Home > Plant Talk > Sunlight, soils and vegetable yields

Sunlight, soils and vegetable yields

 feed icon
Wednesday, May 7, 2008

Q. I started preparing my vegetable garden for planting this past weekend. At one time, the garden was in full sun. Now, it is shaded by midafternoon. I've never had great yields with my clay soils and was debating moving the whole garden to the southern side of the house, where I get full sun. How much sunlight do I need for most vegetables? Should I bother to move the garden? -- David M., Carteret

A. If you get full sun until midafternoon, you can still grow a great variety of vegetables. Many of the sun-loving vegetables such as tomatoes, peppers, eggplant, cucumbers, melons, squash, corn and beans grow best with eight hours to 10 hours of direct sunlight. You can grow these vegetables with as little as six hours or seven hours of direct sun, but they will not yield as well.

It sounds like you really need to improve the heavy clay soils in your garden. If you have access to compost, till 3 inches of well-rotted compost or peat moss into the top 12 inches of soil to improve conditions for roots. Test the soil and adjust the pH to 6 to 6.5 (which is good for most vegetables).

Gardens that are shaded in the afternoon are often ideal for growing leafy vegetables like lettuce, spinach, Swiss chard, kale, and collards, as well as root crops such as beets, carrots, turnips and radishes. These vegetables will grow in as little as four hours to five hours of direct sunlight. More sunlight will increase yields of root crops.

If you don't have the energy or time to create a large vegetable bed, consider growing some vegetables in large containers on the south side of your property. Many vegetable varieties were developed for container growth and small garden spaces. For many sun-loving vegetables such as tomatoes, peppers, eggplant and cucumbers, a 3- to 5-gallon container will do. Smaller fruited varieties of tomatoes, peppers and eggplants can often be grown successfully in moderate to large containers. Make sure containers drain properly and check daily for watering needs.

I have grown many vegetable varieties in large containers with stakes and small cages or trellises to keep plants upright and supported. I have grown 'bush celebrity' and 'Sungold' tomatoes, as well as many of the hot pepper varieties in medium to large pots.

Q. What are the best heirloom tomatoes and what are your favorites? Any tricks to growing heirlooms? I had a great number of cracked and diseased tomatoes last year that I could not harvest.
-- Katie, Bordentown

A. Heirlooms can sometimes have more disease and pest problems, as well as fruit-cracking, in comparison to hybrids.

The traditional definition for an heirloom plant is one that has been passed down from one generation to another. By saving seeds of the fruit, the progeny will have the same characteristics as the parent.

Hybrid plants have two different parents and the progeny from a hybrid plant will not consistently represent the characteristics of the hybrid. Hybrids also display what is called "hybrid vigor," meaning that these plants can often tolerate increased environmental stress and exhibit resistance to a variety of disease and pest problems.

Here are some tips for growing heirlooms successfully:

-- Select varieties that you like, but will also perform best in your particular garden. What works in one garden may not work in another. That is why you need to keep a garden log of plant names and locations as well as pest problems, culture, controls used, yield and flavor to determine what will work best for you.

-- Provide an organic, rich soil and do not overfertilize. Mix 4 inches of well-rotted compost or peat moss into the top 12 inches of soil with a shovel or roto-tiller before planting. I like to add an inch or two of dried, composted manure into beds for tomatoes, peppers, eggplant and cucumbers. Avoid using manures around leafy vegetables or root crops. These natural sources of nutrients will encourage proper nutrient uptake, water retention and aeration for roots.

-- It is often wise to plant heirloom tomatoes and peppers on raised beds to control moisture and prevent water-logged soils. Heirlooms are more sensitive to root rot diseases. I grow my tomatoes and peppers in metal cages or with tomato stakes to keep plants upright.

-- Vertical growth and proper spacing of heirlooms at 30 inches to 36 inches apart will provide better air circulation and sun penetration for plants. This practice can help to reduce foliar diseases.

-- Water heirlooms at the base and try not to get the leaves wet. This can help reduce the incidence of foliar diseases like early blight on tomatoes. Keep heirlooms evenly moist throughout the season to reduce the incidence of fruit-cracking. Harvest tomatoes as soon as they are ripe and in some cases, once they begin to show significant color, you can continue to ripen them inside in a paper bag.

Some of my favorite heirloom tomatoes include 'Mortgage Lifter,' 'Aunt Ruby's German Green' and 'Isis Candy.' My overall hybrid favorite varieties are 'Ramapo,' 'Jet Star' and 'Celebrity,' for slicing tomatoes. 'Sungold' cherry tomatoes are my overall favorite for salads and eating off the vine.