Why are my carrots short and fat? Well, carrots can be a tricky vegetable to grow, and harvesting a bed of short, stubby carrots is one of those unwelcome surprises that are all too common when you start to grow your own vegetables.
Carrots grow short and fat for several reasons:
- Wrong carrot variety
- Shallow soil
- Heavy soil
- Wrong soil pH
- High Temperatures
- Too much or too little water
- Pests and diseases
The reason your carrots grew short and fat could be down to one easy-to-remedy problem or multiple factors could be involved.
A big part of growing vegetables is learning from our mistakes, so dive into this post with me and find out how to fix your growing conditions and avoid another short, fat carrot harvest.
Why Do Carrots Grow Short And Fat?
Before we get into the specific reasons carrots grow short and fat, it’s important to realize that you’ll get variations with every carrot harvest. Some of your carrots will produce fantastic roots and others in your crop will be disappointing.
Even commercial carrot growers experience losses from their harvests because some of their carrots (around 5%) aren’t pretty enough for grocery stores or of a usable size for food processing plants. Those short and misshapen carrots get plowed back into the ground.
The long, straight, blemish free carrots you get from the grocery store are the best of the harvest. And just like carrot farmers, home growers usually find a few disappointing carrots when we pull up our crop.
That being said, as a home grower, you can pay more attention to your carrot bed than a farmer with dozens of acres to take care of.
To Avoid Growing Short, Fat Carrots You Need To Get The Following Things Right
Carrot variety: Choose a medium-to-long carrot variety. Grocery store carrots are usually Imperator types, while the most popular types for home gardens are Nantes or Chantenay types which are shorter (see below).
Soil type: Soil should be loose, crumbly, and free-draining
Soil depth: Soil should be the depth of the mature carrot plus 2” to 3” (5 cm to 8 cm).
Soil moisture: Carrots need moist soil, don’t let it dry out.
Soil pH: Carrots tolerate a soil pH of 5.5 to 7.0, but carrots thrive in soil with a pH of 6.0 to 6.8.
Temperature: Carrots grow best in a cool climate, they aren’t a summer crop in hot regions. You’ll get better harvests in the spring and fall.
Spacing: Overcrowding carrots stunts their growth, so give each plant the room it needs.
Pests and diseases: Pests and diseases affect carrot growth and both can lead to stunted carrots.
Let’s look at each one in more detail.
To Grow Longer Carrots Choose The Right Type Of Carrot Seed
Carrot variety is the first thing to check. Did you grow a long variety that produced short, fat carrots because of your growing conditions, or did you inadvertently sow seed from a short, stubby carrot variety?
If you look through a seed catalog, you’ll soon discover the many kinds (and colors) of carrots you can grow.
Some carrot varieties grow long, straight carrots; others produce short, fat carrots, or round carrots.
Carrots fall into one of 5 main categories relating to shape and size. These categories are called types, and each type has many varieties.
The 5 Main Carrot Types
Imperator: Long, slender carrots with a tapered end grow up to 12” (30 cm) long.
Danvers: Half-long carrots have a blunted end and grow 6” to 8” (15 cm to 20 cm) long.
Nantes: Long, cylindrical carrots with a rounded end grow up to 7” (18 cm) long.
Chantenay: Shorter carrots with a fat uniform shape grow up to 5.5” (14 cm) long.
Ball/Mini: Short, round ball carrots grow 2” (5 cm) long. Mini carrots grow up to 3” (8 cm) long.
Shorter, fatter carrot varieties are ideal for home gardeners with shallow soils, or with heavier clay soils.
Is Shallow Soil The reason Your Carrots Grew Short And Fat?
Now, let’s figure out if your growing bed has deep enough soil to grow long carrots.
Carrots thrive in deep, loose soil.
According to The British Carrot Growers Association, the ideal loose soil depth for carrots is 50 to 75 mm (2” to 3”) deeper than the mature carrot length.
If, for example, you want to grow Scarlet Nantes carrots, which grow up to 7” long (18 cm), then you’ll need a loose soil depth of 10” or 25 cm.
But if you decide to grow a ball or mini type carrot, you only need a loose soil depth of 6” (15 cm).
Is Your Soil Too Heavy And Compacted To Grow Long Carrots?
Long carrot varieties need loose soil with good drainage.
What counts as loose soil?
Loose soil is soil which is friable or crumbly. If you scoop up a handful of soil and try to break it apart with your fingers, it should come apart easily.
Because carrots are a root vegetable, they need soil which is easy to grow down into.
Heavier soils, those soils with a high percentage of clay, are hard for growing carrots to push through.
If your carrot growing bed has clay soil, your carrots will be stunted and you’ll get short, fat carrots at harvest time unless you add organic matter and/or sand to amend your soil before you sow your carrot seed.
Stones in your soil are another reason you could end up growing short, fat carrots. Carrots can twist or split and fork around small stones, but larger stones will stop them in their tracks.
Friable soil also drains well. Carrots need a moist soil but they don’t like waterlogged soil.
When soil is waterlogged, carrot roots can’t get enough oxygen and they don’t grow well. In severely waterlogged soil, your carrots plants will die.
Soils with a heavy clay content are slower to drain and more likely to become waterlogged in wet climates.
If you’re stuck with heavy soil in your garden, amend your soil with aged compost and sand, or create raised beds and fill them with more suitable soil. Just look for a topsoil supplier in your area that delivers bulk or bagged soil.
Another option you could try is growing carrots in containers or 5 gallon buckets, but that’s not really practical if you want to grow hundreds of carrots each year.
Soil in containers also dries out rapidly, and containers can get too hot for carrots. But if you plan to grow spring or fall carrots and avoid the heat of summer, then growing carrots in containers is a viable option.
How To Tell If Your Soil Is Suitable For Growing Long Carrots
Check the soil in your carrot bed: is it loose?
Take a hand trowel and see how easily you can dig down into your carrot growing bed.
If your soil is loose, you won’t meet any resistance and you won’t need to push down very hard on the trowel.
Check multiple spots in your growing bed to make sure the soil is loose at the depth your carrot variety needs.
Loose soil is easy to work with your hands. If you can scoop soil away with your fingers and make a nice deep hole, you’ve got loose soil.
Test Your Soil Texture
Next, test your soil texture to find out if you’ve got clay soil, sandy soil, loamy soil or silty soil. Most soils are a mixture, but one soil type will dominate.
It’s easy to test your soil texture and you don’t need any special equipment. All you need is your hands and some damp soil for a squeeze test, or a glass jar and water for a settle test.
Squeeze Test: Basic Soil Test To Find Your Main Soil Type
Take a small scoop of damp soil and squeeze it in your hand.
Clay soil is sticky and will easily hold together and form a clump in your hand.
Silty soil is less sticky than clay. It will hold its shape when squeezed together, but not as firmly as clay. If you push the clump around with your fingers, it will change shape easily.
Sandy soil isn’t sticky at all and when you open your hand, the soil will fall apart.
Loamy soil has a nice blend of soil particles, some sand, some clay, and some silt. It will form a clump when you squeeze it, but if you poke it with your finger, it will easily come apart again.
A Settle Test Gives You A More Thorough Soil Analysis
A large glass jam jar or mayonnaise jar is perfect for this test.
Take some soil from your growing bed and remove stones, roots, and other debris.
Fill the jar 1/3 with soil. Add water and one drop of dish soap to the jar, leaving a couple of inches of headspace at the top.
The detergent acts as a surfactant to help the soil particles separate.
Screw the lid on the jar, and give the jar a thorough shake to mix the soil and water into a slurry. Place the jar on a flat surface and leave it to settle for 48 hours.
If you want to keep a check on the soil test progress, follow these timings.
After 1 minute – The sandy parties will settle first because they’re the largest and heaviest particles. Take a marker pen and draw a line on the jar to mark the top of the sand layer.
After 2 hours – the silt particles will settle on top of the sandy layer. Draw another line to mark this layer.
After 48 hours – the tiny clay particles have settled out. Draw another line to mark the clay layer.
Which layer is the biggest? If it’s the sandy layer, you’ve got predominately sandy soil. If it’s the clay layer, you’ve got mostly clay soil, and if it’s the silt layer, then silt is your major soil type.
If you’ve got even layers, or close to even layers, you’ve got loamy soil.
Now you know what type of soil you’ve got, you can add soil amendments to improve your soil and grow better carrots.
Is Your Soil Too Wet For Carrots? How To Run A Soil Drainage Test To Find Out
Carrots need moist but well drained soil. If you try to grow carrots in soil that holds too much water, you’ll get short carrots. If the soil is waterlogged for long periods, the carrot roots will die and the carrot will rot.
Dig out a hole in your carrot bed or in the area you plan to use for your next carrot bed. Aim for a hole 12” wide and 12” deep.
You need to fill this hole with water twice.
Fill the hole with water and wait for the water to drain. If you do this in the evening, you can leave it to drain overnight. The purpose of this first fill is to saturate the surrounding soil with water so you get a realistic soil drainage measurement on the second fill.
Measure the depth of the hole with a tape measure.
Fill the hole with water again and time how long the water takes to drain – Leave the hole for 1 hour then measure the drainage with a tape measure.
Drainage is ideal for carrots and other vegetables if the water drains between 1” and 3” per hour.
If the water level decreases by less than 1” per hour, your soil has poor drainage and you’ve got a heavy clay soil.
If the water level drops by more than 4” in one hour, your soil drains too fast, indicating sandy soil.
Loamy soil is the ideal soil for vegetable gardens and carrot beds. With regular watering, loamy soil stays moist without getting water logged. Loamy soils also provide the best conditions for the soil organisms which produce nutrients for your vegetables.
Because loamy soil retains moisture, it will hold on to any fertilizer you apply and make it available to your plant roots for a longer period.
Clay soil gets waterlogged easily. You’ll need to amend the soil and dig in organic matter and sand to improve drainage and reduce soil compaction.
Dense, clay soil takes longer to warm up in the spring. Cover growing beds with black plastic to help warm the soil, then remove the plastic before sowing seed.
It’s not all bad news if you’ve got clay soil. Clay soils hold nutrients well, so if you can improve the drainage in your growing beds with soil amendments, and work the soil to a fine, loose texture, you’ll get a decent growing medium.
Silty soil is fine for carrots. It holds moisture and nutrients well without getting waterlogged in a wet climate. Even so, a little aged compost will give your soil and your harvest a boost.
Sandy soil is easy to work, but it dries out fast and doesn’t hold nutrients as well as heavier soils. The loose soil is ideal for carrots because they can penetrate the soil easily as they grow, but you’ll need to water more frequently to stop the carrot beds from drying out. Mulching your carrot beds with straw or compost will help slow down surface water loss.
If you’ve got sandy soil and you live in a wet climate, you’ll need to feed your carrots more regularly because rain washes nutrients out of sandy soil.
Sandy soil will benefit from the addition of aged compost to slow down water loss and hold nutrients.
Next, let’s investigate your soil’s pH level.
What Soil PH Do Carrots Need For Strong Growth?
Soil pH can make or break your carrot harvest.
Carrots tolerate soil with a pH that’s between 5.5 and 7.0.
Carrots thrive in soil with a pH of 6.0 to 6.8.Source: gardening.cornell.edu
If you don’t know what pH is and why it’s important to know your soil pH, come on a little science lesson with me.
PH is a measure of how acidic or alkaline a substance is. The pH scale runs from 1.0 to 14.0.
- 1.0 to 6.0 is low pH.
- 7.0 is neutral (7.0 is the pH of water).
- 8.0 to 14.0 is high pH.
Substances with a low pH are acidic, and the lower the pH score, the more acidic the substance. A tomato has a pH of 4.0. Lemon juice scores pH 2.0. Stomach acid comes in at pH 1.0. And battery acid is pH zero.
Substances with high pH are alkaline. Your blood has a pH of 8.0 Baking soda is pH 9.0. Soap is pH 12.0, and drain cleaner is pH 14.0.
So what does this have to do with soil?
Soil pH determines how well soil releases nutrients to plants. A soil pH of 6.5 makes the widest range of nutrients available to plants.
Low soil pH (acidic soils) inhibits the release of phosphorus, and acidic soil isn’t a good environment for the beneficial soil bacteria, which are essential for a healthy soil and healthy plants. Soil with a pH of 5.0 or below has a high acid content.
In high pH soil (alkaline soil) plants have less access to iron, copper, manganese, and zinc. Soil with a pH of of 7.5 and above has a high alkaline content.
Different vegetables have different nutrient needs, and some thrive in a more acidic soil while others will tolerate a more alkaline soil. For example, potatoes love to grow in a slightly acidic soil with a pH of 4.5 – 6.0. While leeks and asparagus prefer soil with a pH between 6.0 to 8.0.
So, how do you know if you’ve got acidic, neutral, or alkaline soil?
You test it.
Soil testing kits are one way to test your soil pH, and you can pick up a soil testing kit from Amazon or any garden supply store.
Testing kits come in 2 types. Chemical and digital.
With chemical additive kits, you need to add powdered or liquid chemicals to a sample of soil mixed with water. These kits also contain chemicals that let you measure the nitrogen (N), phosphorous (P) and potassium (K) levels in your soil.
The second type of kit uses a digital meter and a probe to measure soil pH. Digital pH meters are reusable and they give you an instant reading from any part of your garden without needing to take soil samples and mix chemicals.
However, soil test kits are a bit pricey for what they are, and you can test your soil just as well with any litmus testing strips, like those you use to test the pH of urine or saliva.
Pick those up cheaply at any pharmacy. Just make sure the strips you buy have a range that covers at least pH 4.5 to 10.
To use pH strips, mix equal amounts of soil and distilled water to make a muddy slurry. Touch a pH strip to the mud mixture and wait for the color on the strip to develop.
Then compare the color at the end of the strip to the color chart to get your pH reading.
If you’re on a tight budget, you can get a rough idea of your soil’s pH with a simple DIY test.
How To Run A DIY Soil PH Test
For the DIY soil pH test, you’ll need 2 containers (empty, washed yogurt pots are ideal) vinegar, baking soda and water (preferably distilled water).
- Add 1 teaspoon of soil to each container.
- Add half a cup (120 ml) of vinegar to the first container.
If it fizzes, your soil is alkaline. The pH will be between 7.0 and 8.0. Your soil is too alkaline to grow good carrots.
If the soil and vinegar didn’t react, test the second soil sample.
- Add half a cup (120 ml) of distilled water to create a muddy mixture.
- Add half a cup (100 g) of baking soda to the container.
If the mixture fizzes, the soil is acidic with a pH between 5.0 and 6.0. This soil could be too acidic for carrots to thrive.
If the soil didn’t react at all, you’ve got neutral soil with a pH of 7.0. Carrots will grow fine in your soil.
Carrots can tolerate pH 5.5 to 7.5.
The ideal pH range for carrots is 6.0 to 6.8
If you discover that your soil is too acidic, or too alkaline, the pH level could be the reason your carrots struggled to produce long roots.
Crop researchers at Oregon State University found carrots grown in soil with a pH of 5.6 produced a 60% bigger yield than carrots grown in soil with pH 5.0. That slight difference in pH had a big effect at harvest time.
To lower the pH of an alkaline soil, add sulfur, ammonium sulfate, or an acidic fertilizer.
To raise the pH of acidic soil, add mineral lime or wood ash to your soil, and avoid using nitrogen rich fertilizer or compost.
Next, let’s find out how temperature affects carrot growth.
Carrots Are A Cool Season Crop: High Temperatures Stunt Growth
Carrot seed needs warm soil temperatures to germinate but then, for best growth, they prefer cooler temperatures.
The ideal soil temperature range for carrot seed germination is 50°F (10°C) to 85°F (29°C), with 80°F (26°C) being the optimum temperature.
At 80°F (26°C) carrots seed germinate in 8 to 14 days. If you sow seed at lower soil temperatures, it will still germinate, even as low as 40°F (5°C) but will take longer and the germination rate (the percentage of seed that germinates) will be lower.
At 95°F and above (35°C), germination won’t take place.
Suboptimal germination temperature also has a long-term effect on plant growth because it produces plants with reduced vigor.
In plants, vigor is strength. And carrot seedlings with good early vigor will grow faster instead of struggling to establish themselves. Better vigor also leads to stronger root development, and that’s crucial for a good carrot crop.
What’s The Ideal Temperature For Carrots Once They’ve Germinated? How Do Temperatures Outside That Ideal Affect Carrot Growth?
Carrots will grow best and be sweetest when temperatures are between 40°F to 80°F (5°C to 26°C).
As you can see from that temperature range, hot summers aren’t good for growing carrots.
A study carried out at the Department of Soil, Crop and Climate Sciences, at the University of the Free State in South Africa, showed how temperature affects carrot growth and crop yield.
Researchers grew carrots in pots in temperature controlled chambers at 50°F (10°C), 64°F (18°C), 79°F (26°C), and 89°F (32°C). The pots were 35 cm (13.5”) deep, giving plenty of room for carrots to grow.
The study found that carrots grew best and produced the biggest carrots at 50°F (10°C) growing longer roots with more root mass.
Overall, carrot growth at 64°F (18°C) was significantly lower, and the roots were shorter.
If you grew carrots when your temperatures were over 50°F (10°C), the higher temperature could have been the reason or part of the reason your carrots were short.
Of course, it’s virtually impossible for home growers or farmers to germinate and grow carrots at the optimum temperatures discovered in controlled test environments.
Once soil has reached the optimum temperature for germination, the temperature is too warm for optimum growth.
So what can a home grower do?
Warm Your Growing Bed Prior To Sowing Carrot Seed
Lay black plastic over your carrot bed for a couple of weeks before you sow seed in early spring after your last frost date.
Black plastic will increase soil temperature by 5°F (2.5°C).
Early spring soil temperatures are at the lower end of the scale for carrot seed germination, so warming up the soil by a few degrees will give you a higher germination rate and better vigor.
Start Carrot Seed Indoors In Cardboard Tubes
Another trick you can try is starting your carrot seed indoors in cardboard tubes. Usually, carrot seed needs sowing right where the carrots will grow because carrots don’t transplant well.
That’s because the carrot taproot, which is the part of the carrot you eat, gets damaged when a carrot seedling is taken out of the pot and planted in the ground.
When you sow carrot seed in cardboard tubes, you don’t need to take the carrot plant out of the tube when you plant it in your growing bed. You plant the carrot with the tube and the cardboard will decompose over time in the soil.
The cardboard tubes also help to stop cutworms which sever plant stems at the soil line.
For cardboard tubes, just use the inner tubes from toilet rolls or paper towel rolls.
Give Your Carrots Enough Moisture To Grow Well But Don’t Drown Them
Carrots need about 1” of water per week to grow properly.
Carrots that don’t get enough water will be small, misshapen, tough, and bitter.
And as we’ve already discovered, carrots that sit in soil that’s too wet have stunted growth and may rot.
If your soil is a heavy soil with a higher percentage of clay, water deeply once a week, giving 1″ inch” of water. On a clay soil, 1” of water will wet the soil to a depth of 6” and drain through slowly.
If your soil is lighter and drains more freely, water twice a week. On a sandy soil, 1” of water will wet the soil to a depth of 10”.
After you’ve finished watering, take a trowel and dig carefully between your carrot rows to see how far the water has penetrated.
Soil can appear nice and wet on the surface but be bone dry a couple of inches below the surface, which means the root zone won’t get enough water. If your soil is still dry, keep watering and checking to see how far the moisture has penetrated.
The watering guidelines above include rainwater.
Keep a container out in your garden to catch rainfall, so you can estimate how much water your garden beds receive each week.
Cut the top off a 2 liter plastic bottle and use a marker pen and tape measure to mark 1/2 inch (1 cm) intervals along the side. Now you’ve got a basic rain gauge.
When your rain gauge shows less rainfall than your carrots need, make up the shortfall. If the rain gauge shows you’ve had plenty of rain, then there’s no need to give your carrots any more water.
Don’t Overcrowd Your Carrots: Carrots Grown Too Close Together Have Stunted Growth
When your carrots germinate, you must thin the seedlings to make sure that your carrots have room to grow. If carrots grow squashed together, you’ll get shorter carrots. Some will be fat and some will be thin.
Watering before thinning makes seedlings easier to remove and reduces the chance of broken roots.
Thinning carrots releases an aroma that attracts carrot flies and when the tiny carrots break, the aroma is much stronger.
Carrots need thinning twice.
First Carrot Thinning
When your carrot seedlings are around 3″ tall (7 cm), pull out the weakest looking seedlings leaving 3/4″ to 1.5″ (2 cm to 4 cm) between the carrots in the row.
Second Carrot Thinning
Three to four weeks after the first thinning, repeat the process. Once again, pull out the weakest plants, leaving 1.5″ to 3″ (4 cm to 7 cm) between the carrots in the row.
If you’re growing a long slender variety, the smaller spacing will be fine, but leave more space for thicker carrot varieties.
The baby carrots from this thinning don’t need to go to waste because they’re the perfect size for snacking or to add to a salad.
Pests And Diseases Can Cause Carrots To Grow Shorter
The final reason your carrots could be short and fat is because of foliage or root damage.
If disease has damaged your foliage, your carrots won’t get the energy they need to grow well.
And if pests have damaged your carrot roots, they will stop growing or have greatly reduced growth.
Carrots are more susceptible to disease in hot weather and you can reduce disease risk by growing them in the spring or fall.
If you’ve grown carrots that suffered from disease, don’t grow your next crop in the same bed because disease organisms stay in the soil. Avoid growing carrots in that bed for 3 years.
Pests that damage foliage or roots include:
- Carrot Rust Fly
- Carrot Root Fly
- Carrot Weevil
- Flea Beetles
- Leaf Miners
Use Neem oil to make a safe insecticidal spray for your carrots. Neem oil is an organic method of pest control and it works in 3 ways.
- Repels insects
- Disrupts hormones resulting in death
- Suppresses desire to feed, resulting in death
If nematodes have attacked your carrots, use beneficial predatory nematodes to eradicate the destructive ones.
Phew, that was a long read wasn’t it! I hope you’ll be able to use this information to get to the bottom of why your carrots grew short and fat, and to grow a more satisfactory carrot crop next time around.