If it’s spring, millions know one thing for sure: It’s time for spring allergies. Runny noses, sniffles, watery eyes, headaches and congestion are the result of allergens found in pollens or molds.

Experts recommend a number of ways to lessen exposure to pollens and to avoid allergic reactions.

The first key is to minimize outdoor activity, especially between 5 a.m. and 10 a.m. and on hot, dry, windy days when airborne pollen counts are at their highest.

Keep windows closed at night and when riding in a car. When in the car use the air-conditioner’s “recycle” mode to keep pollen out. Indoors, use a dehumidifier to keep the air clean.

Garden as smartly as possible by eliminating such pollen-producers as ragweed, sagebrush, redroot and pigweed. A single ragweed can produce a million grains of pollens a day. When mowing your yard, wear a dust mask.

Paul James, master gardener and host of Home & Garden TV’s “Gardening by the Yard,” has a few rules of thumb for allergy-free gardening.

“Small flowers with little color tend to cause more allergies than large brightly colored flowers,” he says. “And, strangely, off-white and greenish-colored flowers cause more allergies than all the others combined.

“Trumpet-shaped flowers seldom cause allergies because their pollen is held deep within the flower,” he says. “Fragrant plants as a rule don’t produce as many pollen allergies, but they may cause allergic reactions in people who are hypersensitive to certain odors.

“And believe it or not, there are people who risk going into shock when exposed to the smell of certain flowers, such as roses or gardenias,” he warns.

“You should stay out of the garden on windy days when pollen is blowing all over the place,” James advises. “You should avoid planting pollen-producing plants near areas where you spend a lot of time, such as the patio or near windows you like to open on nice days.

“And if you’re allergic to grass pollen, you should cut the grass and weeds before they have a chance to flower.”

When it comes to mold allergies, don’t over-water indoor plants, as soggy soil is a home for mold. Remove dead and decaying leaves, compost and wood piles from near your home: They’re mold magnets.

James agrees that compost piles are a source of mold, but adds that a compost pile is almost a necessity in a good garden. “So, if you’re allergic to mold, have someone else turn your pile and spread your compost for you.”