Garden Docs demystify the difference between a shrub and a perennial

Ted writes: This is the first year that I am trying to grow pumpkins. Evidently the growing conditions (extreme heat) are perfect because the vigorous vines are crowding out the other vegetables. I thought I had provided plenty of growing space. Can I prune back some of the vines to keep them under control but still have pumpkins?

Answer: Yes. King's Nursery recommends a light tip pruning or simply taking the long trailing vines and wrapping them in a circular fashion around the developing pumpkin. It seems you may, at this time, be seeing some blossoms, so let that guide you as to where to prune.

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Wally asks: I am searching for a perfect lavender that can withstand difficult soil conditions. Can you offer any ideas?

Answer: There is a fairly new Sunset introduction, Lavender x allardii ‘Meerlo.' Sunset describes it as drought-tolerant, with unusual variegated and fragrant foliage with a bonus of year-round appeal. ‘Meerlo' will tolerate difficult soil conditions. I have not tried this particular lavender in my own garden but it should be interesting to give it a try. As always, check around our local nurseries for availability.

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Doug asks: Lately I have seen a shrub with vibrant bright yellow flowers that seem to display their color all summer. Do you know the name of this shrub?

Answer: I am fairly certain that you are referring to Hypericum, commonly known as St. Johns wort. Hypericum frandosum ‘Sunburst' is an evergreen shrub that reaches 3 feet high by 4 feet wide, is deer resistant, and is evergreen in our planting zone. It has a mounding growth habit. There are other varieties such as H. hidcote that flower all summer too. It is a real show stopper when combined with a few yellow foliaged conifers like Cedrus deadora ‘Gold Cone.' But avoid creeping St. Johns wort, which is prone to rust problems.

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Rick writes: Your previous column referred to the shrub plantings along Fountaingrove Parkway. It has been brought to my attention that the misuse of Roundup herbicide in the center strip has damaged many of the shrubs with sections of their foliage killed. The chemical was probably sprayed when it was windy. This is a reminder to never spray on windy days because the spray drift will invariably kill nearby trees, shrubs, and perennials.

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Nancy asks: What is the difference between a shrub and a perennial?

Answer: A shrub (a noun) is a woody plant smaller than a tree, and usually having multiple woody stems branching from or near the ground.

Perennials (an adjective) can be woody plants or herbaceous. Herbaceous perennials are nonwoody that die back to the ground in late fall. The roots survive in the winter and re-sprout in the spring. Perennials are plants that live more than two years. More confusing are perennial plants such as rosemary, clematis or lavender that can grow into small woody shrubs in our relatively mild Sonoma County weather. The same plants will die back in colder regions, thus their identification as perennials.

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Growing tip: Set transplant pepper starts 14 to 16 inches apart. Floating row covers will protect the plants from insect damage. Peppers need a constant supply of moisture of 1 inch a week as the fruits develop. Mulch with organic matter to help retain moisture and eliminate weeds fighting for moisture.

Dana Lozano and Gwen Kilchherr are garden consultants. Send your gardening questions to pdgardendoctor@gmail.com. The Garden Doctors can answer questions only through their column, which appears twice a month in the newspaper and online at pressdemocrat.com.