Tom MacCubbin:
Some tips to reuse container soil.
Question: In a Plant Doctor reply, you suggested removing the soil from previously planted containers before adding new flowers and vegetables. What should we do with the soil?
Answer: Old soil is very usable but not for another container garden. Often these soils contain rot organisms and maybe insects, too. The removed soil can be added to garden sites or used as a top dressing to fill voids in lawns. When mixed with other soils the good organisms neutralize the bad ones to allow normal growth. After removing old soil from containers, also scrub them down with soapy water to eliminate more pests and debris before replanting.
Q: My eggplants are full of blossoms but no fruits. What is the problem?
A: Temperatures have recently moderated enough for eggplants, tomatoes and peppers to start setting and by now you should be seeing fruits. When temperatures are in the 55- to 85-degree range, the fruits begin forming and remaining on the plants. Make sure you are not over-fertilizing, which encourages more growth than flowers and fruits. A fertilizer application once a month is normally adequate.
Q: I have an overgrown split-leaf philodendron. Can the plant be cut back and expected to keep growing new shoots?
A: Once the main shoot is removed your philodendron should send out several new ones. Leave at least a foot or so of stem to start the new growths. Depending on how far back the plant is pruned, a month or two may be needed to mature and open the new buds. If you wish, the top portions can be rooted. Many gardeners are successful sticking the stems in the ground or in a container of soil and keeping them moist to grow more philodendrons.
Q: I lost several trees and shrubs due to the recent hurricane that eliminated my privacy. Would a podocarpus hedge survive in a halfday sun?
A: Your partially shaded site should be a good home for a podocarpus hedge. The plants may grow a bit lanky but good pruning can keep them dense to ensure your privacy. Remove the tips of the plants after each foot of new growth to keep them full of foliage. Such frequent pruning may mean it takes a little longer to grow tall plants but it produces a better hedge.
Q: I planted cucumbers for fall but all I get are flowers without fruits. When will the plants start producing cucumbers?
A: Plants in the Cucurbitaceae, or gourd family, which includes cucumbers, melons, squash and pumpkins, can be slow to form their first fruits. Many of the selections open lots of male flowers first and eventually produce female flowers with a little fruit behind the blooms.
Producing fruits gets even more complicated as most crops in this family need bees or other insects to pollinate the blossoms in order for the fruits to continue growth. Perhaps the male flowers appear first to draw in lots of insects so not to waste plant energy on fruits that might not develop. You can help bring in the pollinators by growing the cucumbers in full sun and planting extra flowers to keep the beneficial insects in the area. Also, avoid using insecticides during flowering.
Q: My lawn care company wants to apply extra potassium to my lawn for fall. Is this a good treatment?
A: Not that long ago we weren’t sure what potassium did for plants but we knew turf, edible crops and ornamental used a lot of this nutrient. Today we know it toughens the plants, making them more resistant to diseases and adverse weather. This nutrient, which is the third in a fertilizer analysis, also helps increase winter hardiness.
Potassium readily leaches out of the soil and should be included with most fertilizer applications. If your lawn is receiving regular feedings that include this nutrient, extra may not be needed. Many companies like to give turf a fall potassium application just in case it has been used by the lawn or washed out of the soil before cooler weather arrives.
Q: I have lime left over from preparing the soil for a new lawn. Can I spread the lime over the healthy lawn, too?
A: Don’t apply lime without a soil test. Too much can be as bad as not enough. Lime adjusts the soil acidity upward to the neutral and alkaline levels. Some plants won’t like the alkaline soils and could react by producing yellow leaves and poor growth. Have the soil tested through your local garden center or University of Florida Extension Office. Follow their recommendations when applying lime to landscape plantings.