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Plant winter squash in June, July to harvest in fall

Q: I planted acorn and butternut squash last winter from seed and they didn’t grow. Now they are growing. The acorn squash is doing really well. I thought winter squash would ripen in the winter. Will these be edible?

A: Winter vegetables are harvested during the cool fall, winter and early spring months but planted in mid to late summer. Summer vegetables are planted in the spring for a summer harvest. The name tells you when they are harvested, not when they are planted.

Winter squash require 80 to 100 days to mature before harvesting. The number of days depends on the variety of squash. If you want to harvest winter squash in the fall months of September, October or November then plant them in June or July but no later than August.

Planting in the summer gives them enough time to mature and harvested before freezing weather begins in December. To estimate when to harvest squash, count forward 90 days from the date the seedlings emerged from the soil.

To estimate when to plant squash, determine the harvest date and count backwards 90 days. If you plan to harvest in December, add the five extra days when counting backwards to accommodate the cool temperatures before harvest.

If the weather is cool at the time of harvest, you can leave them on the vine a week or two longer with no problems.

I have found the best way to judge if acorn squash is mature enough to harvest is its color. There is a spot on the side touching the ground that turns from light yellow to lemon yellow.

Butternut squash is more difficult to judge using color. For butternut, it is best to mark the day to harvest on your calendar. Experienced gardeners use pressure from their thumbnail on the skin to judge maturity.

Be sure to remove the squash from the vine leaving about 1 inch of the vine attached. This is the proper method for harvesting and helps preserve it longer after harvest.

Q: My squash plants are doing great this year, but last year they died and I had to remove them. What can I do to help keep them alive this year?

A: The biggest problem leading to vine death is squash bugs. They live and reproduce on the leaf undersides so they are not easily seen unless you turn the leaves over.

The first sign of squash bugs is leaf scorch and yellowing. Leaves on the squash vine turn yellow and the edges scorch when squash bugs are heavily feeding.

If leaf scorch and yellowing is a big problem, it may be too late to initiate squash bug control. You will most likely have to rip out the vines and harvest what you can.

Squash bug control has to start early before the damage starts. Turn the leaves over even if they look healthy. Look on the undersides of the leaves. Squash bugs live in large groups. If you see large colonies of these insects, remove them by hand or use a cordless vacuum cleaner.

If you must spray, spray chemicals on the leaf undersides using soap and water every couple of days. If soap and water doesn’t work try pyrethrum sprays.

Some people claim planting after June 1 helps avoid squash bugs. Others say it makes the difference.

Q: I continue to have problems with my dwarf naval orange tree purchased in 2012. These problems include bite marks on the leaves, brown and or black spots that look like coffee grounds, yellow leaves, shriveled leaves and tiny bugs.

A: The bite marks and brown and or black spots may be related. Grasshoppers and other chewing insects occasionally feed on citrus leaves leaving behind excrement that looks like coffee grounds.

Some insects’ bite marks are not a big problem. That may have been grasshopper damage from the past year. Unless you see a lot of it, just ignore it.

Winter cold damage causes yellowing or bronzing of citrus leaves. This type of yellowing is commonly seen in early spring and persists into the summer months on older leaves.

Yellowing of the leaves on new growth is nutritional. Liquid sprays applied to the leaves that contain iron usually help. These sprays should be applied three or four times a week apart to be effective.

The most common insects found on citrus are aphids on the undersides of leaves. They are usually clustered together by ants that care for them. You will see larger, mature aphids and the smaller immature ones living together. Insecticidal soap or sprays of soap and water applied directly on them usually take care of the aphids as well as the ants, but these sprays must be done frequently.

Q: I read somewhere that insecticidal soap should not be applied after bloom.

A: There is nothing wrong with using insecticidal soap after bloom but don’t use it while the plants are in bloom because of hurting the bees. Insecticidal soap, as well as soap and water sprays, will kill bees. In fact, they kill any insect that gets in the way of a spray, good or bad.

If you make your own insecticidal soap, use a high-quality soap such as a Castile type. Don’t use liquid detergents made for dish washing. Nearly all these contain chemicals that can damage plants.

Spray the undersides of the leaves and spray weekly when temperatures are warm but not hot. On days where temperatures are extreme, spray in the early morning hours or the evening when it’s cool.

Q: I bought a gardenia plant from Costco a month or so ago. It looks robust with green, shiny leaves. It gets sunlight in the morning and shade in the afternoon. Before the buds bloom they wilt and fall off.

A: The usual reason for gardenia flower buds to drop off of the plant before opening is a lack of water. Gardenias can be very finicky. Finding the perfect spot and perfect combination of water and fertilizer is a challenge when growing gardenias.

Make sure your gardenia is in a pot that has holes in the bottom made for drainage. Apply enough water so that it drains out of the holes in the bottom of the container. This is very important for flushing salts out of the soil and wetting the soil in the entire container.

Do not water daily. How often to water depends on the size of the container and the size of the plant. Purchase a houseplant soil moisture meter for less than $10 from any nursery or garden center and use it to judge when to water.

Stick the tip of this meter into the soil about 4 inches in several locations. Water the soil thoroughly and read the soil moisture meter right after watering. Read it at several locations in the pot.

The meter should read “Wet.” Do not water again until the meter has moved to the midpoint on the scale halfway between wet and dry.

Q: Last year my catalpa tree developed brown spots and yellow leaves. The nursery told me it was fungus and I needed to spray the tree, which I did. This spring everything started nicely, but in the past two weeks the brown spots were back and worse than ever.

A: Catalpa is not the best choice for our dry desert climate and harsh soils. A tree commonly planted here that is a cross between catalpa and desert willow is called chitalpa. However, it more closely resembles desert willow than catalpa, lacking the larger, “elephant ear” leaves.

I suspect the problem with your catalpa is not disease but rather a cultural and management problem. Even though it is a very tough tree and can tolerate lots of different soil types and environments, it can struggle here in our desert.

If this tree has been doing well in the past, then I suspect it’s an irrigation problem and needs more water. Its robust size and large leaf size puts this tree into a high water use category.

Bob Morris is a horticulture expert living in Las Vegas and professor emeritus for the University of Nevada. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.

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