aim your water over the roots of the plant, not the leaves.
You can also apply seaweed extract as a foliar spray every 2 to 4 weeks. Use 2 ounces per gallon of water in a pump sprayer. Spray plant foilage till you see heavy dripping from the leaves. The best time to spray is early in the morning, especially during hotter months.
MicroLife All-Purpose 6-2-4 fertilizer
Apply all-purpose fertilizer to your garden beds every 3 to 4 months to refresh the nutrients in the soil. You’ll use about 1lb of granules per 25 square feet of space. You can also add this fertilizer anytime you’re adding new plants to the garden.
For smaller gardens, containers, and potted plants, use 1/8th cup per square foot.
MicroLife Ocean Harvest
Use Ocean Harvest on leafy greens and young fruiting plants.
Apply as a foliar spray every 2 to 4 weeks. Mix 2 ounces per gallon of water in a pump sprayer. Spray plant foilage till point of heavy dripping. Again, early morning applications are best.
This fertilizer can be used to stimulate strong root growth as needed. Use 1 to 2 ounces per gallon of water, and aim water at the roots of plants.
MicroLife Maximum Blooms
Use Maximum Blooms on fruiting plants once they’re beginning to flower (you want lots of blooms so they can turn into lots of fruits!) and on any flowering plants.
You can apply this fertilizer by watering around the roots of the plant with a mix of 2 to 4 ounces of fertilizer per gallon of water.
You can also apply this one as a foliar spray every 2 to 4 weeks.
LETTUCE HELP YOU GROW
Fertilizing your garden can feel a little complicated until you get into a rhythm each season. Remember, when in doubt, just add compost!
Lettuce know what kinds of questions you have about fertilizers in the comments below.