Gardening Tips for May 2025

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Summer Annuals - Petunias, Lobelia, Zinnias Profusion Series, Salpiglossis sinuata, Celosia.

Perennials- Leonotis leonurus, Lobelia cardinalis (likes water but worth it), Centaurea, Veronica, Mimulus, Nemesia.  

Shrubs - Roses, Lantanas (many are frost sensitive-used as annuals), Rhododendron,

Abutilon. 

Vines - Clematis hybrids (may re-bloom when deadheaded), Mandevilla and Thunbergia alata (frost sensitive-used as annual).

Veggies – Summer Squash (Zucchini, Patty Pan, Crockneck etc.), Basil, Beans, Corn, Tomatoes and so many others. 

Extras - Insecticidal Soap Concentrate, Stakes, Gardening Velcro Tape, Jute Gardening Tie, Maxsea Fertilizers.

 Tips for Growing Vegetables

• Slugs in Strawberries: In 3 Blog posts, see How Mary Managed this Pest.
• Watering - We ask a lot of our plants. Here in our Mediterranean climate (Santa Rosa CA) we don't get the summer rains other areas do. In Sonoma County we have approximately a six month period for possible rainy days followed by approximately a six month period of drought. With this in mind, now is the time of year it’s super important to flush irrigation lines and check all emitters so that your plants will be happy throughout our hot/dry summer. Lawns- A lawn needs water when you walk on it and the blades do not spring back up. Water in short burst rotation-ex: 5 minutes water, rest fifteen minutes, 5 minutes water, repeat a three times. This allows time for the water to soak in and prevents run off. Increase time as weather heats up. Roses-most roses (especially hybrid tea roses) do best with regular watering.  
• Container plants - Apply at least a one inch layer of compost as mulch to container plants. Use water holding polymers at planting time and/or add to long lived plants in containers. The polymers will help keep the soil moist and allow a few days in between waterings instead of watering everyday, in most cases. Avoid putting the polymers in the bottom of the planting hole as this can push the plant up when the polymers get plump from holding water.
• Basil – Plant by seed or six pack plants starting now. Plant more in 2 to 3 weeks for successive planting. If there is room, plant Basil groups in different places in the veg garden instead of all in one place. This helps with pest management and also Basil can grow well in one spot and not as well in another. The most important task when growing Basil is to pinch out the tip growth as the plant grows up so that it branches low and the plant becomes full of leaves from the bottom up and not just a tall, spindly plant. Pinch all the tips out 2 to 3 different times, let it grow in and anytime it looks like pinching is needed here or there do it again. Do not allow Basil to flower because this can change the taste of the leaves and the plant will start making seed.
• Pruning - After the flowers fade from spring flowering shrubs, you can prune Lilac (prune off all dead flowers just under the base of flower), Rhododendron, Azalea, Camellia, and Flowering Almond -There are different types of pruning depending upon what your intention is for your plants. When you would like to improve your confidence for pruning contact Mary for an appointment. Ferns - if you have not pruned out the old fronds from your ferns do it now. Follow all the dead fronds down to the base of the stem and cut out entire frond at the base; being careful not to cut the new growth or accidentally break new fronds off.  
• Pest Management - When you see ants crawling up and down your fruit trees, ornamental shrubs and other plants this is a sign that your plants may be infested with aphid or other piercing/sucking insects. First, control the ant population. Best to use bait (usually a liquid) instead of sprays. Also, wash off the aphids with a strong stream of water. If the infestation is still heavy step up to insecticidal soap (remember the follow up spray-follow directions on the bottle). Sometimes, if you control the ants, the beneficial insects will show up to control those aphids for you. Red Spider Mites are Mites not Spiders and they are hard to manage. If you have lots of tiny webbing in a plant this, more than likely, is a sign of Spider Mites. Neem oil may not be enough to manage the population and you'll need to use a stronger product. Sometimes just blowing the webbing apart with water or wiping it off will help disrupt the mites but may not do much to lower the population. Mites like hot, dry, and dusty environments. Washing off shrubs a few times a month helps too.
• Fruit trees - Although there is a natural thinning of fruit in nature referred to as “June drop”, it’s still a good idea to thin fruits on most fruit trees a little before June drop. After June drop you can thin some more. The most important reason for thinning fruit is to lessen the weight on the branch so that you do not come out to your garden one morning and see an entire branch on the ground and a big gaping wound in your fruit tree. Another reason to thin is to encourage bigger and more healthy fruit! Plus, thinning fruit helps fruit trees have more consistent fruiting instead of lots of fruit one year and hardly any the next. Thinning also can help manage pests by taking away tight spaces where they like to hide.
• Weeds - For more about how to manage weeds Watch The Gardening Tutor video: Weeds, How They Grow and How to Manage Them.  
• Fertilizing - After the flowers fade from Camellia, Rhododendron, and Azalea, fertilize with an acid fertilizer so they get a good start on the year it takes for them to form next year’s flowers! Gardenias appreciate regular fertilizing to keep flowering throughout the growing season. Use an acid fertilizer once a month for in ground plants and every two weeks (at half strength) for container plants. Blueberries will appreciate some acid fertilizer this month too! Blueberries are great for large containers. Mulch blueberries with redwood compost and they will love it! Watch The Gardening Tutor video: Two Quick Methods to Apply Fertilizer.  
• Nasturtiums - Now is the time to plant your seeds or seedlings of Tropaeolum (Nasturtium). Remember, once you have established your plants you can start to hold back on the water. Watering Tropaeolums less creates more flowers. Watering more creates bigger leaves and fewer flowers.  
• Sunflowers - Seeds can be sown every few weeks now for a succession of blooms all summer. Last seeding can be end of August for Sunflowers at Halloween.

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ALL CONTENT by Mary Frost (no AI).