Ciscoe Morris, Seattle Times garden writer, offers tips on transplanting young trees, dealing with Brussels sprouts that did not form sprouts and getting rid of brown blotches on the leaves of a lilac tree.

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Q: We’re moving. Two years ago I planted several baby trees around my yard including a serpentine birch, a pine tree, a Japanese maple and a dogwood. Is it possible to transplant them to our new home?

A: It should be easy to transplant all of the trees you mentioned, especially since they’ve only been in the ground for two years. Wait until the trees are dormant and have dropped their leaves.

The rule of thumb is to dig 10 inches diameter of rootball for every inch of diameter of trunk at ground level. For example, if the trunk is 2 inches wide at the base, dig a 20-inch-wide rootball. You can tie the rootballs up with burlap to transport them, or if the rootballs aren’t too big, simply pot them up in black nursery pots and replant them in their new home as soon as possible.

Since the trees are so young, the rootballs will be fairly easy to handle, but make sure you consider how big these trees will get before you decide where to replant them. If they grow too large for where you plant them or if you place them too close to the house, it’ll be a major undertaking to dig them up and move them 10 years from now.

Q: I planted three Brussels sprouts this spring and they turned into beautiful 26-inch-high plants but no sprouts. How come?

A: How depressing! A number of factors can prevent sprouts from forming. The first consideration is variety. Brussels sprouts that take a long time to mature sometimes don’t form sprouts until it’s too late in the season for them to size up well. Varieties that ripen early, such as ‘Franklin,’ usually form nice, large sprouts in time to fatten up before frost occurs.

Avoid using fertilizer that is high in nitrogen. That encourages foliage at the expense of sprout formation. The best fertilizer for Brussels sprouts is organic tomato food. Work in a half-cup under each start when you plant them.

Perhaps the worst thing you can do is wait too long to plant starts, allowing them to get rootbound and stressed in their pots. Stressed plants usually bolt and rarely produce sprouts.

Finally, even if you do everything right, unseasonable temperatures (too hot or cold) may prevent sprouts from forming.

Plant your starts in mid-May and make sure the soil stays evenly moist, especially in hot weather. Then all you can do is hope for a mild spring and summer. My last piece of advice is to let the nice, big formed sprouts get hit by a freeze or two to make them sweet.

Q: What disease is causing ugly brown blotches on the leaves of my lilac tree?

A: The blotches look like they’re caused by a disease, but the brown, dead-looking spots on the leaves of your lilac are actually being caused by an insect. The lilac leaf miner is a small, brown moth that lays eggs between the epidermal layers of the leaves. Soon after, a little green caterpillar hatches and causes the blotches by feeding between the leaves.

Although the damage isn’t harmful to the lilac, the brown blotches are quite unsightly.

Fortunately, a product is available that will control this problem if it is applied in a timely manner. BioNEEM (available online) is an organic, environmentally friendly spray that repels leaf miners and prevents the moths from laying eggs in the leaves. Apply this product by spraying it on the leaves in early May and again in early July and you shouldn’t see any of the ugly blotches for the rest of the season.

Ciscoe Morris:; “Gardening with Ciscoe” airs at 10 a.m. Saturdays on KING 5.