Vegetables Top Ten Questions

I would like to plant asparagus. What do I need to know to grow them?

Asparagus is a perennial plant that comes back every year and one of the earliest producing vegetables in the spring. There are both female and male plants. As a general rule, female plants produce larger spears and male plants produce larger amounts of smaller diameter, more uniform spears. Most of the newer hybrids are all male plants.

Choose your planting spot carefully, as a bed of asparagus can last at least 15 years. Plant them in a fertile, sunny, well-drained site with good moisture. Medium-textured sandy loam to loam soils will usually produce the highest yields. Asparagus plants have a deep root system that can go down at least six feet, so avoid planting them in shallow soils or those with wet soil conditions. They grow best in a soil with a pH of 6.5-7.0, so it would be a good idea to get your soil tested to see if you need to amend it.

Most people plant asparagus from purchased crowns because it is easier and you get a crop one year earlier than if you plant them from seed. Try to purchase crowns that are one year old. Plant them with the crown buds upward in a trench or furrow about 12-18 inches apart and 6-8 inches deep; then immediately cover them with 2-3 inches of soil to keep them from drying out. Continue to add soil as the shoots emerge until the furrow is filled by the end of the first growing season. Asparagus crowns will continue to enlarge both vertically and horizontally over several years so planting at the appropriate depth is critical. It takes three years to develop a large root system and maximum fern growth to support future spear production. It is important to make sure your plants have adequate soil moisture. Inadequate soil moisture during fern development can cause significant reduction in the next spring’s spear production and negatively affect quality and yield.

To harvest asparagus, leave the old ferns until spring before chopping or mowing them. After spears appear, harvest when they are 6-8 inches long. Snap spears off at the soil surface. Do not cut the spears because of the danger of damaging neighboring spears that have not yet emerged. Allow spears remaining after July 1st to develop into ferns.

I have two pepper questions. First, when can I plant peppers? Second, my teenage son would like to grow some hot peppers - what do you recommend?

Peppers are heat-loving vegetables that need a long, frost-free season and full sun. If you started your peppers from seeds you will need to wait until they are about five inches tall and six to eight weeks old. Then, start hardening them off so that they will adapt when you transplant them outdoors. Otherwise, buy plants at a local nursery and plant them in a sunny area after all danger of frost has passed and the soil has warmed.

Peppers can be sweet or hot and come in all colors (green, yellow, orange, red, and purple). Sweet peppers include banana, bell, cherry and pimiento. Hot peppers include ancho, chile, habanero, jalapeno, and serrano.

I would like to plant rhubarb this year. Is there a recommended variety I should purchase? How should I plant it for best results?

Rhubarb is a perennial vegetable that grows well in Minnesota gardens. It is hardy to USDA Zone 4, but many gardeners successfully grow it in Zone 3. Varieties differ in color and levels of tartness and fibrousness. Color doesn’t affect flavor. Most people prefer the red varieties, but the green ones are usually more productive. The red varieties tend to be more appealing for making pies because the color of the filling looks better than the grayish color of the cooked green varieties. Canada Red is a red cultivar that typically produces shorter, more slender stalks than other varieties and is tender and very sweet. It usually produces few seed stalks. Cherry Red, a vigorous producer, has long, thick stalks that are a rich red inside and out. It is tender, juicy, and sweet. Victoria produces medium-sized stalks of excellent quality and good flavor. There can be some variation in stalk color, but in general they are light green with pink speckling, especially at the bottom of the stalk.

Rhubarb gets quite large, so plant your purchased crown piece in a three-foot by three-foot growing area. Plant it so the buds are about two inches below the soil surface. Rhubarb performs best in well-drained, organic-rich soil, in full sun. Don’t harvest any stalks the first year – wait until the second season so the plant has a chance to get established.

Last year something attacked and killed my summer and winter squash. Can I do something to prevent it from happening this year?

It sounds like the very damaging moth called the squash vine borer. They commonly attack summer squash, winter squash, and pumpkins. The adult borer is approximately ½ inch long, has an orange abdomen with black dots, and looks like a wasp. The larvae are white or cream-colored with brown heads and are approximately one inch long. Beginning in late June or early July the adults emerge from cocoons in the ground then lay eggs at the base of susceptible plants. About one week later the eggs hatch and the larvae start feeding on stems and continue for 4-6 weeks. The first symptom is wilting of the affected plant and you may see holes near the base of the plant filled with moist greenish or orange material that looks like sawdust. Squash vine borers are difficult to prevent and manage. They make a buzzing sound, fly around, and are easy to spot, so you may want to start watching out for them at the end of June. They are attracted to yellow so you could set out yellow-colored pans of water, which they will fly into and drown. It is important to pull up and destroy any plants killed by squash vine borer. You could plant a new crop of squash at the beginning of July because they will mature when the adult borers are finished laying eggs. Another option is to plant vine crops that are usually not affected by the borer, such as: melons, cucumbers, or butternut squash.

I am growing rutabagas, turnips and parsnips for the first time and am wondering when to harvest them and how to store them.

You should have healthy winter meals from these nutrient-rich root crops. Turnips can be picked at any time, usually when they are 2-2 ½ inches in diameter. Rutabagas and parsnips should be left in the ground until after two or three light frosts. Frost turns their starches into sugars and their flavors improve. All three should have their tops trimmed down to about one inch. They should be washed clean and any bruised vegetables used as soon as possible. Healthy vegetables should be stored in cool, dark conditions, ideally at between 35- and 40-degrees F and at 95% humidity. Home storage conditions matching these may be difficult to provide, so approximate them as closely as possible. Their storage life will vary from two to five months depending upon storage conditions. Although you may find rutabagas, turnips and parsnips that have been dipped in wax in stores, the University of Minnesota advises against doing so.

I planted Brussels sprouts for the first time this year, how do I know when to harvest them?

To speed up the development of the sprouts, remove the growing tip about three weeks before harvest. Do not pluck off the leaves of the plant as it is growing, the more leaves on the plant the more energy they produce and the bigger the sprouts will grow. Harvest the sprouts from the bottom up when there are about an inch in diameter and firm. The cooler temperatures, even a light frost result in better flavor.

Are the pumpkins and gourds that are for sale around Halloween edible?

There are two species of pumpkins, Cucurbita pepo are usually the jack o’lanterns and some pie pumpkins and Cucurbita maxima are the giant ones grown for competition and decoration. People generally do not eat the pumpkins grown for jack o’lanterns because they are stringy and tasteless; however, the seeds are good roasted. There are three species of edible winter squash: Cucurbita pepo is the acorn and spaghetti squash, Cucurbita moshata is the butternut type, and Cucurbita maxima include the hubbard, kaboch, turban, and buttercup types.

My leaf lettuce is starting to taste somewhat bitter and stalks are shooting up. Should I pull it out?

Lettuce is a cool weather vegetable that grows best at 60-65 ° F. Leaf lettuce grows quickly and is the easiest type of lettuce to grow. During the heat of July leaf lettuce and spinach tend to bolt (go to seed) and taste bitter. When it bolts, pull it out of your garden and replace it with broccoli, cabbage, or cauliflower for a fall harvest.

With all the rain we’ve been getting, I’ve noticed some of my tomatoes now have a black spot at the end of the tomato. What is it and is there anything I can do?

It sounds like blossom-end rot, which is a common tomato disorder and often occurs when we receive large amounts of rain. Blossom-end rot is caused by a calcium deficiency in the plant. Three factors can affect the plant’s ability to take up calcium: fluctuations in soil moisture, heavy applications of nitrogen fertilizer, and injury to roots. You can minimize blossom-end rot by consistency in watering, fertilizing the soil based on a soil test, and avoiding root injury.

I planted honeydew melons, cantaloupe and watermelons in my vegetable garden and was wondering how I tell when they are ripe and ready to harvest.

Cantaloupe requires 35-45 days to mature from flowering, depending on the temperature. If you are using plastic mulch (which warms the soil, conserves water, helps to control weeds, allows earlier planting and maturity, and reduces ground rot of the fruit) harvesting could be 7-14 days earlier than if you are growing melons on bare ground. As your cantaloupes ripen reduce your watering amount to improve flavor. Even watering is very important, especially in the last two weeks of growth. When a cantaloupe is almost ripe, too much water will dilute the sugars and dull the flavor of the melons. In addition, excessive watering at this stage can cause the fruits to split.

As the fruit matures the skin surface netting gets coarse and rough, the background color of the fruit turns from green to yellow, the surface color becomes dull, and the tendrils near the fruit on the stem dry and turn brown. Harvest the fruits by twisting the fruit to separate them from the vine. Do not wait for the melons to separate from the vine on their own. At full maturity and peak flavor, the stem breaks (slips) away from the vine easily. This stage is called “full slip.” Pick melons as they ripen because they will not all ripen at the same time. Commercial melons are harvested at 1/2 to 3/4 slip" to reduce shipping damage. This removes the fruit before it has reached maximum sugar content, and sugar content will not increase after harvest. If you find melons for sale at a farmer’s market or store that have little stubs of vine sticking out of them, they were harvested too early and probably won't be very sweet. One of the biggest advantages of growing your own melons, is the opportunity to harvest at maximum ripeness.

Determining when watermelon and honeydew melons are ripe is a little more difficult as they typically do not slip from the vine. There are some indicators you can use to determine ripeness: tendrils near the fruit stem have become brown and dry; the fruit surface has become rough to the touch and the fruit color turned dull; the bottom of the watermelon, where it lies on the soil, has changed from a light green to a yellowish color. To make sure a honeydew melon is ripe, place the melon in a bag with ripening apples or tomatoes. The latter will release ethylene gas, which will complete the ripening process. Select melon varieties that will ripen under your conditions. Short season types ripen between 65 and 75 days. Full season types ripen around 85 days.