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LifestyleColumnistsJessica Damiano

Garden Q&A: Help with marigolds, hydrangeas, mulch

Pink hydrangeas on display for sale for the

Pink hydrangeas on display for sale for the upcoming Easter Holiday at Martin Viette Nurseries on Apr. 15, 2014 in East Norwich. Credit: Heather Walsh

DEAR JESSICA: I live on Long Island and have seeds from last year’s marigolds. When is the right time to plant them outside?

Jackie Jager, Freeport

DEAR JACKIE: Marigolds germinate and grow quickly, making them ideal for sowing directly into the garden. In early May, after the danger of frost has passed, select a site that receives full sun for all or most of the day, and sow seeds about an inch apart. They will sprout within a few days, and most varieties will bloom in roughly eight weeks. For earlier blooms, start seeds indoors now and move plants outdoors in May.

DEAR JESSICA: I have several Macrophylla hydrangeas and did not remove dead flowers last fall. I know not to prune now, but when should I remove dead blooms? When should I fertilize plants, and what kind of fertilizer should I use?

Denise Gentile, Bellport

DEAR DENISE: You can remove spent blooms at any time, as it won’t affect future flowering. Just pinch or snip off only the dead flower, not the entire stem.

You can fertilize either by applying compost or composted manure to the soil around plants (but not touching plants) once a year in spring, or by using a 10-30-10 slow-release fertilizer once or twice a season, but never after August.

Avoid products that list the highest number in the N-P-K ratio (nitrogen-phosphorus-potassium) first, as that represents nitrogen, and too much nitrogen will force plants to direct energy away from blossoming and toward green growth, which will result in large, flowerless plants. Although all three components are vital for plant health, it’s the phosphorus that promotes blooming and fruiting. Potassium supports a healthy root system and the overall health of the plant.

DEAR JESSICA: Can you explain why you advise so strongly against applying mulch until May?

Sue Kropp, Dix Hills

DEAR SUE: The purpose of mulch is to keep the soil moist and its temperature even, suppress weeds and keep things looking nice and tidy. It also helps keep soil from eroding and reduces soil compaction around delicate roots. If applied too early in the season, it will be counterproductive, trapping the early spring coolness in the soil instead of later-season warmth, which will inhibit root and plant growth.

DEAR JESSICA: In the fall, I purchased Scotts’ Nature Scapes Deep Forest Brown Best Mulch with Color Guard to put down on our holly tree. What is your opinion of this type of mulch?

Marilyn McCarthy, Oakdale

DEAR MARILYN: I am not a fan of treated or dyed mulches, for aesthetic reasons as well as for plant and soil health. But getting beyond my personal taste, the dyes used in colored mulches concern me.

Some mulches are purportedly dyed with vegetable-derived color, but a complete listing of ingredients isn’t supplied on packages so there’s no way of knowing exactly what else is in the product. It may be true that vegetable dyes are used, but that is not a guarantee that chemicals aren’t also present.

The source of the wood in many colored mulches concerns me, as well, although Scotts’ Nature Scapes does not appear to be problematic in that respect. Its package label states the company “never uses recycled waste wood, which may contain nails or harmful chemicals. Only natural forest products are used.” The same should not automatically be assumed of other brands or of bulk mulches.

Fertilizers, pesticides, herbicides and even mulches will over time leach components into the soil that may be taken in by plant roots. Some may adversely affect ornamental plants — or get into the food you’re growing. And almost all will end up in the groundwater and potentially in your drinking glass.

DEAR JESSICA: I have some well-aged horse manure that resembles topsoil. Can seeds such as tomato, cucumber and bulbs for elephant ears be planted into the manure without adding soil? If so, what kind of results can I expect?

Tom Tierney, Greenlawn

DEAR TOM: I once experimented by growing a tomato plant in straight-up compost, and the plant grew well and produced a beautiful crop. I’m not sure you’d get the same results from pure manure. Although it’s rich in nitrogen and some minerals, manure could be lacking in other nutrients. It also could contain salt levels in excess of those tolerated by many plants. Too, manure doesn’t have the same structure as soil — or even compost — so roots may not anchor as well as they should.

If you choose to experiment, I’d be interested to learn of your results, so please let me know and I’ll pass along your findings to readers here.

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