10 Biggest Mistakes When Planting a Vegetable Garden

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With over a decade of experience as a gardener, I have made a few mistakes. Okay, I’ve made countless mistakes over the years, but it has only made me a better grower!

So, with another gardening season ahead, I wanted to share my top 10 biggest mistakes you can make when planting a vegetable garden. Whether you are brand new to growing your own food, or have a few seasons under your belt, hopefully you can learn something new.

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Mistake #1: Overcrowding Plants

One of the most common problems I see newer gardeners face is crowding. When seedlings are young, they are small, so it seems logical to plant them close to one another.

Flash forward a month and your plants are fighting each other for resources. Overcrowding is worse with certain plants, such as tomatoes and other disease-prone crops.

Make sure to check the spacing recommendations for each of the plants you will be growing and stick to it. While your garden may look sparse in the first few weeks, it will fill in quicker than you think!

Mistake #2: Planting Seeds Too Early

It is too easy to plant seeds. Early on in my growing journey, I would plant pepper seeds in February (in zone 6a). That is way too early for my region, and today I plant in mid-late March.

Every crop is different, so it helps to research and ask around in your area. Look for local master gardener’s programs where you can often find planting recommendations for common vegetables.

For seed starting, we usually recommend using the average last frost date as a reference point. In other words, plant your seeds a certain number of days before/after your last frost date.

Mistake #3: Not Using Mulch

Mulch adds serious benefits to your garden. Whether you use organic mulches (which we recommend), or black plastic, it is always beneficial.

Benefits of mulch:

• Suppresses weeds
• Retains moisture in soil for longer
• Insulates roots from cold/hot weather
• Protects soil from erosion
• Reduces soil splashing
• Adds nutrients to the soil over time

Mulch is a no brainer. Simply add a 2-3″ layer around your plants after they are at least 4-5″ tall. If you need to amend the soil or add more plants, you can just move the mulch aside temporarily.

My favorite mulch to use is leaf mulch. In the fall, we collect up all the fallen leaves in the yard, mow over them with the lawn mower, and use the shredded leaves as a mulch. It’s free, does not contain any herbicides/pesticides, and breaks down slowly to improve our garden soil.

Wood chips are the most common type of mulch available at big box stores. You can get bagged or bulk mulch, depending on how large your garden is.

Mistake #4: Shading Out Sun-Loving Plants

Most garden vegetables need full sun in order to grow best. This means that we have to arrange the plants thoughtfully to avoid shading out smaller plants with bigger ones.

The general rule is to plant your tallest plants on the North side of your garden, and the shortest plants on the South side. This allows the sun to hit all your plants, all day long. (If you happen to be in the Southern hemisphere, the rule is reversed).

If you don’t have a full-sun location, find a spot with maximum sun exposure. Avoid any areas that are against the North-side of a building, tree, or other tall structure.

Mistake #5: Moving Plants Outside Too Early

Story time: A warm day comes along in early spring, luring you outside to plant some veggies. 3 days after you planted your frost-sensitive plants, a freeze comes overnight, damaging the leaves and stunting their growth. 🤦🏻‍♂️

If this touches a soft spot, you’re not alone. I have been guilty of moving peppers and tomatoes out long before I should have, with devastating consequences.

Now, I always recommend to wait for overnight temperatures to be consistently in the mid 50s or low 60s before transplanting warm weather crops. This is a fail-proof method that doesn’t rely on “average” last frost dates (which can be very different in any given year).

Mistake #6: Not Hardening Off

Similar to moving out too soon is moving your plants outside too abruptly. If you start plants from seed indoors (under grow lights or even in a window), they need to be hardened off.

This is the process of gradually transitioning plants from inside to outside. This slow introduction to direct sun, wind, and precipitation will help avoid stressing your plants. Sun scald is a common result of not hardening off, commonly presenting as white, crispy dead leaves.

Bring your plants outside on a cloudy day with warm temperatures to start. Let them take in the filtered light for an hour or two. Then, bring them back inside.

The next day, add 30-60 minutes to the outside time. Keep increasing the time for 1-2 weeks until the plants can handle sunshine all day.

Mistake #7: Planting Cold Weather Crops In Summer

If you like lettuce, spinach, bok choy, broccoli, or cauliflower, then you need to get started early. These plants all like cooler temperatures.

In hot weather, your cool weather crops may bolt (flower prematurely), or simply not produce the desired result. Once a lettuce plants has bolted, the leafy greens will be bitter and unappetizing.

So, make sure to plant early enough for your cool weather crops, and don’t bother planting in the dead of summer. However, you can plant seeds in later summer to get a fall crop when the temperatures drop again.

Mistake #8: Not Supporting Large Plants

Most gardeners know that tomatoes should be supported (tomato cages are sold at every garden center). But there are countless other crops that also need some help staying upright.

Pole beans, peas, cucumbers, and even melons all like to climb as they grow. Eggplants and peppers can also become top-heavy later in the season, benefiting from cages.

It is best to install your support structures early (usually at the time of transplanting). This will prevent damage to your plant’s roots or branches later in the season.

Mistake #9: Not Cleaning Up

After a gardening season ends, it is easy to be lazy and let the dead plants sit all winter long. Don’t make this mistake! Dead plants and fallen fruits are used by many pests to overwinter in your garden.

If you don’t clean them up, you are helping any pests to simply re-emerge in spring to feast on next year’s garden. Instead, clean up the garden, compost whatever you can, and burn anything the can’t be composted.

It is also a great idea to cover your soil for the winter. This could simply be a layer of mulch, or a tarp to help prevent leeching nutrients and erosion.

Mistake #10: Growing More Than You Can Use

Finally, it is a classic mistake to plant more than you can use. Seed catalogues are incredibly tempting with their beautiful colorful pictures of every fruit and veggie under the sun.

However, overwhelm is a real thing. Don’t bite off more than you can chew, and especially don’t plant foods that you won’t eat.

A great example: I once grew over 20 superhot pepper varieties in a single season. While the plants were amazing and fun to grow, I had no plans on how to use them all up. I ended up with a lot of spicy powder that is still kicking around to this day (at least is makes a good animal deterrent…).

So, in short, grow what you love! If you love to eat jalapeños, grow lots of those. If you can’t get enough salad greens, make them a priority. Planting too much can cause you to cut corners and end up with a poor result in the end.

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I hope this article helps you to avoid some of the common gardening mistakes. Like I said, I’ve made most of the mistakes on this list! It is okay to mess up, just do your best to learn from it and move forward a better gardener.