Gardening Tips for May

Kathy Berryhill
Creek County Master Gardener

Temperatures are warming up!  According to, our 2” soil temperatures are in the upper 60s.  The warm sun and recent rains will encourage rapid plant growth this month.  The OSU Fact sheet (HLA-6004) Garden Planting Guide, recommends many vegetables that can be planted once the soil temperature is above 60 degrees.  Starting vegetables from seed would push harvesting out by 60-90 days, so it is better to purchase most plants now. Depending on the amount of garden space that’s available, plant for your needs.  A couple of tomato plants will provide up to 180 tomatoes!  Pumpkins plants for carving produce around 5 pumpkins per plant.  The smaller varieties yield up to 20 pumpkins per plant.  Plan to plant according to your need (including sharing) to maximize resources.

Gladiolus bulbs can be planted now.

Spring flowering bulbs are mostly finished blooming and what’s left behind is the unsightly yellow foliage.  This foliage is important for next year’s blooms.  As the foliage dies, it nourishes the bulb. Allow this process to complete before cutting the foliage or digging the bulbs to divide.  

Azaleas can be fertilized and pruned after the blooming is completed and benefit from this treatment now.   Other flowering shrubs such as weigela and forsythia can also be pruned after blooming. 

The ground is warm enough to plant summer annuals.   Bulbs such as cannas, dahlias, elephant ear, caladiums and gladiolus can safely be planted now also.  Take care to read and follow the instructions for water and sun needs.  For example, caladiums planted in too much sun will wither.  Dahlias planted in wet soil will likely rot. 

Continue to monitor newly planted vegetables, flowers and plants for adequate water.  The higher temperatures and sunny days deplete the water from the soil quickly and new plants don’t have established root systems to search for water.  Best watering times are early morning and late evening, taking care not to splash water on the leaves. 

If you have space, include plants to attract pollinators.  Nectar-rich perennials such as coneflower, butterfly bush, dianthus, black-eyed susan, salvia and phlox will encourage colorful visitors to your yard.

Adapt a consistent fertilizing schedule for roses to encourage big, beautiful blooms.  While many may consider roses to be a “trouble plant”, it’s really more like a long-term relationship that requires a lot of care and attention.  Continually check roses for aphids and watch for the development of black spot disease.  If a systemic treatment hasn’t been used, several rose sprays are available to treat these problems.  Read instructions carefully before applying spray.  An alternative to the use of pesticides is to introduce ladybugs into the garden.  Ladybugs are one of the best-known garden predators available. Both the adult ladybug and the larvae feed on aphids, eating up to 50 per day.  Additionally, ladybugs feast on other soft-bodied pests such as mites and insect eggs. Ladybug suppliers are found online and can be shipped directly.