We have an apple and a pear tree that were planted in our yard before we purchased our home. We have lived here five years, and every year, I sample the fruit at different times to see when it might be ripe or close to ripe. Fruit from both trees tastes terrible, no matter when we taste it. Our horses will eat it, but no human could stomach it.

We tried spraying for worms and fertilizing, but no luck. There is also a plum tree in same area that does fine: lots of fruit and very tasty.

Should I just cut them down and start over, or is there a solution to this problem?

– Christine Mantz, Auburn

According to UC Master Gardener Bill Pierce, a couple of factors could be the cause of poor-tasting fruit.

Most fruit trees are propagated by grafting a variety with desirable fruit properties onto the rootstock of another variety known for hardiness and disease resistance. The former owners may have lost or pruned away the grafted parts of these trees and allowed the rootstocks to grow. Varieties used for rootstocks usually do not have tasty fruit.

Or they might have planted seeds from fruit they had eaten. Seedlings from hybrid trees rarely produce great-tasting fruit.

Excess irrigation sometimes causes fruit to be tasteless; however, since the plum in this area is producing acceptable fruit, this is probably not the problem.

Instead of starting over, you might consider grafting these trees to known varieties. Since the rootstock is already there, grafts in these trees will grow faster and produce fruit sooner than if you were to plant new trees.

Select varieties that are suitable for your climate. Grafting is usually done in early March.

For sources of scion wood – the fruiting wood that will be grafted onto the rootstock – and for experienced grafting people in your area, check with Eisley's Nursery, 380 Nevada St., Auburn; or at your local Cooperative Extension Office, 11477 E Ave., Auburn; (530) 889-7385.

If this is something you'd like to tackle yourself, there will be a demonstration of T-bud grafting at the Fair Oaks Horticulture Center in Fair Oaks at 8:30 a.m. June 18. You can also ask questions about grafting and fruit trees at the next Master Gardeners' Open Garden Day at the horticulture center, 11 a.m. to 2 p.m. April 13. Both events are free. The horticulture center is in Fair Oaks Park at 11549 Fair Oaks Blvd.

For information on the various events held at the center by the UC Master Gardeners, go to http://cesacramento.ucdavis.edu. A copy of the workshop schedule is available at that site.

We put our coffee grounds in our compost, but can there be too much? Our cantaloupes last summer tasted like coffee.

– Dennis Lau, Carmichael

Coffee grounds are an excellent source of organic matter for the soil when used in moderation, said UC Master Gardener Bill Pierce.

But yes, you can overdo it with coffee grounds. Their pH is in the acid range. Most plants thrive in slightly acid soil; 6.5 on the scale is best. (The lower the number, the more acid the pH.)

Cantaloupes require a pH range of 6 to 7.5. Excessive applications of coffee grounds might have lowered the pH into the 5 range.

When using coffee grounds as a mulch, try to distribute them over a wide range to avoid concentrations. Inexpensive pH test kits are available at nurseries.

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