Gardening : What Shade Tree Won't Hurt the Lawn?


QUESTION: I would love to have a beautiful shade tree in my yard, and I like Liquidambars, but I worry that too much shade would kill my lawn. Can you recommend any shade trees that will not hurt the lawn?

ANSWER: It is difficult to maintain a decent lawn under many kinds of shade trees. Liquidambars don't work well, partially because of the shade, but mostly because of their invasive surface roots; also their stickery seed-balls become a nuisance in the winter. It's too bad.

I personally like pecan trees ('Stuart' and 'Western Schley' do best here), even though they tend to grow quite large; but they are elegant and stately--and they produce those wonderful nuts! Sunset recommends them as lawn trees in our area, as well as the following:

Albizia (Silk Tree)--airy, umbrella-shaped tree with puffy pink flowers; Cinnamomum (Camphor Tree)--stately evergreen tree with light green leaves; Ginkgo ' Autumn Gold ' (Maidenhair Tree)--unusual foliage, gold autumn color; Gleditsia 'Sunburst ' (Golden Honeylocust)--airy tree, gold-tinted foliage; Koelreuteria (Goldenrain Tree)--yellow spring flowers become clusters of papery 'Chinese lanterns' in the fall; Liriodendron (Tulip Tree)--large tree with distinctive lyre-shaped leaves; Plantanus acerifolia (London Plane Tree)--a superior sycamore, but like the Liquidambar it also drops ball-like seek clusters in winter.

I'm sure there are other appropriate trees, but these may be the best and the most readily obtainable. Most will grow 20 to 30 feet tall in about 10 years, and some will eventually grow much taller. Mature specimens may be seen at the L.A. State and County Arboretum in Arcadia.

Best Way to Prune Red Raspberries

Q: Concerning the pruning of red raspberries I am getting conflicting advice. Some say to cut the bushes down to 14-16 inches in early January, while others say to only remove the old canes, which have borne fruit in the summer. Which is correct?

A: Both answers are more or less correct! The distinction lies in whether you have "single-crop" or "everbearing" raspberries. Ortho's book "All About Growing Fruits & Berries" gives clear and concise instructions.

"Single-crop" raspberries produce their fruit in late spring and early summer on side shoots that sprout from years-old canes. When the harvest is over, remove these old canes completely, and train up the new canes for next year's crop.

"Everbearing" types produce spring-summer fruit on laterals that form along last year's canes, and fall fruit on canes that develop this spring and summer. For these, cut off the canes that fruited this spring. Train up the new canes, which will fruit at the top in the fall. Then remove this upper portion after harvest, leaving the main length of the cane for fruiting next spring.

Pumpkins May Need Help in Pollinating

Q: Imagine my surprise and delight when a volunteer pumpkin patch sprang up on a sunny, but neglected, patch of "lawn" where we carved our jack-o-lanterns last Halloween! The three or four vines rapidly ate up eight square feet of lawn, and now display huge leaves and blossoms. I drip-water the vines once or twice a week. Problem: the pumpkins reach about two inches in size, turn yellow and brown at the flower end, and fall off. What do I do now?

A: Pumpkins are related to squashes, gourds, melons, even cucumbers, and can be grown similarly with relative ease and success. These plants require hot weather in order to do well, and they truly thrive when planted in garden soils rich in steer manure.

Your plants may simply have been waiting for the weather to warm up (which it certainly has done now) or they may need assistance with pollination. As you look at the flowers on your pumpkins (or squashes, etc.), you will note that some are on plain stems, while others develop at the tip of a baby pumpkin (or baby squash, etc.). Those on the plain stems are actually male, or pollen-bearing, flowers; and those at the end of baby pumpkins (etc.) are female, or pollen-receiving, flowers. Normally bees or flies transfer pollen from the male flowers to the females, but sometimes they need help. You can facilitate this process by removing a freshly opened male flower in the morning and dabbing the yellow dust from the central pollen structure onto the structure in the middle of a freshly opened female flower. It's simple to do and almost always results in the formation of a fruit at that flower. Have fun!

What Vine Won't Damage Roof Tile?

Q: I'd like to have a vine on the roof of my detached garage. What water-thrifty and evergreen vine would not damage the tiles? I've heard that Lady Bank's Rose would be good. I have seen lots of bougainvillea on roofs, but my neighbor told me hers has damaged the gutter.

A: Bougainvillea is probably the best selection for your purposes, but it does require substantial support. Lady Bank's Rose, especially the yellow form, is very pretty, but it loses its leaves and is barren in winter; and it only blooms once in early spring. Other good vines to consider are Honeysuckle, English Ivy and Violet Trumpet Vine (Clytostoma or Bignonia).

How Often Should Roses Be Pruned?

Q: I just returned from Santa Maria, Calif., and friends there had pruned their roses heavily after the May blooming period. They contend that roses should be pruned twice a year. Should they? I do mine once a year.

A: I guess if it works for your friends, they can do it. But for most gardeners the once-a-year major pruning is quite sufficient.

Many dedicated rose enthusiasts let their roses bloom and grow until hot weather hits in July, then cut back the plants to one-half or two-thirds of the height they attained, without removing too many leaves. This helps to control plant size and shape, and usually makes the fall blooming periods somewhat more spectacular; but it isn't necessary to get pretty roses.

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