5 Challenging Vegetables to Grow

carrot harvest

The Spruce / K. Dave

Vegetable gardening should be an enjoyable and rewarding task. There's nothing like picking your first homegrown tomato or watching a pumpkin fill out. Most vegetables are pretty straightforward to grow. You plant a seed or seedling, keep it watered, and it eventually matures into something delicious. Other vegetables take a bit more finesse.

The five vegetables discussed here all pose a different challenge to gardeners. Some never seem to fill out, and others grow but don't taste good.

Common Carrot Problems and Solutions

Carrots can be easy to grow, or they can give you endless grief. Some issues are easy to take care of, such as green tops or soil that's too hard for the tiny seedlings to push through. Keeping up with weeding, amending nutrient balance, establishing proper spacing, observing soil temperature, and keeping watering consistent all take care of many problems, such as skinny carrots, cracked roots, or those growing deformed. The major carrot issues and their solutions include:

  • The seed never germinates: Carrots won't break through encrusted soil. Keep the soil moist but not soaking wet. Don't let it dry out and crust over. An old trick for keeping the soil loose is to plant radish seeds right up next to the row of carrots. The radishes will germinate first and keep the soil loose. Another trick is to cover the seed with sand or vermiculite. These won't make as hard of a coating as garden soil.
  • Plants go right to flower and seed and never develop roots: Don't put your seed out too early. Carrots are biennials, and low temperatures make them think they've already gone through winter and it's time to go to seed.
  • The shoulders of the carrots are green and bitter: This is an easy one to fix. Cover the whole root with soil. Exposure to sunlight will cause them to turn green at the top from developing chlorophyll.
  • You get skinny carrots: This usually is caused by nearby weeds that compete for nutrients and water. Keep the area weed-free.
  • They have short, stumpy roots: The soil is probably too warm. If the soil heats to more than 70 F, the roots become stunted. Use mulch and keep the soil well-watered during hot spells to keep carrots cool.
  • They have deformed roots: Forked or bent carrots are the result of something getting in the way of the developing roots. The soil could be too hard for them to grow through, they may have hit a rock, or maybe there's another carrot planted too closely. Before you plant, till the soil a foot down to soften it up. And thin your carrots early. Another problem could be root-knot nematodes. If that's the case, you will need to solarize the soil by covering it with clear plastic and letting it fry in the summer sun. Definitely remove the carrots before you cover it.
  • The roots crack down the side: Cracking is caused by inconsistent watering. Carrots that are left dry for a period and then given a lot of water will swell up and crack. Give them water every week, and mulch the area so the soil remains moist. Also, harvest when the roots are mature. Leaving them too long is another cause of cracking.
  • The carrots have lots of tiny roots all over them: This is caused by too much nitrogen. Don't overfeed your carrots, and don't use a high-nitrogen fertilizer.
  • The carrots have bitterness: Carrots like cool soil. If the temperature never cools off at night to at least somewhere near 60 F, they will use up some of their stored sugars to acclimate. Keep the soil moist and mulched and maybe hold off planting carrots in the middle of summer.

Common Celery Problems and Solutions

The flavor of fresh celery is more intense than the bunches you get at the grocery store. Some people love it, and others find it overpowering. Many gardeners consider celery difficult to grow. They may end up with more leaves than stalks, plants that bolt too early; the death of the center of the plant; or cracked, bitter, or tough stalks. Cold temperatures are often the culprit, or you might need to amend your soil. A soil test will tell you if you have a nutrient deficiency that is the culprit. Solutions to major celery issues include:

  • The celery has lots of leaves but no stalks: This happens when the temperature swings back and forth in early spring. Don't put your celery plants out when nighttime temperatures are still slipping back into 40 F or colder.
  • The plants bolt to seed: Again, cold temperatures are to blame. A prolonged period of temperatures below about 55 F makes the celery think it's time to set seed. If you've already planted, cover your celery with a row cover when the temperature dips.
  • The inner stalks and leaves die: If they turn a dark color, it's blackheart disorder, and a lack of calcium is the culprit. Insufficient calcium inhibits the uptake of water by the plant. Water it regularly and mulch. Have your soil tested, and if calcium is the problem, add some lime and try growing celery varieties that are resistant to blackheart, such as 'Emerald' and 'Golden Pascal.'
  • The celery has cracked, brittle stalks: This problem is caused by a boron deficiency. A balanced fertilizer should help, and you can also plant resistant varieties such as 'Golden Self-Blanching' and 'Giant Pascal.'
  • It has bitter, tough stalks: Cultural problems add up and cause tough, bitter celery. It's usually a combination of hot weather, dry soil, and a lack of nutrients. Keep your celery watered and mulched, feed the soil with organic matter, if necessary, and plant it so that your celery will mature when the weather is cool in the fall.

If growing celery trumps you, you may have more success resprouting the base of a celery bunch, after you eat the stalks, though you may get more leaves than anything else doing this. As an alternative, consider growing celeriac, or celery root, instead. It has good flavor and is much, much easier to grow.

celery growing
The Spruce / K. Dave 

Common Cauliflower Problems and Solutions

Cauliflower may be known as a cool-season vegetable, but don't be in a rush to put out seedlings. Mature plants can handle cold, but cauliflower seedlings actually like temperatures around 60 F. Cauliflower is a biennial, and if the plants experience enough cold weather early in the season, when the weather eventually warms, it will think it has gone through winter and is in its second growing season. Hold off setting out seedlings until at least three weeks before your last expected frost date and have the row covers handy, just in case.

But bolting is the least of the problems facing cauliflower growers. It's getting those beautiful curd heads that give them the most trouble, which can be caused by weather or soil that needs amending. Cauliflower head issues and their solutions include:

  • It has a tiny, button-sized head: Again it is fluctuating temperatures that cause tiny cauliflower heads. There's actually a term for it: "buttoning." You can't correct it after it happens, but you can avoid it by waiting until the weather moderates before planting.
  • It has browning curds: Discolored curds are a sign of boron deficiency, which is more common in alkaline soils. Test your soil pH and add sulfur, if necessary. You should get enough boron by using a fertilizer that says it has trace minerals.
  • It has loose heads with a yellow tint: Yellowing heads signal too much sun. Use those large cauliflower leaves to shield the heads, and tie them in place. Cauliflower grown in the fall usually does not have this problem.

Common Head Lettuce Problems and Solutions

Leaf lettuce is fairly easy to grow as a cut-and-come-again crop. Head lettuce can be a good deal more challenging. You have to allow a lot more time for lettuce to mature and form a head. While it's getting there, the weather can foil your best attempts.

Lettuce reacts to both heat and day length. Prolonged hot weather not only causes lettuce to want to bolt to seed, but it also makes the existing leaves bitter. Keeping your lettuce watered and partially shaded can help offset the effects of heat.

The length of sunlight is much harder to control, and this is what actually triggers lettuce to send up flower stalks and go to seed. Setting out seedlings as early as possible in the spring (and hoping for a long, cool season) is one workaround.

You could also start new plants in mid-summer for a fall planting. (In warm climates, you would start seeds in fall for a winter planting.) Starting the seeds in containers and then transplanting them in a shady spot generally works better than trying to direct sow in hot summer soil.

growing lettuce
The Spruce / K. Dave 

A Few More Tips

Transplant lettuce seedlings in the late afternoon and water them in well. This gives them the whole evening and night to settle in before the sun shines on them.

Add a lot of organic matter to the soil, to retain moisture, and give the plant regular doses of high-nitrogen fertilizer, such as bone meal or fish emulsion, to encourage speedy growth

Common Melon Problems and Solutions

Most melons grow on sprawling, space-hogging vines, and many gardeners shy away from growing them for that reason. That's a shame because fresh melons can be incredibly sweet and juicy, and your variety of options are enormous. However, flavorful melons are not the easiest things to grow. From plants with no fruits to bland-tasting fruits, there's a lot that can go wrong. Help your pollination (and thus fruit production) along by companion planting flowers that will attract more insects to the garden, and keeping the plants consistently watered—not too wet or dry. These two fixes can go a long way toward solving a lot of these problems:

  • You have lots of flowers but no fruits: This is a common complaint of both melons and squash. Both plants have separate male and female blossoms. The male blossoms tend to start blooming first, and they wither and fall of the plant. After the female flowers start opening, the male flowers will still wither and drop, but the female flowers should develop embryos where the flower attaches to the stem. Even though these embryos appear, they may not make it to maturity. The female flowers need to be pollinated multiple times, and each is open for only one day. That means there have to be enough pollinators in the garden to get the job done. Rain, wind, and pesticides can all keep pollinators away.
  • You have misshapen fruits: Oddly shaped fruits happen for a couple of reasons. The first is inadequate pollination, while another is uneven watering. Melons like even moisture while the fruits are developing. You can't let them sit in hot, dry soil and then try to make it up with a deluge. Don't keep the soil dripping wet, but make sure it doesn't sit dry for more than a day.
  • You get bitter fruits: Bitter or bland melons can be the most frustrating problem because you don't know about it until you bite in. Bitterness is caused by temperature swings, especially heat spells. Keep your soil mulched and watered to prevent stressing your melon plants. Amending with organic matter prior to planting will also help conserve moisture.
  • You receive a few fruits per plant: This could just be the type of melon you are growing. They don't all load up with fruits. Other possible causes are planting seeds or seedlings too closely together, resulting in the plants competing for water, sun, and nutrients. It could also be from planting them too far apart, causing poor pollination.
growing melons
The Spruce / K. Dave