Q: I've noticed that a lot of tree trimming is going on at the moment. We have a large coast live oak that could do with a bit of care. Is now the right time to do that?
A: Live oaks should be pruned in the summer when their growth slows. Winter or spring pruning can cause them to produce "witch's brooms", wispy growth at the branch ends that are the result of a fungal infection. When you do prune, all the cuts should be made back to where the branch starts, as stubs may not heal and are likely to die back and cause rot problems.
Q: I planted some of our native yarrow (Achillea millifolium) several years ago. It has done well and slowly spread, but lately the center seems to be dying, although the outer bits seem just fine. What is wrong?
A: Actually, it's pretty certain that nothing is wrong, fortunately. Plants, like people, have a limited number of days on earth--since the plants in the center are the oldest parts they are most likely just reaching the end of their life. All you need to do is cut the stems down to about 6" tall and dig up the clump. Then remove the dead center and toss it in the compost, divide the healthy outer portions and replant them to start new clumps. Now is the perfect time to do this.
Q: I know we don't get enough natural outside chill for hyacinths, tulips or Dutch crocuses, but I'd like to plant some anyway. What do I need to do?
A: You are right that these need a cold period in order to bloom so put them in brown paper bags (not plastic) in a part of the refrigerator where they will be cold (but not frozen) for 6-8 weeks. Be aware that too much ethylene gas, which is given off by ripening apples (and bananas and pineapple), can cause the bulbs to rot or sprout prematurely, so keep these fruit in airtight bags. You can also sometimes buy prechilled bulbs and just plant them directly. Also, unlike the classic Dutch tulips, some natural species tulips do fine without a chill, and so do saffron crocus which bloom later (and you get to harvest the saffron!). You might also consider opting for some of the Tazetta narcissus varieties which tolerate our climate quite well--I have some paperwhites that have bloomed dependably for the last 20 years.
Q: I'd like to replace some of my Bermuda grass lawn with raised beds. How can I get rid of the grass?
A: Each bit of the Bermuda stolons or rhizomes left in the soil, as well as any seeds, can grow and once you irrigate your beds, they are very likely to do so and come up in the vegetables. Digging up all the area and sifting the soil is labor-intensive (I've done this so I know!) and you are still likely to miss some pieces. I personally avoid herbicides so you might consider solarization of the areas where the beds will go and for at least 2 feet around the perimeters of the beds to kill as much as possible of the Bermuda. Now is a good time as we will have hot weather for the next few weeks and solarizing takes 4-6 weeks. Remove the grass or mow it short (put the refuse in the trash). Water the area as that makes the heat penetrate better, and then right away put down a layer of clear UV resistant polyethylene over the area--1.5-4 mils plastic drop cloths are an option--weighing down the edges. There are likely to be bits of Bermuda lower in the soil that don't get killed, but most of the seed and the bits in the top few inches should be. After the solarization, be sure not to cultivate the soil or you may bring up bits and seeds that didn't get killed. The other alternative is just to resign yourself to continually removing the Bermuda as soon as it appears in your beds. If you are vigilant, eventually you should defeat it but it is likely to take quite a while (no method is instant). Landscape fabric covered with mulch around the beds will help control invasion from the edges.
Q: Now that we've been spending so much time indoors, I've increased my collection of houseplants which is great for my mental health. However, some have developed unsightly brown tips and edges to the leaves. How can I prevent this?
A: There are a lot of reasons this might happen: overwatering, underwatering, low humidity, drafts, too much fertilizer, high salt concentration in your tap water or a combination of some of these. First of all, find out what the preferred growing conditions for the plant are so you can narrow down the possible culprit(s). Then change one of the factors and see if the plant improves. If not, try the next possibility. Sometimes it's a hard slog to figure this out.
Q: I've been pruning the exuberant new growth on some of my shrubs to keep them in bounds and noticed that some of the new growth on my variegated ones is completely green. What should I do?
A: As soon as you see these, prune them out down to the place where they start. Green shoots are more vigorous than the ones with the variegated leaves--the plant will favor them and eventually you will have an all-green plant if you ignore them.
Q: I'd like to save seeds from my poppies to plant next year. What is the best way to do that?
A: Once the seed pods start to turn brown, you can cut them off and put them in a dry area in the house or garage on some paper to dry out completely. After a couple of weeks, you should hear the seeds rattling around when you shake the pods. At this point, you can cut off the top of the pod and shake the seeds out. Remove any bits of the pod and store the seeds in an airtight container out of the light. Another way to collect them is to use cheesecloth or old nylon stockings to form a bag around the pods and let the seeds mature on the plant and let the pods split open naturally. This is a bit more work but ensures that the seeds are ripe. When the pods open, cut them off and shake out the seeds. Let them dry out for a couple of weeks and then store them airtight in the dark.
Q: What are the odd-looking grubs I've been finding?
A: These are beetle larvae. The photo that was sent showed fat little critters about an inch long with golden brown heads, dark gray hind ends, curled on their sides like a letter “C”. Although there are several different types of beetles whose larvae live in the soil, most of the grubs look similar and most eat roots. However, this is not a problem if there are only a few of them. if you find some in your pots or beds, you can just toss them out in some open space for birds to eat. I usually leave most of them alone since many are larvae of the beautiful, iridescent green fruit beetles that buzz around in summer, and I like those. The damage to my plants seems to be very small. No treatment is needed in a lawn if there are 5 or fewer per square foot (dig up a couple of square foot patches to check and then replant the sod). If there are more than 10, then the grass may be in trouble and you may see brown spots appearing in summer. Grubs don’t do well in dry soil, so water your lawn the minimum to see if that takes care of the problem. You might be able to add parasitic nematodes (a type of tiny worm) to the soil. Ask at your local garden center and be sure they are alive when you buy them. If these don’t do the trick, as a last resort, you can try applying a chemical in July or August next year. If you do use one, water it in to encourage the grubs to move up to the wet area. However, the number of grubs varies a lot from year to year, so postpone using chemicals until you are sure you have a persistent problem.
Q: What are some annuals or perennials that will seed themselves around my garden?
A: One of my favorites is Honesty (Lunaria annua) whose clusters of purple flowers are followed by fascinating seed pods. Where you have this one year, you will have more the next! Because it does so well in my shady garden, I collect the seeds and sow them around every fall. I also love the groups of small white daisies that feverfew (Tanacetum parthenium) produces from spring to fall. In a sunnier area, nasturtiums (Tropaeolum hybrids) make a colorful (and edible) carpet. And of course, the tiny white flowers of sweet alyssum (Lobularia maritima) spread with enthusiasm and attract lots of pollinators. In sunnier and drier spots, patches of our native fiddleneck (Amsinckia menziesii) wiil increase each year, producing hairy leaves and coiled stems of tiny yellow-orange blossoms.
Q: My tangerine produces a lot of flowers but hardly any fruit. What might be the problem?
A: Citrus tends to produce a lot of blossoms and a lot of these get fertilized and start to set fruit, which then drops. This can be due to a number of cultural problems. First, citrus are heavy feeders and do best if fertilized monthly, or twice a year if you use slow-release fertilizers. Second, keeping the area from about a foot from the trunk out to a few feet beyond the drip line evenly moist helps. Too much or too little water can be a problem: every week or so in hot weather, and every three or four weeks in wet weather. Third, excessive pruning can shock the tree. All that being said, about 80% of the fruit that starts out is likely to drop under the best of circumstances, but that usually still leaves a good-sized crop.
Q: How can I tell if my avocados are ready to pick?
A: Unlike a lot of fruits, avocados won't ripen on the tree. When you think the crop is about ready, pick a couple of avocados every few days and see if they ripen at room temperature in a week or two. When some do, you can assume most of the ones on the tree are ready to pick. If picked too soon, the fruit won't ripen and will be rubbery; if left too long, the oils start to taste rancid and the flesh will be dry. Left on the kitchen counter, avocados will be ready to use when they give slightly when you press them. If you have too many ripe ones, you can toss them in the freezer and use them later for guacamole.
Q: An animal broke several stems of my cane begonias a while ago, so I trimmed them and put them in water. Now they've developed roots and I'd like to plant them back in the garden. Is there anything special I should or should not do?
A: Roots that develop in water are somewhat different than ones that develop in soil, so you need to reduce the shock from going from total wetness to much dryer surroundings. Pot the cuttings up very gently and water them well. Cover with a plastic bag for a week or so to reduce water loss. Keep the soil consistently moist for a few weeks thereafter so that normal roots can form. Then move the pots outside in a sheltered location for a week or so and reduce watering a bit. Finally, move them into larger pots or into a garden bed that has similar conditions to the ones where the parent plants thrived.
Q: Recently I've seen a lot of spider webs spanning my garden paths and patio, and even across my driveway. Should I worry?
A: If the occupant is mottled brownish, with a body about 1/2" long, and sits in the middle with its legs drawn up (less of a target for its predators) it is most likely a common orb weaver (Neoscana oxacensis). These spiders will rush to the edge of the web if you disturb it to get away from you. They could bite if you provoke them and don't let them retreat, but they are not dangerous like black widows. Most eat the web each day and spin a new one so the webs usually are pretty debris-free. These, like all spiders, help to keep down the number of insect pests and, since common orb weavers are only present in the garden fom late summer to fall, I usually leave them alone if at all possible and just walk around them.
Q: I'd like to combine ornamental and edible plants in my garden beds. Do you have any suggestions?
A: Almost all food plants do best with quite a lot of sun, but many will tolerate some shade if you are OK with a smaller crop. Plant some genetic dwarf or semi-dwarf fruit trees and keep them pruned to about 8 ft tall so they are easy to harvest, and plant under and around them. Check out our April, 2019 newsletter for suggestions about vegetables that will do OK with some shade. For those that need full sun, like tomatoes and beans, you can grow them on structures like teepees or trellises in the midst of a sunny bed. Rainbow chard, red sorrel, variegated sages and thymes, artichokes, fennel, nasturtiams and many other plants are both good to eat and decorative. The key is too make sure that the plants in any particular area have similar light, watering, and fertilizer requirements.
Q: I have some very large pots and filling them with potting soil is going to be expensive and make them really heavy. What can I do?
A: You can fill up to a third of the space with something lightweight and then cover that with landscape cloth to prevent soil from moving down. You can use an upturned plastic pot, crushed aluminum cans, non-degradeable packing peanuts, broken styrofoam, or other similar items as long as they are clean and won't decay, so no wood or paper products. Be sure the drainage hole in the pot isn't blocked. After you put in the lightweight stuff and the landscape fabric, add the soil, water it in, and let that drain before adding your plants. Potting soils tend to sink somewhat because watering reduces the air spaces in the soil. If you plant first and then water, your plant may end up lower in the pot than you want.
Q: I have roses of one color growing in a mixed bed and just noticed some long, flexible canes with different colored flowers growing several feet away. What has happened?
A: Most roses are grafted onto a rootstock because this is an easy and efficient way to produce a lot of a particular variety for sale quickly. If branches sprout from the rootstock, the blooms that the suckers produce will be different from the top, grafted portion. Suckers arising from below the graft are easy to see and remove, but sometimes a root will send up a new shoot several feet away from the original shrub. You can dig down and remove this new plant and the root it is growing from
Q: What is a safe way to get rid of those healthy looking grubs I'm finding all over my garden?
A: Sounds like beetle grubs. Our September 2013 newsletter had a short article on them. A lot of these are larvae of those big, beautiful, iridescent green fruit beetles that buzz around later in the summer. I like them so I usually leave them alone. However, I replanted a very large pot last year and there were dozens so I just tossed them on the ground for the birds to find.
Q: My daffodil and narcissus flowers are long gone and the leaves are covering up the perennials and annuals around them. When can I cut them down?
A: Next year's blooms depend on bulbs or corms storing enough energy this year, and that is done through photosynthesis in the leaves. The best method is to leave them until they start to turn yellow and then cut them off. If they are really a problem, then you could tie them together loosely so they don't fall over. Some people fold them over and tie them in a bunch but the less light the leaves get, the less efficient they will be. This is true for other bulbs and corms such as chasmanthe, montbretia, gladioli, sparaxis, bluebells and so on. All do best if you let them die down naturally.
Q: My Mexican sage is looking very scraggly. How can I make it look better?
A: The old stems of Salvia leucantha can lose a lot of their beauty at the end of the year but it's easy to rejuvenate a plant. You'll notice a lot of new growth arising from the ground now and as soon as this is at least 6" tall, you can cut the old stems down to ground level. In a couple of months the plant will look healthy and bushy and soon it will be busy attracting butterflies and hummingbirds.
Q: A plant about a foot tall with clover-like leaves and yellow, conical flowers that close at night just appeared in my garden. Is it something I'd want to keep?
A: This is Oxalis pes-caprae (Bermuda buttercup, sour grass), a South African native that has naturalized in California. Some people love it, and others do not. It goes completely dormant in early summer and re-emerges in winter. It produces large quantities of small bulbs making it hard to get rid of completely once established. It can be pretty invasive so if it appears where it might smother other small plants as it spreads, dig it out as soon as you see it. If it volunteers in an area where that is not a problem, you might decide to leave it.
Q: Can I plant the poinsettias I bought outside?
A: Yes, but these Mexican natives tend to grow into largish, weak-stemmed shrubs and the new "flowers" are likely to be smaller than they were on the plant when you bought it. If you live here in Southern California and want to give it a try, keep the plant in bright light, out of drafts, and water it well when the top half inch of the soil dries out. In early March, cut all the stems down to about six inches and move the pot outside to a shady area for a couple of weeks. Then plant the poinsettia in a sunny, frost-free location and pinch out the stems occasionally to keep it shorter and fuller. Note: Some people are allergic to the milky sap these plants produce when injured, so it's a good idea to wear gloves when working with them.
Q: What's a good way to keep track of where my perennials are once they die down, and places where I've sown seeds?
A: One no-cost and easy way is to save a short, sturdy piece of stem and stick it in the ground to identify the spot. Another simple method is to use the cheap wooden skewers you can buy in packets of 100 at most markets. (If any of our members have additional suggestions, please send them along so we can share them!)
Q: What are some shrubs I could plant now that will provide berries for birds?
A: Mahonias have yellow flowers in late winter or early spring, followed by blue berries. Species range from groundcovers to 10 ft tall. Most like shade and average water, but desert mahonia, M. fremontii, takes sun and low water. Mahonia "Soft Caress" has soft leaves instead of the usual prickly ones. Red-flowering currant, Ribes sanguineum, takes part shade, and its pink spring flowers attract butterflies and hummingbirds. Bearberry, Arctostaphylos uva-ursi, is a tough, spring-flowering groundcover that will provide tasty (to birds) berries in the fall, as will other, taller, manzanitas.
Q: I have a garden bed that repels water. What can I do?
A: First check to see if the surface has become compacted which often happens if it is walked on or if large water drops hit the surface regularly, and sometimes just as the bed ages. In this case, just dig down with something like a hand fork and gently loosen the top few inches. Try not to mix up the soil as that can mess up the habitat for beneficial microorganisms. If the soil dried out at some point so much that it is repelling water molecules, you can try loosening the soil a bit and then wetting the surface gently just to the point of runoff, waiting a few hours, and repeating this several times. If there are a lot of small, dry, broken down leaves or stems covering the ground, they may be repelling the water before it reaches the soil so try removing them from an area and see if that helps. Over time, the fungi that normally break down thick layers of wood mulch can clog the air pockets so you might alternate types of mulch. Compost or other soil amendments can help to add material that attacts water too, and of course you can dig out the bed and replace the soil. Commercial soil surfactants or detergent solutions can have adverse effects so should only be used if nothing else works and then cautiously.
Q: How dangerous are Africanized bees? What should you do if attacked?
A: Colonies of Africanized bees are still quite uncommon, thankfully, but if one is around, it can be a problem, and some deaths have occurred. These honeybees look just like regular ones and generally will leave you alone. However, it takes less to make them feel threatened, and when they do, large numbers of them will chase the object of their ire for long distances. You should always act calmly around your bees but if a swarm does start to attack, the best defense is to cover your head and face and get inside away from them immediately. If you are not near a shelter that can be closed off, run in a straight line until you find one or the bees give up.
Q: Can I prune my Cleveland sage back now to encourage it to rebloom and keep it from smothering nearby plants?
A: The consensus is that these sages, such as the variety "Allen Chickering", bloom only once and that pruning should be carried out in the fall and winter. At that time, you can shorten stems by up to 1/2 to keep the plant from getting leggy. However, since new growth won't sprout from old wood, you should be sure not to cut back to leafless portions. A little careful pruning now just to reduce its encroachment on its neighbors shouldn't hurt the plant.
Q: I have noticed a number of volunteer trees sprouting in my garden. How can I tell what they are, and what is the best way to get rid of them if I don't want them?
A: Three of the most common volunteers have large featherlike leaves composed of a midrib with a number of leaflets: Shamel ash has 5-9 leaflets, European ash has 7-11 leaflets, and Tree of Heaven has 11 to 41 leaflets (and the leaves have an unpleasant odor when crushed). A fourth common volunteer is the golden rain tree which has even larger leaves that have branches off the midrib with leaflets growing along them so it has a "ferny" look. If you don't want the tree, just water the ground to make it easier to dig and remove the plant with as many of the roots as you can. Or just keep cutting it off at the base every week or so and eventually it will give up.
Q: Is it better to buy or make nectar for hummingbird feeders?
A: Chris Verma, owner of Wild Birds Unlimited in Claremont, says you should not buy liquid feeds because they have additives that can harm the birds. To make your own, bring one part ordinary sugar and four parts water just to a boil and then let cool. Do not add any dye. If you want to have something red on a plain feeder, tying a ribbon on it will do. Be sure to replace the nectar and clean the feeder every few days to avoid stuff growing in it that would harm the birds.
Q: There are brown areas on my camellia flowers. What is causing them? Could it be too much shade?
A: Camellias like shade and don't like being transplanted so I think you'd be fine leaving the plant where it is. Camellias are subject to "petal blight" fungus which is almost certainly what you are seeing. This is very difficult to control and anti-fungal sprays are of limited effect. The best method is to remove affected flowers and be sure to clean up all the ones that drop, including every single petal. These should all be tossed in the trash and sent to the dump. With luck, the problem will recede in a year or so, but it requires vigilance. The Camellia Society has more info at https://www.americancamellias.com/care-culture-resources/insects-and-diseases/camellia-petal-bligh
Q: I love tomatoes but have trouble digesting the seeds. Are there any seedless tomatoes?
A: Although our March speaker on tomatoes, Dave Freed, hasn't grown these, he did mention that seeds of a seedless hybrid can be ordered from the Totally Tomatoes website, and we found that plants and seeds are also available from Burpees.
Q: I have some very shady and dry areas in my garden. Are there any plants I could grow there?
A: Definitely one of the hardest areas to find plants for, but cast-iron plant (Aspidistra elatior) and butcher's broom (Ruscus asculeatus) do just fine in quite a lot of shade and have low water needs. Slow growers and insignificant flowers but require very little care other than removing dead leaves occasionally.
Q: My chives still have some green leaves but they have flopped over. What should I do?
A: Give the plants a crew cut by cutting off all the leaves, both dried and green, to about an inch long. New leaves will start sprouting in a few days.
Q: Can you grow strawberries as house plants?
A: Our November speaker, Julie Bawden Davis, says "Yes, indeed" and suggests trying "Seascape" or "Albion" in a sunny window. Fertilize the plants regularly and keep the soil moist.
Q: At the October meeting on composting, a member asked if you can use ashes in your compost.
A: Speaker Dave Schroeder has written to say that you can use small amounts of fire place or BBQ ashes in the soil or in the compost pile as long as you mix them in thoroughly, but that ashes shouldn't be added to a worm bin.
Q: A friend just divided his clump of Chasmanthe and gave me some of the corms. How should I treat them?
A: Chasmanthe floribunda, African flag, is a member of the iris family. Plant corms about 3" deep in groups in light shade in well-drained soil. Plants are dormant in summer. Leaves appear in late fall, growing 3-4 ft tall, and the arching sprays of orange and yellow, thin, tubular flowers appear in early spring. A favorite of hummingbirds. More detailed growing information can be found at https://www.pacifichorticulture.org/
Q: Do you really need to wash and sanitize containers to reuse them?
A: The counsel of perfection is “yes” so that you don’t pass along any infectious material they may contain. [But I admit I usually just wash them out with water (unless the previous plant was ill) and have never had a problem.]
Q: Can you reuse potting soil?
A: Again, ideally no, you should spread it around and dig it into the ground somewhere (unless the plants were ill). However, I’ve left the soil in some very large patio pots for several years, just changing out the plants and adding fertilizer, and the plants have done well.
Q: Is there a way to kill grasshoppers without harming beneficial insects?
A: This is very difficult, as pesticides kill them all. The good news is that serious grasshopper invasions generally only occur every 8-10 years (although they can last 2 or 3 years). The following may help, but since grasshoppers are very mobile, they can migrate into your garden from other places outside of it.- Grasshoppers lay eggs in the soil, so tilling the surface 1-2 inches a few times in late summer, fall and winter may reduce the number that develop.
- The young hoppers like to live in areas of dense plant growth where spiders, blister beetles robber flies, and suchlike prey on the eggs and nymphs, so arrange to have a few areas like that.
- Grasshoppers prefer uncultivated, weedy, grassy areas, so if you have an out of the way spot, you might let it go (but keep it healthy) and hope the pests think of it as prime real estate compared to your weeded beds.
- Some birds eat young grasshoppers, so provide some perches in the garden. (Coyotes eat grasshoppers too, but you may not want to attract them!)
- Among vegetables, they generally give tomatoes, squash and peas a miss, but delight in lettuce, carrots, and beans and onions. Putting row covers over your vegetables can reduce the damage. Hungry hoppers can eat through fabric and plastic, so consider using metal window screening. Be aware, though, that covers` may reduce insect pollination of your crops, so you may need to do some hand-pollination.
Q: Poinsettias — plant outside or toss?
A: Poinsettias (Euphorbia pulcherrima) are frost tender, prefer acid soil, grow to 8 ft in the ground, and do not bloom well unless they get two months of total darkness at night in the fall. Darkness is hard to provide in an urban garden, so unless you enjoy a challenge, toss. If you do grow them, wear gloves when pruning as the milky sap of euphorbias can cause skin irritation. (By the way, poinsettias are not poisonous–that’s an urban legend.)
Q: Last year’s seed packets — use or toss?
A: Seeds don’t stay alive forever, but neither do they all expire immediately at years’ end. Like people, the ones in a packet vary a bit in life expectancy. If you keep your packets in a cool, dark, dry location, you can expect to get good germination for several years. Here are some approximate times (years in parentheses): corn (2), lettuce (6), beans (3), cucumber (5), eggplant (4), kale (4), melons (5), onion (1), peas (3), spinach (3), tomato (4), radish (5). If you have older packets and are worried about poor germination, plant more thickly than normal and remove any extras.