We humans have been growing food for a hot minute. Roughly 10,000 – 12,000 years, depending on who you ask, but who’s counting? We’ve gotten pretty good at it, too.
Everything we grow in our vegetable gardens today started as some scrappy wild plant. We took it and bred it to expand on a trait we enjoyed – flavor, texture, size, hardiness, etc.
Along the way, we figured out that adding certain organic materials to the soil improved how well our plants grew. And in our very human way of desiring everything to be bigger, stronger, and faster, fertilizer became an important tool in our garden shed.
One we reach for with increasing regularity as soil fertility dwindles.
Of course, we’re learning about the harmful effects that some of these fertilizers can have on our waterways if we use them too often. More and more, gardeners are focusing on rehabilitating their soil through practices like no-dig and regenerative gardening.
Fertilizer has its place, and, yes, it’s an important tool for gardeners. Far too often, though, we fertilize indiscriminately, using it as a panacea across the whole garden. There are quite a few vegetables in your garden that don’t need to be fertilized. In fact, for some of them, it can do more harm than good.
Many of these vegetables have adapted to grow in soils that don’t have a lot of nutrients or “lean” soils. Suddenly, dousing them in fish fertilizer or Miracle Gro can make them less flavorful, more susceptible to pests and diseases or make the wrong part of the plant grow (i/e., the part you don’t eat).
Let’s take a look at these scrappy garden occupants.
Vegetables That Require Low or No Fertilizer
1. Root Vegetables
Basically, anything that grows bulbous underground prefers lean soil. So, all of your root crops like carrots, beets, parsnips, radishes, and turnips will do best in soils that are not overly rich in nitrogen.
This is one situation where fertilizing can leave you with the opposite desired effect. Excess nitrogen will give you lots of lush foliage above ground with little to no root development underground. And while I’m a huge fan of beetroot leaves, I still want to eat the beets, too. Give these guys plenty of well-draining, loose soils and don’t worry about the fertilizer.
2. Beans and Peas
Legumes are well known for their ability to fix atmospheric nitrogen in the ground. They do this with the help of Rhizobium bacteria in their root nodules. Because of this little symbiotic friendship, legumes rarely need additional fertilizer.
However, if you plan to follow the old advice of using beans and peas to fertilize the soil for future crops (crop rotation, anyone?), you might want to read what Dawn has to say about using beans to “fertilize” your other crops here.
3. Alliums
Veggies in the allium family – onions, garlic, and my favorite, shallots should definitely not be fertilized. These guys are super sensitive to high nitrogen in the soil, which, again, like our root vegetables, leads to all leaves and no bulbs.
Not really what we’re going for with alliums.
4. Lettuce & Spinach
Okay, this one might seem counterintuitive, as we’re trying to grow lush foliage with both of these crops. But hear me out – go easy on the fertilizer if you want flavorful lettuce and spinach.
Too much fertilizer can cause the plant to grow too quickly and bolt. This means you end up with a bitter-tasting salad instead of the crisp, clean taste you were hoping for. The best thing you can do for lettuce and spinach is to ensure they’re watered consistently.
They don’t necessarily need lean soil, but they also don’t need you to lend a helping hand by adding fertilizer.
5. Arugula, Mustard & Other Spicy Greens
When it comes to greens grown for their spicy bite, fertilizer can backfire. Much like lettuce and spinach, it causes the plants to grow too quickly, but you also lose the flavor. These greens generally do best in leaner soil. If you want more flavorful arugula, mustard, and other spicy greens, plant them in lean soil.
6. Potatoes
When it comes to potatoes, phosphorus and potassium are much more important than nitrogen in developing beautiful golden spuds. In fact, too much nitrogen can lead to a higher risk of the potatoes rotting. That’s because it makes the potato skins much thinner, so any nicks or scratches will introduce bacteria, and the potato will go bad. If you’re growing potatoes that you plan on storing, thick skin is important.
7. Herbs
Okay, okay, these aren’t vegetables, but if you cook and have a garden, I’ll bet you grow these guys, too. Which means you’re really going to want to stop fertilizing your herbs.
Believe it or not, you’re actually making them less flavorful when you do.
Their flavor comes from essential oils and is totally dependent on the potency of those oils. Rich soil, filled with nutrients, increases quick growth, which means there is less of the essential oil in the plant. (It’s prioritizing growth over making the oils.) So, while your basil plant might be bigger and more lush if you fertilize it, the actual basil will be far less flavorful.
Not to mention, when they grow quickly, they aren’t as strong, and the plants can flop over on their own or in a summer storm.
A Few Important Things to Keep In Mind
Soil Preparation
Get your soil tested. It really is the best thing you can do for your garden. You’ll receive so much insight into what’s going on below your feet. Not only can you find out if you even need fertilizer at all, but you’ll know your soil’s pH and whether or not there are any deficiencies.
Remember, these plants need and use the same nutrients that your heavy feeders do; they just require much less. Often, what’s already available in the soil is all they need.
Crop Rotation
A great way to put crop rotation to good use when it comes to low-fertilizer vegetables is to plant them in the same spot you had a heavy feeder the year before, so tomatoes, peppers, and squash. These nutrient hogs can leave the soil lean enough to accommodate your root crops, legumes, etc.
Mulch Can Help
Adding some type of organic material as mulch each year not only helps you out by suppressing weeds and locking in moisture, but it also slowly improves your soil as it breaks down. This means you need less fertilizer in the future.
Use Compost for Low & Slow Nutrients
By adding well-decomposed compost into your garden, you’re adding small doses of nutrients that are released slowly into the soil over time, so your plants are supported with the need for lots of fertilizer.
In the end, the best thing you can do for your vegetable garden is to have your soil tested. While fertilizer is a great tool in the gardener’s tool shed, our tendency to over-fertilize could lead to less flavorful vegetables and smaller yields.
Read Next:
Tomato plants are one veg garden plant that do need a little extra nutrition through the season for big harvests. Here’s our guide to fertilizing tomato plants right through the season.
Get the famous Rural Sprout newsletter delivered to your inbox.
Join the 50,000+ gardeners who get timely gardening tutorials, tips and tasks delivered direct to their inbox.