- Author: Help Desk Team
Bermuda buttercup (Oxalis pes-caprae) has become a tenacious and frustrating weed throughout California. From November through April, bright yellow flowers on leafless stalks and green shamrock-like leaves pop up in many of our landscapes. While it was brought from South Africa as an ornamental plant, it escaped cultivation on its route to being a chronic nuisance. It competes with other plants and is very difficult to control.
Bermuda buttercup develops from underground bulbs that produce a single vertical stem. A loose rosette of leaves will appear at soil level after the first rain. Small, whitish bulblets develop on the stem, and new bulbs form underground. Each plant can produce about a dozen small bulbs each year that easily detach from the plant and will increase the plant's spread quickly.
A couple of our favorite vertebrate pests (gophers and voles) consider oxalis bulbs to be a yummy food source and can spread the bulbs to new locations as they carry them back to their underground dens.
The best way to control Bermuda buttercup is to prevent its introduction into your garden. Don't move soil or plants from an infested site to another location that is free of the weed. Unfortunately, for many of us, it's too late for that tactic. So, what can we do when faced with the cheery yellow flowers popping up throughout the landscape?
Hand pulling can provide control if the entire plant is removed, including the underground rhizome and bulb. It's difficult to find all the bulbs without sifting the soil very carefully. Repeatedly removing the tops of the plants will eventually deplete the bulb's resources, but it can take years to be successful. It's important to remove the tops of the plants before they flower and form new bulbs.
It is difficult to smother Bermuda buttercup with thick mulch or even weed block cloth because it is a strong plant. If cardboard covered with a thick layer of mulch is used to try to smother the weed, continued vigilance in monitoring and pulling new growth will be needed in subsequent years. In one garden, weed cloth was laid under a brick walkway. The following winter, Bermuda buttercup pushed its way up through the weed cloth between the bricks. This made removing the plants even more difficult because the plants were being held in place by the weed cloth.
Several herbicides will effectively kill the tops of the plants, but will not kill the bulbs, so regrowth will occur.
Whatever method you choose to combat a Bermuda buttercup invasion, you will need to be persistent and prepared to continue in subsequent years.
For more information about managing Bermuda buttercup, see this web page: https://ipm.ucanr.edu/PMG/PESTNOTES/pn7444.html
Help Desk of the UC Master Gardeners of Contra Costa County (SEH)
- Author: Help Desk Team
Many of us have seed catalogs arriving in the mail this month, so now is the time to start thinking about your summer garden. We are publishing this article again because starting plants from seed is a great way to lower costs and increase the variety in your vegetable garden.
The seeds of many vegetable plants can be planted indoors several weeks before the usual outdoor planting date. In addition to the bonus of earlier harvest times, your young plants are protected at their most vulnerable stage from inclement weather and the hungry pests that love to feast on small, tender vegetable plants. Planting from seed also gives you access to a much wider variety of vegetables than you would get when purchasing seedlings from local nurseries or big box stores.
Most of us are not lucky enough to have a heated greenhouse or cold fame. Despite that, you can have success starting seeds indoors as long as you provide the conditions they need to germinate and grow. Here are some tips for successful indoor seed starting:
· Purchase your seeds from a trusted source. Fresher, higher quality seeds will have a higher germination rate (meaning more will sprout). Know your local climate zone and last frost dates and choose varieties that are appropriate for your area.
· Some vegetables do best when their seeds are planted directly into the garden. Peas, beans, and most root crops such as carrots, beets, and radishes are some of them. Check the information on the backs of seed packets and consult the CCC Vegetable Planting Guide below to find out which of the plants you wish to grow can be started early, and those that should be directly seeded in the garden.
· Time your seed planting. Not all vegetable plants grow at the same rate. From seeding to planting in the garden, tomato plants can take 5–8 weeks, while cucumbers or melons take 3–4 weeks. Plan your seed planting so that your plants are ready to go outside when the soil and air temperatures are sufficiently warmed up. A good rule of thumb is to wait to transplant outdoors when nighttime temperatures are consistently above 50°F. For more information on the timing of planting, check the backs of seed packets and the CCC vegetable planting guides provided below.
· Use a seed-starting mix. These mixes don't contain any actual soil, but they provide ideal conditions for sprouting seeds. Most importantly, they provide a good balance of drainage and water-holding capacity. Soilless mixes commonly contain some combination of these materials: peat moss, sphagnum moss, perlite, and vermiculite. Don't use garden soil as it doesn't drain well and may harbor plant diseases.
· Container choices. A wide variety of containers can be used- just make sure they are at least 2 inches deep. Recycled containers such as empty plastic yogurt or takeout containers work well. Make sure to poke holes in the bottom that will allow excess water to drain out. Used plastic plant pots, six-packs and flats are good choices and can be reused for many years but should be sanitized before reuse.
· Sanitize previously planted containers. Remove all soil and debris by scraping, brushing, and rinsing. Use a solution of 9 parts water and 1 part bleach to kill any possible plant pathogens. Soak plastic and other non-porous containers in a bucket of this solution for 10 minutes. Porous containers such as terra cotta should be soaked for 3 hours to overnight. Rinse thoroughly and allow to dry before using.
· Plant seeds at the proper depth. Check the seed packet for planting depth recommendations. You don't need to be too precise, just be sure not to plant any deeper than the directions suggest. The general rule is to plant the seed two to three times as deep as the seed is wide. For example, large seeds like beans should be sown about an inch deep, and very tiny seeds should be barely covered by the soil mix. Tamp down the soil very gently after planting and water right away to thoroughly moisten the soil (until excess water runs out of the drain holes). You will not always get 100% germination, so plant a few extra seeds.
· Don't forget to label all your containers. Do this before or while you are planting your seeds. Use materials that will stand up to wet conditions. Pencil on plastic or wooden stakes will work well.
· After sowing, set the containers in a warm location. Most vegetables germinate best at temperatures between 65° and 75°F. A warm location in your home is one option. Another is to invest in an electric heat mat. They are made specifically for starting seeds and growing indoors, are an excellent way to provide consistent warmth, and will last for many seasons. Find heat mats online or at local garden shops and nurseries.
· Keep the seed-starting mix moist, but not soggy. Plant roots need both air and water. Saturated soil can cause seeds to rot and seedlings to die. Also do not allow soil to dry out. Check daily and water as needed. Clear plastic dome covers or plastic bags (be sure to keep them from touching the soil surface) can be used to help keep the soil evenly moist. Remove the covers after germination to allow for air circulation and to help avoid fungal diseases.
· As soon as seedlings emerge, make sure they get bright light. Placing them next to a sunny window is an option, but containers will need to be turned occasionally to keep the plants growing straight. Better results can be obtained by providing additional light from 40-watt cool white fluorescent tubes. Suspend the lights about 4¬–6 inches over the tops of the plants and keep them on for 14–16 hours each day. Be sure to move the lights higher as the plants grow taller.
· When the seedlings have one or two sets of true leaves, it's time to thin and transplant. If planted in individual pots, you will want to remove all but one seedling per pot. Cut or pinch extra seedlings off at the soil line. If several seeds are planted in flats or small cell packs this is the time to transplant them into larger individual pots. Four inch or quart size containers will give seedlings enough room to grow until it is time to plant in the garden.
· Begin to fertilize weekly. Plants that remain in the seed starting mix will now need added nutrients. When your seedlings have one set of true leaves (see illustration below), use a half-strength fertilizer (liquid fertilizers are easier to use and apply). Organic mixed fertilizers are a good choice. Many of them will provide a range of nutrients that include micronutrients. You may decide to transplant your seedlings into a potting mix that already contains added nutrients, in this case adding fertilizers may not be necessary.
Illustration and photos courtesy of S. Hoyer
Climate zones and last frost dates:
More information on vegetable gardening can be found in the links below:
Help Desk of the UC Master Gardeners of Contra Costa County (SMH)
- Author: Help Desk Team
The answer is YES! And it is easy!
If you prune, your rose flower bushes will
• Be larger
• Have more flowers
• Will be more balanced and fuller
• And the health of your plant improved!
Most roses need to be pruned only once a year. All types of rose bushes benefit from pruning and if roses are not pruned regularly, they deteriorate in appearance and flowers will become smaller.
When to Prune?
Most roses should be pruned when they are dormant. In this area of California, roses are generally dormant between December and February and anytime in that time frame is fine.
The pruning objective is to work toward an open, airy, well-shaped and balanced V-shape cane structure.
What you will need
• A pair of sharp, clean pruning shears
• A pair of clean long-handled lopping shears
• Thick gauntlet gloves to protect your hands from the thorns
• A small hand saw for larger cuts
• Alcohol and a cloth for cleaning your tools
How to approach the task
These pruning practices pertain to all garden roses regardless of type:
• Use your loppers to cut off the top one third to one half of the plant to better see its structure.
• Clear the area underneath the plant from all leaf and other organic debris to expose the crown/canes and sucker origins.
• Make your pruning cuts with your shears at a 45 degree angle about 1⁄4” above an outward facing bud. The angle should slope away from the bud. A cut made at this point will heal rapidly and water will drain away from the bud.
• Remove all dead, broken or damaged canes down to the crown.
• Undesirable canes have discolored pith or hollow centers indicating disease, insect or weather damage.
• Remove any crossing canes keeping the best looking ones.
• Remove spindly canes (smaller in diameter than the size of a pencil).
• Remove any suckers. These are extra vigorous shoots arising from rootstock below the bud union.
• Suckers should be removed completely, not just clipped off where they emerge from the soil. This can be done by moving the soil away from the trunk until you can see where the sucker is connected to the trunk. Grab ahold of the sucker close to the trunk and pull downward to break it off.
• Choose 3–6 strong, healthy, outside canes per plant to keep and leave 3–5 buds on each cane.
• Remove EVERY leaf from the newly pruned bush as diseases and insects tend to over winter in old leaves.
• Consider applying an insecticidal soap or horticultural oil after pruning and while roses are dormant. Soaps and oils smother overwintering scales and insect eggs and are least harmful to beneficial insects. A good time to apply is when no rain or fog is expected within a day.
• Shape your rose bushes as they grow. Keep the branches balanced and the centers open for airflow.
General pruning techniques for various types of roses
Hybrid Tea, Grandiflora, and Floribundas Roses
• Cut back between one third and one half of the previous year's growth on all the canes you plan to keep (4 to 7 canes). The average pruning height for Floribundas and Hybrid Teas is between 12 and 18 inches, but taller growing Hybrids and most Grandifloras may be left at 2 feet. For most hybrids this means leaving between 5 to 10 buds per cane.
• Miniature roses are 6 to 12 inches high, with tiny blooms and foliage. Miniature roses do not need special pruning. Just cut out dead growth and remove the hips.
• Old-fashioned Rambler roses have clusters of flowers, each usually less than 2 inches across. They often produce canes 10 to 15 feet long in one season. Rambler roses produce best on one-year-old wood, so this year's choice blooms will come on last year's growth. Prune immediately after flowering. Remove some of the large old canes. Tie new canes to a support for the next year.
• Large-flowering climbing roses have flowers more than 2 inches across, borne on wood that is 2 or more years old. Canes are larger and sturdier than those of Ramblers. Many flower just once in June, but some, called ever-blooming climbers, flower more or less continuously. Often this group is pruned in the autumn, any time before cold weather sets in. First cut out dead and diseased canes. After this, remove 1 or 2 of the oldest canes each season to make room for the new canes. The laterals, or side shoots, are shortened 3 to 6 inches after flowering. If the plant is strong, keep 5 to 8 main canes, which should be tied to the trellis, fence, wall, or other support. If it is not strong, leave fewer canes.
Link for rose pruning video: https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=16947
See this UCIPM site for more information on rose care:
Help Desk of UC Master Gardener Program of Contra Costa County (PDS)
- Author: Help Desk Team
At the end of the gardening season, there is an instinct to uproot spent plants and clear the soil for a fresh start, whether it be for a cover crop, a winter vegetable crop, or next year's summer crops. There are some really great reasons why pulling out roots after cutting back the plants' top growth is not necessary and can even be detrimental.
The roots that remain after removing your vegetable plants in the fall or cover crop plants in the spring are slowly decomposed underground by worms, bacteria, fungi, and other beneficial soil organisms. These organisms perform a vital role in the soil. As leftover roots decompose, they release organic matter and nutrients into the soil.
Decomposing roots enhance soil structure, making it more porous and helping with aeration. They contribute to the soil's water retention capacity. Organic matter released during decomposition acts like a sponge, holding onto moisture. This creates a good environment for beneficial soil organisms like fungi, bacteria, and invertebrates.
The network of roots left in the soil helps prevent erosion. The root systems act as anchors, binding the soil together and reducing the risk of it being washed away during heavy rain. This is especially important on slopes to maintain the integrity of the topsoil.
And finally, leaving the roots saves gardeners time and energy!
What if you want to plant something in that bed with the roots still there? Seeds or seedlings can easily be planted through and around the remaining roots. Those decomposing roots will help feed the new plants.
Is there ever a reason to remove roots? Yes. Occasionally inspecting the roots of plants you're removing is a good idea to check for root knot nematodes or other root problems. These microscopic roundworms attack a wide variety of plants. They cause swellings (galls) on roots that interfere with the nutrient and water transport system. If you noticed some of your plants didn't look as healthy as they should, it would be valuable to take a look at the roots. For more information about root knot nematodes, see this link: https://ipm.ucanr.edu/PMG/PESTNOTES/pn7489.html
Help Desk of UC Master Gardener Program of Contra Costa County (SEH)
- Author: Help Desk Team
Lettuce may not be a garden crop that causes you to perk up and say, “Tell me more.” You may be thinking, “Boring, I'll pass.” Or you may be the gardener who says, “I never could get that crop to grow.” Whatever your current thinking about lettuce, I hope to get you excited about this humble crop. There are not many garden vegetables with more diversity than lettuce, with more than 100 varieties in a wide range of colors, textures, and shapes.
If you need more encouragement, lettuce is a great hydrator, being 95% water. Lettuce is a powerhouse when it comes to vitamins and minerals. Vitamins A and C play a strong role in supporting the immune system, eyesight, and reduce inflammation. Iron, folic acid, calcium and potassium also add to the health benefits of lettuce.
Lettuce (Lactuca sativa) has been cultivated for thousands of years. The name is derived from the milky liquid produced when a leaf is broken from the stem.
Cool Season vs. Warm Season
We tend to think of lettuce as a light summer food, but lettuce is a cool weather crop. The optimum growing conditions for lettuce occur in fall and early spring. Many cool season lettuce varieties have good tolerance for cold temperatures and do well in low-light conditions.
Summer lettuce is in high demand as a crop, causing breeders to develop lettuce varieties for summer growing conditions with good success. These lettuce varieties are bred specifically to be heat tolerant and are slow to bolt and less bitter as they mature.
Seed Germination & Transplants
Lettuce seeds will germinate in 3–10 days depending on conditions.
Seeds can germinate in soils as low as 40°F but germination will be slow. The optimum temperature for seed germination is 55°–65°F. Above 70°F lettuce seeds germinate poorly, resulting in undersized, misshapen, elongated heads. At higher temperatures lettuce seeds may completely fail to germinate.
Fall lettuce seeds need to be in the ground in late September so they can reach 75% maturity going into the low-light days and cool nights of our winter months.
Spring lettuce seeds should be started indoors in early February. This will give you a jump on planting out in the spring after all danger of frost is past. Continue to sow seeds at 2-week intervals for continuous production.
Lettuce seeds are very small and should be planted with a very light covering of soil (¼ inch). Be generous when sowing your seeds, as some will not germinate, and others may be lost to birds. As they mature, the thinnings can be added to salad or used in sandwiches. The final spacing for lettuce plants should be 9–12 inches.
Many gardeners start with lettuce transplants from a local nursery, followed by seed sowing at 2-week intervals. This gets you off to a quick start and keeps you in a continuous supply of lettuce. To keep your lettuce crop growing through the summer switch to a variety listed as heat tolerant or slow-to-bolt.
Lettuce does best in loose, well-drained soil with a generous addition of compost added before planting. A source of organic nitrogen can also be added to the soil before planting. Alfalfa meal, cottonseed meal, and fish or kelp meal are all good sources for slow, consistent nitrogen release.
Watering & Fertilizing
Keep the top 1–3 inches of the soil consistently moist as lettuce roots are shallow and dry out easily. You will want to provide adequate nitrogen for this fast-growing crop. Organic fertilizer is slower to become available. If you are using transplants, give them an application of liquid fertilizer 2 weeks after transplanting.
Frost Protection & Shade Cloth
Winter grown lettuce, though it can tolerate cool temperatures, will need protection from frost, while summer grown lettuce must have some shade protection.
Many lettuces can be harvested as baby greens. Some of the looseleaf varieties can be harvested in any stage of development by cutting the larger outside leaves and leaving the smaller inner leaves to mature. Mature lettuce does not get better, it gets bitter, so don't wait to harvest. To keep lettuce at peak freshness, harvest early in the morning. Wash the leaves thoroughly in cold water, then remove as much excess moisture as you can—a salad spinner is a great tool for this job. Store lettuce in the refrigerator in a plastic container with a lid with several damp paper towels added to create a humid environment. Garden fresh lettuce, stored in this manner, will last 7–14 days.
Disease & Pests
The most common diseases of lettuce are Botrytis rot, lettuce mosaic virus, and mildew. Keeping lettuce leaves dry is the best way to avoid disease from getting a foothold. Good air circulation and drip irrigation are two helpful practices.
Lettuce may fall prey to occasional pests including cutworms, leafminers, caterpillars, aphids, whitefly, snails/slugs and earwigs. Access the UC IPM website for information on controlling specific disease, insects, and vertebrate pests such as birds and deer.
Butterhead / Boston / Bibb: These lettuce varieties form a round, loose head. They range from delicate and buttery to bright and crisp. Leaves tend to be large, making them an excellent choice for wraps and sandwiches. *Days to maturity 45–55. These varieties can be harvested anytime during development.
Looseleaf: This lettuce grows from a central stalk but does not form a head. These varieties are easy to grow and perform well in shaded areas or in low light. They are tolerant of warm temperatures and are slow to bolt which make them a good choice for multi-season growing. *Days to maturity 45-55. These varieties can be harvested anytime during development.
Crisphead / Summercrisp / Batavian: These lettuce varieties are known for their crisp snap and sweet flavor. They form a round, compact head. Often the outer leaves are darker with tender light leaves in the interior. Crisphead is a true cool weather variety which will stand up to very cool temperatures but beware, it is quick to bolt when temperatures rise and it's a favorite of snails and slugs. This would be a good choice for starting indoors in January for transplanting in February after all danger of frost is past. *You will need to plan ahead as some of these varieties take 70-100 days to reach full maturity.
Cos / Romaine: This lettuce is very upright, forming a column. They can be tightly closed, semi-closed, or open heads. This lettuce has a crisp, creamy white heart with the outer leaves remaining sturdy and dark. It is unforgiving of poor growing conditions and is not well adapted to warm weather. There are interesting varieties in the seed catalogs with some beautiful deep burgundy varieties in the offering. *You will need to plan ahead as some of these varieties take 75-85 days to reach full maturity.
I hope I have piqued your interest in experimenting with both winter and summer lettuce in your garden. The varieties and variations are truly exciting, many of which you will never see in your supermarket or even at farmers markets. Whether you select your varieties by color, shape, texture, or even their fun names, I hope you have decided to give lettuce a place in your garden. May it be a delightful and successful experience!
Help Desk of UC Master Gardener Program of Contra Costa County (BHD)