Q. Can you recommend fragrant plants to grow in big pots on my new deck? I am thinking of a rose, jasmine, orange trees and wisteria.

Q. Can you recommend fragrant plants to grow in big pots on my new deck? I am thinking of a rose, jasmine, orange trees and wisteria.

A. Citrus plants have flowers that are sweetly fragrant for a long period. The calamondin orange is known for its abundance of sweet flowers from late summer to early autumn. Add a few tuberose bulbs in each large container. They don't take up much space and provide a powerful fragrance.

Orange jasmine, Murraya paniculata, is one of the best fragrant plants for containers. Also think of plants with aromatic foliage. Scented leaf geraniums and pineapple sage are must-haves.

When the weather grows cooler in autumn, consider planting some fragrant pansies or violas and mix them with sweet alyssum and wallflowers.

If there is a prolonged autumn, they will provide fragrance well into November.

Most roses suited to container cultivation are bred for their toughness but typically aren't fragrant. The wisteria is a sprawling vine that would not be happy in a container and even with constant pruning could take years to flower.

Q. I had poor luck getting my tomato seedlings to grow with vigor this spring. I kept them warm, the room humidified and the seedlings growing under two fluorescent bulbs, but they stalled. Would fertilizer help, and how often should it be applied?

A. The seedlings may have been starved for light. Regular fluorescent lamps give off light that is less intense than lamps designed specifically for plants. Plants use red and blue light for photosynthesis, and you can get fluorescent tubes that provide more red and blue light than standard tubes. They must be placed close to the seedlings, no farther than six inches.

A high-intensity discharge lamp imparts a lot of light, but concentrated in the red spectrum. It is so bright that it must be placed about three feet from the leaf surface. The best indoor lights for starting seeds have a combination of fluorescent tubes that boost the amount of light in the blue wavelength and a rather small high-intensity discharge lamp.

Tomatoes can be successfully grown from seed outdoors in a well-prepared seedbed. Simply plant three or four seeds in each location you wish to grow a tomato plant. Thin the seedlings to one or two when they have grown their second set of true leaves. In most cases, your harvest may be only slightly delayed because transplants don't grow until night temperatures are warm. This is particularly true for heirloom varieties that tend to be indeterminate plants that fruit later than most tomatoes.

You can plant tomato seeds as late as early July for an October harvest. Be sure that the soil is well prepared, and water the seeds weekly to get them off to a good start. Late plantings may avoid some of the foliar fungal diseases associated with wet spring weather.

Scott Aker is a horticulturist at the U.S. National Arboretum.