When it comes to buying plants for your garden, quality matters.

That doesn't mean looking for the biggest flowering plants with the most blooms. You might also want to pass over those tomato plants with very early tomatoes clinging to the vine. Instead, look for small, young plants. They're less likely to be root bound and will quickly catch up to their greenhouse-matured counterparts.When shopping for tomatoes and similar plants, the Penn State Extension Office and most agriculture centers advise gardeners to look for short, "stocky" plants, perhaps 4 inches tall and up to 4 inches wide. Stems should be about as thick as a pencil. (More leggy plants should be avoided, but if they are your only option can be planted more deeply, with some of the "leggy" main stem buried in the soil.)Eileen East, a master gardener with the Carbon County Penn State Extension Office, also encourages gardeners to do their homework before buying flowers.Look for the best plants that match your garden's water and sunlight conditions - and try to remain knowledgeable about any diseases that are impacting our local area."Impatiens are still on the 'do not buy' list because the downy mildew that killed them all a couple of years ago is still present," she said.Downy mildew causes slight yellowing and curling of the leaves in its early stages, along with a white or grayish-white growth on the undersides of leaves.It eventually leads to leaf drop and the plant's death. Downy mildew cannot be treated once a plant is infected, and mildew spores can remain dormant in the ground over winter."If you want impatiens, choose imported varieties or get plants from a local grower who can guarantee them disease-free," says East."Even then, the blight spores will be in the air if your neighbors have infected plants."East also stays away from boxwood and pachysandra, which are both being affected by boxwood blight. Boxwood blight is caused by a fungus and can lead to spotted leaves, complete leaf loss and blight of the plant.Fungi spores can also survive for years in the soil.