When do you trim a flowering crab tree? Does it bloom every year?

Flowering crabapples are the dominant spring-flowering trees in the northern states. Belonging to the genus Malus, apples and crabapples are deciduous trees with fruits ranging from the size of a pea to apples 2 to 4 inches in diameter. Those with fruits less than 2 inches in diameter are considered crabapples. They are generally small to medium, dense, rounded trees reaching a height of 15 to 25 feet. A few of the varieties have leaves that change color in the fall so they are considered trees with multiple season interest. Most, if not all, new hybrid crabs bloom annually, but older trees may or may not bloom every year.

The best time to prune your trees is in late winter or early spring before the leaves appear as it is much easier to see which branches should be removed and also gives the trees the entire spring and summer to form new growth. However, they can be pruned anytime, and if you want to preserve the total flower show for spring, do it immediately after blooming is complete this spring.

Consider the following reasons to prune before you begin:

1. 1. Prune dead, broken and diseased branches.
2. 2. Correct structural defects. Never allow two equally vigorous leaders to develop on exactly opposite sides of the same trunk. This will be a “weak” crotch, susceptible to splitting as the tree grows older.
3. 3. Cut suckers from the bases of the grafted plant. It takes a little more time, but digging out the suckers is even better. Crabapples are grafted or budded on another kind of root stock. Usually this graft or bud is never more than a foot or so from the ground. All suckers developing below this point should be removed as they will spoil the symmetry and sap the strength of the variety wanted. Left alone, they develop into an entirely different and unwanted plant.

Also remember to:

1. 1. Use clean, sharp tools.
2. 2. Disinfect the blades of your tools after each cut on diseased crabs, or you risk spreading deadly fire blight disease. Isopropyl alcohol works well.
3. 3. When pruning a branch or limb, the key is not too close and not too far from the limb or bud. If pruning a mature branch, be sure to leave the branch collar – the slightly wider part close to the trunk – completely untouched.

As I watered my houseplants this winter, I noticed a powdery white build-up on the sides of both plastic and terra cotta pots. Is this salt? I rarely use fertilizer, and when I do it is something organic, like fish emulsion. I thought salts come from synthetic fertilizers.

Synthetic fertilizers are seldom the only culprits. The best type of water for houseplants is rainwater or melted snow. Distilled water can be used, but the cost may be prohibitive over time as well as the work to carry the jugs into the house. Tap water (well or city) is generally suitable for nearly all houseplants. However, the water should stand overnight in a container to allow the chlorine to evaporate and to reach room temperature.

Whether you live in an area with hard or soft water, both can be harmful to your plants as they contribute to a build-up of excessive salts in the soil. Hard water contains calcium, magnesium and iron salts. Softened water is worse because the softening process exchanges calcium for salts that have no use. Plants use these salts in very small quantities. In large amounts they become toxic. What the plant does not absorb from the watered soil will appear as the white crusty deposits. Repotting in new potting medium will help the already affected plant, and leaching the soil (watering to the point of runoff each time you water, or at least monthly) will help prevent future salt build-ups.