10 Hardest Vegetables to Grow and Maintain

Cauliflower, a part of the brassica family, which includes broccoli and cabbage, can be a difficult vegetable to grow. "Cauliflower is a little tricky because it has a long growing season, and it prefers it a little cool," says Bartley. Cauliflower doesn't like it too hot or too cold, so you have to start it early enough to have it mature by the hot temperatures of summer, but late enough so that it doesn't get too cold [source: University of Illinois, Urban Extension]. Its ideal temperature range for growing is about 65 to 80 degrees Fahrenheit (18 to 26.5 degrees Celsius) [source: Bradley & Courtier]. In order to get a white-headed beauty, cauliflower must have the right temperature, but most plants must also be blanched, or have the stalks bent so that the outer leaves come up and over the top of the head, covering it [source: The Editors of Garden Way Publishing]. The leaves must be tied and stay this way until the head has matured.

Along with correct growing conditions, cauliflower is also susceptible to bugs, such as cabbage worms and disease.

Crunchy, green stalks characterize mature celery, yet for some growers, it can be difficult to get celery to that point. Celery requires a lot of moisture, so it should be planted in a soil that can hold water well [sources: Spencer and The Editors of the Garden Way Publishing]. The moisture requirements can be a burden on some gardeners who might not be used to consistent watering. The plant also has a long growing season of about 120 to 180 days from seed to harvest [source: Bartley]. During the growing season, celery also needs cooler temperatures, making it a difficult plant to grow during the summer in the Midwest or South.

As an alternative to celery, Bartley recommends cutting celery, which has the celery flavor, but is actually grown for its leaves instead of its stalks.

Farmers across the nation grow corn, yet strategic choices are integral to producing a successful crop. When selecting the varieties you're going to plant, be careful about planting certain ones, such as super-sweet and sugar-enhanced plants, together. These can cross pollinate and produce ears with field corn kernels that don't taste that good [source: Coolong and Bradley & Courtier].

You'll also need a good amount of space and correct placement to grow corn properly. "Typically, corn is wind-pollinated," says Timothy Coolong, Ph.D., extension vegetable specialist for the University of Kentucky. "The pollen comes off the tassel at the top of the plant and then goes down to the silks that come off the ear of the corn; that's how it's pollinated."

Due to wind pollination, the corn crop needs to be planted in a square shape with at least 15 to 20 plants [source: Coolong and Bradley & Courtier].

If you're a fan of eggplant parmesan, then you might want to grow the deep purple vegetable in your garden. While eggplants are very sensitive to temperature fluctuations, one of their main problems is pests. "My plants (eggplants) usually look like the leaves have been shot with a pellet gun with tiny holes everywhere," says Bartley. "The holes are from the flea beetle."

The flea beetle, along with other pests, can be combated by row covers as well as pesticides [source: Bartley and Coolong]. Organic gardeners can have an especially difficult time with these plants. "They have a lot of insect pests," says Timothy Coolong, Ph.D., extension vegetable specialist for the University of Kentucky. "If someone doesn't want to spray a lot of pesticides, [eggplants are] fairly challenging to grow."

Leaf lettuce can be fairly easy to grow. Yet, if you want one of those nice specimens you can get at the grocery, you're going to have more of a challenge. "If you want a nice attractive head like they sell in the stores, it needs uniform watering and if you have temperature fluctuations, in lettuces, you can have this process called bolting," says Timothy Coolong, Ph.D., extension vegetable specialist for the University of Kentucky.

Bolting is a premature flowering or seed formation of the plant which can make it taste bad [source: Bradley & Courtier, The Editors of Garden Way Publishing]. "I would say that head lettuce (iceberg) has been hardest for me to grow because of the precise sun/shade needs that keep it from bolting," says Jonathan Mueller, landscape architect with Landmark.

Different plants can have different criteria, yet warm temperatures and longer day length can increase the chances for bolting in lettuces [source: Colorado State University Extension and Ellis].

A favorite with rabbits, carrots are a root vegetable that can require special care. The main challenge for carrots is soil preparation. According to Jonathan Mueller, landscape architect with Landmark, carrots don't do well without at least 6 inches (15.24 centimeters) of soil that's well tilled and loosened. You also want to be careful about the type of soil that you choose to use. "If there are any pebbles or anything in the soil, the roots will grow around those pebbles so you'll get very misshapen roots," says Timothy Coolong, Ph.D., extension vegetable specialist for the University of Kentucky.

The type of soil is also crucial. Carrots are very difficult to grow in clay soils. Mineral soils work well, but humus is a better bet. If you don't have the right kind of soil in your yard, try growing carrots in raised beds. This will allow you to have a good deal of oversight related to the soil composition and ground moisture.

While not bright orange like carrots, muskmelons do have a pale orange fruit surrounded by a tan outer rind. These melons have a long growing season and also require a good deal of space, about 4 to 6 feet (1.2 to 1.8 meters) between each plant [source: Bradley & Courtier]. Along with spacing and timing, muskmelons also have specific climate requirements. "More than anything else, I think you need the right microclimate for melons," says Jonathan Mueller, landscape architect with Landmark.

Melons need warm days and nights along with warm soil to grow successfully. These requirements can be difficult to meet in northern climates.

Once you have your melons growing, you still have to be careful about disease susceptibility and pests. Diseases such as fusarium wilt and pests such as cucumber beetles can ruin a crop of juicy melons.

Onions may make you cry when you cut them, but growing them can also get a beginner upset if proper growing information isn't made clear. Picking the correct onion to grow in your garden is where many beginning gardeners can get into trouble. Onions are particularly sensitive to the amount of daylight they receive. There are different varieties of onions that require shorter days, about 12 hours per day, and others that require longer days, about 13 to 16 hours of daylight [source Coolong and Ellis]. This means that picking the right onion and planting it during the right time of year is critical to a good crop.

Sweet potatoes, or yams, were originally a tropical plant, which explains its need for warmth. Sweet potatoes need a long, hot growing season of usually more than 100 days of hot weather [source: Ellis]. This plant also doesn't like cold soil. For these reasons, sweet potatoes do better in southern climates and can be tricky for areas that have cold nights during the growing season. Northern growers might have a better chance at getting a successful crop by growing the plants in raised beds with row covers to protect the seedlings from the cold.

Artichokes can be a challenge for beginner gardeners because of their climate requirements and a certain pest. The globe artichoke is actually a native of the Mediterranean. They're grown as perennials in that part of the world. Due to similar climate conditions, artichokes work well as perennials in northern California, but may be difficult to grow as perennials in other areas of the nation. Since artichokes like moderate conditions, grow them as annuals in cold winter and hot summer areas.

Along with proper temperatures, artichokes also have problems with aphids. This green plant-sucking insect can stunt the leaves and can also spread viruses that can hurt the plant.

Whether you're trying to grow artichokes or carrots, one of the first steps to successfully growing vegetables is researching the plants you want to grow and learning what their specific needs are so that you can make the best decisions for your garden.