If you don't have land for a vegetable garden, perhaps you can grow some of your favorites in containers. It can be a challenge and a lot of fun. You're not likely to harvest more than you know what to do with, but what you get will be fresh and tasty. Having grown the food yourself will make it all the more enjoyable.

Most vegetables require at least five hours of full sun. Root vegetables, such as radishes, beets and turnips, can stand more shade than tomatoes, beans, peppers and cucumbers. Leafy vegetables such as lettuce, cabbage, mustard greens and spinach can stand more shade than root vegetables. But they all do best with full sun all day long.

The size of the containers can vary with the number and kinds of plants you want to grow. Six-inch pots are satisfactory for chives. Radishes, onions and small tomatoes such as Tiny Tim will do well in 10-inch pots. Regular-size tomatoes, green beans, squash and eggplant will need five-gallon or larger containers. Half-barrels or wooden tubs can be used for these.

The containers should have drainage holes: Adequate drainage is essential. When the plants are watered, all of the soil in the container should be moistened. If there are no drainage holes, you won't know how much to apply, and it's too much, water accumulated at the bottom and roots die because of root rot.

In most situations the following makes a good container soil: one part good garden soil, one part compost or similar organic matter, and one part sand or vermiculite or perlite.

Soil in containers will dry out faster than the soil in regular gardens. The soil surface and the sides of the containers are all areas of exposure and quick drying.

Small containers may need to be watered two or three times a day, and large containers should be checked at least once a day.

Do not depend on rain, even a heavy one, to provide enough water. The foliage of the plants will often cause the rain to run off without saturating the soil.

As the plants grow the soil will dry out faster, increasing the need for watering more often.

A constant supply of nutrient elements is needed in the confined areas of the containers. It may be best to use a water-soluble fertilizer; used according to directions on the label, these materials will insure rapid growth and good yield by plants in containers. Q&a&q&a&q&a&q&a&q&a&q&a&q&a&q&a Q: My roses have the blackspot disease. I spray them but it does no good. Do you have any suggestions? A: The spores (reproductive bodies) of the blackspot fungus are spread in drops of water, by wind and on passing animals. They germinate best at 79 degrees F. and not at all below 55 or above 91. Almost always spraying prevents a potential infection rather than cures an established one. The spraying should start in the spring and continue weekly until frost, and during rainy weather it may be necessary to spray the plants twice a week. Use benlate, daconil, fore or phaltan, following directions on the label for mix and application. Q: Last year I planted cucumbers; they did fine for three or four weeks, and then all of a sudden they wilted and died. What could have caused it? A: Probably it was the result of bacterial wilt, a disease transmitted to the plants by the feeding of striped cucumber beetles. To prevent it, make weekly applications of sevin, methoxychlor or malathion. It's best to start when young plants are breaking through the soil surface. After blooming starts, make applications late in the day or early in the morning to keep from killing honey bees. Q: What caused my spruce tree to turn brown inside while the outside needles are green and health-looking? A: The inside needles aren't getting enough light. At this point, even if heavy pruning permits better light to reach the interior, most of the brown zone will be unable to respond, and only occasional green shoots will appear. Q: Can cantaloupes and cucumbers be planted side by side without cross-pollinating? A: Cross-pollination will not occur between them because they do not belong to the same species.