Is it time to plant vegetables?

Q. When can I plant my warm season vegetables?

A. The Northwest and West suburbs of Chicago are in USDA Hardiness Zone 5b where the average last frost date is April 28. That means in half of the years, there will be a frost after that date. Vegetables vary in their hardiness and range from very hardy to warm loving. The seed packet will show hardiness information for the variety but here is a short list to use as a guideline:

• Very Hardy (plant four to six weeks before average last frost date): kale, leaf lettuce, onion, leek, pea and spinach seeds; broccoli, Brussels sprouts, cabbage, onion, parsley and potato sets or transplants. Spinach and lettuce seed can even be sprinkled on the snow in late winter to get an early start.

• Frost-tolerant (plant two to three weeks before last frost date): beet, carrot, chard, most herbs, mustard and radish seeds; cauliflower, Chinese cabbage and most herb transplants.

• Tender (plant on average last frost date): snap bean, corn and summer squash seeds; tomato transplants.

• Warm Loving (plant one to two weeks after last frost date): cucumber, muskmelon, okra, pumpkin, winter squash and watermelon seeds; eggplant, pepper and sweet potato transplants. There is no hurry to plant these seeds in cool soil as the seed may rot before it warms up enough to germinate.

Your vegetable garden may act somewhat different than this depending on your microclimate. For example, a south-facing garden against a dark colored brick wall will warm up sooner than the rest of the yard, while a wet, shady spot on the north side will warm up much slower. You can "cheat" the dates a little bit with several tricks. Laying black plastic sheeting on the garden soil in the sun will warm up the soil quicker but will not protect against frost at night. You can use several types of covers to provide some frost protection like cold frames, cloches, hot caps and other covers. A woven white fabric called "floating row cover" can be purchased from the garden center and used over a wire frame to make a tunnel and will provide a few degrees of protection. If you use tomato cages, you can wrap them in clear plastic, which can also provide a few degrees of frost protection. Leave a flap of plastic to use as a roof at night when frost is predicted. You can even cover plants with an old bed sheet on nights where frost is predicted. My favorite device is a plastic tube sometimes called a "wall o water" or "tomato teepee." A cross section resembles an air mattress cut in half to expose its tubes. These tubes are filled with water that soak up the heat during sunny days and slowly release the heat at night providing up to 10 degrees of protection. On sunny days, the top is left open to avoid excess heat buildup and the top can be gathered together like a teepee to keep out the cold air at night. I like to push the season with these devices and plant a few "sacrificial tomatoes" two weeks early. If I succeed, I am eating fresh tomatoes by July 4. If I fail, I still have my main season crop coming at the normal time.

Be aware transplants need to be hardened off before planting outside as they can't tolerate going straight into bright sunlight and cold temperatures. You should start by putting them outside in the shade for a few hours on a nice day and then increase the time and intensity each day for about a week. Then you can plant them in the garden.

- Pete Landwehr

Q. What should I be doing to help my lawn embrace spring?

A. While most folks will agree the past few months have been hard on home gardeners as they wait for signs of spring, it is not surprising the first thing to grab their attention outside is their lawns. First, take care not to trample your lawn if the ground is soft or mushy to avoid compacting the soil. Compacted soils can lead to lawn problems that will require effort to correct.

Once the soil beneath your lawn is solid, you should begin to clean up any winter debris present. Be on the look out for patches of snow mold, which may have formed under snow or matted leaves. Snow mold appears as circles of straw colored patches that keep getting larger, as long as the grass remains wet and cold. Just rake out any infected areas to help them dry out. Then, before the grass begins growing, mow the lawn turf a little shorter than normal to remove dead blades and other small debris trapped in the lawn.

When you notice active growth in the lawn, you may want to consider core aeration. Core aerifying machines make holes in the lawn as they take up plugs of soil about the size of a pencil, and they are available for rental. This activity improves the lawn's environment by incorporating air and water into the soil and by helping break up compaction.

Core aeration also helps break up excessive thatch in lawns. Thatch is dark brown and looks like a woven, tangled mat. It is the layer of living and dead organic matter found between the green shoots and the soil surface. When the layer of thatch present is less than half-inch thick, there is no need to worry. Excessive thatch, on the other hand, can create a desirable home for many lawn diseases and pests.

If your lawn looks a little thin here and there, you may want to overseed with a mix of perennial grasses blended for lawns receiving high amounts of sun, high shade or a combination of sun and shade. Evenly spread seed over the planting area. To ensure you are successful in re-establishing turf, use a rake to lightly mix the seed into the upper quarter-inch of soil. Alternately, you may top dress the area with a thin sprinkling of soil. This allows seed to have the necessary contact with soil for germination.

To conserve water for seed germination, you may want to apply a thin layer of straw, which will gradually decompose as the grass seedlings emerge. Providing adequate water to the seeded area is important for seed germination. Once your seeds are mixed with the soil, water lightly and frequently to create a moist environment. When the grass blades mature, you can water less frequently, but increase the duration to encourage strong root growth.

Turf grass maintenance is an ongoing process, but it is an important part of being able to enjoy a quality lawn.

- Mary Moisand

• Provided by Master gardeners through the Master Gardener Answer Desk, Friendship Park Conservatory, Des Plaines. Call (847) 298-3502 or email northcookmg@gmail.com.