The same potting soil can be used over several seasons, along as fertilizer is added to restore nutrients and the soil doesn't become to compacted, destroying air pockets that help drainage. If soil becomes too dense, incorporate perlite or vermiculite.

Leaf-footed bugs create yellow spots on ripe tomatoes by piercing tissue with needle-like mouthparts and sucking out the juices.  

The same potting soil can be used over several seasons, along as fertilizer is added to restore nutrients and the soil doesn't become to compacted, destroying air pockets that help drainage. If soil becomes too dense, incorporate perlite or vermiculite.

Garden columnist Dan Gill answers readers' questions each week. To send a question, email Gill at gnogardening@agcenter.lsu.edu. 

My vegetable garden is all in containers. I use a commercial potting soil, and it has worked well. During the summer, I fertilize with a commercial soluble fertilizer as I water. I don’t want to throw away the old potting soil each year and purchase new potting soil to replace it. My question is — how can I replace the nutrients lost during the previous growing season so I can reuse the potting soil I used in the pots the year before? — Ned Holtz

Fertilizers replace the nutrients lost from potting soil due to uptake by the plant or leaching. By regularly applying a soluble fertilizer, you are already taking care of replacing lost nutrients. If you follow your standard fertilizer routine each year, the soil will continue to provide the minerals a vegetable plant needs to be healthy and produce abundantly.

The more important issue with old potting mixes concerns their structure. Over time, the organic components of the mix (peat moss, composted bark, and various other components) decay, break down and lose their structure. This can cause the potting mix to become denser and more compacted with fewer air spaces and reduced drainage.

The decaying of the organic matter also leads to loss of volume. This is also why potting mixes in pots can seem to shrink over time. It may take more than one year for the potting mix to lose its structure, so evaluate it each spring before planting and see how it looks.

If the mix still looks good, you don't have to do anything. If it has gotten too dense and heavy, a solution to this problem is to mix the old potting mix with new potting mix, generally about half and half. Sometimes I save money and add sifted homemade compost instead of new potting soil — about half compost and half potting soil.

Another option is to incorporate perlite or vermiculite into the old potting soil. Mixing one-third perlite or vermiculite to two-thirds old potting soil is a great way to lighten the old soil, ensuring that it is porous and drains well.

Something is eating holes in my tomatoes. The holes are round and about 1/2-inch across. I’m also seeing holes in the leaves of my squash and tomatoes. What do you think is causing this damage, and what is the best way to control this pest? — Tilda Coleman

The tomato fruit are being damaged by a caterpillar called the tomato fruitworm. Caterpillars also are the likely culprits chewing holes in the leaves of the tomatoes and squash.

Caterpillars are one of the most common insect pests we must deal with in vegetable gardens, and there are a wide variety of effective insecticides. Control should begin at the first sign of damage and continue regularly while the crop is in the garden. It often takes multiple insecticide applications to get a caterpillar population under control.

When you see caterpillars on vegetable plants, handpick and dispose of as many as you can find. After you finish hand picking, you may decide to spray an insecticide to ensure good control.

When choosing an insecticide, you do not need to know what kind of caterpillar you have. We use the same insecticides for caterpillars in general. Be sure to spray thoroughly under the leaves. An organic option is spinosad (various brands). Another organic option is BT (Dipel, Thuricide and other brands). But it must be consumed and is slower acting.

If you are seeing a high population and lots of damage, faster control is desirable. Permethrin or bifenthrin are pyrethroid insecticides that kill on contact and provide the fastest knock down with good residual action.

Finally, carbaryl (Sevin, Carbaryl) is a classic insecticide that has been used for generations to control caterpillars on vegetables. It is a stomach poison that must be consumed to work. Sprays are more effective than dusts.

HOT UPDATES: Most of the cool-season vegetables still lingering in the garden should be cleared out this month. As cool-season crops finish and are removed, rework beds and plant heat-tolerant vegetables (okra, peanuts, Southern peas) for production during the summer.

COMPOST CARE: During dry weather, don’t forget to occasionally water your compost pile to keep it moist. Dry organic matter will not break down. Sometimes it is helpful to shove the hose into the compost pile to make sure water reaches the inner parts.

Leaf-footed bugs create yellow spots on ripe tomatoes by piercing tissue with needle-like mouthparts and sucking out the juices.  

BUGS THAT SUCK: If you see groups of insects with orange bodies and long black legs clustered on tomatoes or vegetable plants, they are nymphs (immature stage) of leaf-footed bugs. When they grow up, they will be brown. They have sucking mouthparts and can damage tomato fruit, causing yellow spots on the ripe fruit. Vacuum them off with a hand-vac or spray plants with permethrin.

SLOW FOOD: Apply a slow-release fertilizer to your container plants outside to keep them well fertilized through the growing season. One application will fertilize for many months, saving you time and effort.

MURPHY'S TOMATO LAW: Birds will peck holes in tomatoes just before you decide they are ripe enough to harvest. If birds are a problem, cover your plants with bird netting or harvest the fruit in the pink stage and ripen them inside. Bird netting also works well to protect fruit crops, such as strawberries, blackberries, blueberries and figs, from bird damage and is available from nurseries or feed stores.

The human eye is powerfully attracted to bright colors. When you look at a yard, the first thing you will be the  colorful flowerbeds. Our eye…

Garden columnist Dan Gill answers readers' questions each week. To send a question, email Gill at gnogardening@agcenter.lsu.edu. 

For a summer full of colorful flowers and lush foliage, consider adding summer bulbs to your gardens. Most summer-flowering bulbs are native t…

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Dan Gill is a retired consumer horticulture specialist with the LSU AgCenter. He hosts the “Garden Show” on WWL-AM Saturdays at 9 a.m. Email gardening questions to gnogardening@agcenter.lsu.edu.

Garden columnist Dan Gill answers readers' questions each week. To send a question, email Gill at gnogardening@agcenter.lsu.edu. 

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