“Hi — I just transplanted tomato starts from the bathtub to larger containers and used Black Gold All Purpose for much of it. I had one bag of All Purpose and one of Natural, Organic. I noticed that the All Purpose has more fertilizer in it. The Natural Organic has less, but it is natural and organic. Still, I’m thinking I should generally use the All Purpose — because it seems like the transplanted tomatoes have really benefited from the fertilizer in it (more than they might benefit from what’s in the Natural/Organic). What’s your perspective? I don’t think it’s my imagination that the tomato starts to look quite a bit better after transplanting into the All Purpose. I’m just not sure if they’ll do roughly equally well in the Natural and Organic Potting Soil. There’s less fertilizer. I don’t see the differences clearly yet with my starts for reasons that I won’t bore you with. Please advise. :-)” Question from Steve of Bow, Washington
Answer: The Black Gold All Purpose Potting Mix contains supplemental fertilizer to feed plants for up to six months, while Black Gold Natural & Organic Potting Soil contains no added fertilizer. That’s why you saw better growth in the seedlings planted in the All Purpose, but both are good choices for potted vegetable growing. I would also add that tomatoes are very heavy feeders, so I recommend adding fertilizer that is specially formulated for tomatoes anyway. There are loads of fertilizer options for tomatoes on the market.
We have several other soils that are ideal for tomato growing because they hold extra water and are OMRI Listed for organic gardening. These are Black Gold® Natural & Organic Flower and Vegetable Soil, which is very porous and fertile, and Black Gold Natural & Organic Ultra Coir, which holds extra water for thirsty tomatoes. From there, I recommend that you watch the video below with great tips for how to successfully grow tomatoes in containers.
When it comes to a good potting mix for succulents, fast drainage is essential. A good succulent mix must drain very well but also have some organic matter. Black Gold Cactus Mix has the perfect balance of good drainage and organic matter. When choosing a pot, pick one that is several inches larger than the last and has drainage holes at the bottom as well as a saucer to catch water.
Once your succulents are newly planted, it is smart to top the soil with decorative gravel to keep the surface dry and attractive. Pebbles and gravel for terrariums come in different sizes, textures, and colors. Those in light shades let plants stand out without overstatement.
“Why do some potting soils turn green? What is it, and how can I avoid this from happening? Thank you.” Question from Angela of Taylor, Michigan
Answer: Any potting soil can turn green. That is because it is algae, or more rarely moss, that is causing the green color, and excess water on the soil surface is the culprit. A green layer on your soil means too much water. When you water to the point where the surface soil is kept wet, this invites the growth of algae. Algae and algal spores can exist in soil, water, or even air, so “clean” soil won’t keep the problem away. The best way to avoid algae is to clean up and change your watering practices.
Cleaning Up Algae in the Pot
Start by skimming off the first couple of inches of greenish potting mix on your pot tops, and refresh with new potting mix. We recommend replenishing with Black Gold All Purpose Potting Mix. It is also important that you have pots that drain well and bottom saucers for watering. If you need to upgrade your plant’s pots, it’s worth it. Pots like these will enable bottom watering.
Watering to Avoid Algae
Allow the top two inches of potting soil to become dry between watering. This will halt algal growth. Another method is to water your plants from the bottom saucer only when they need it.
“If you plant flowers in a flowerpot, do you ever have to change out the soil, or does the soil never lose its nutrients? Question from Jessica of Phoenix City, Alabama
Answer: Potting soil must be changed or replenished every couple of years or so for many reasons beyond the fact that a plant may have outgrown its pot. Not only do plants remove fertilizer nutrients in the soil, but the soil components also break down and become more acidic over time. You can always add fresh fertilizer to the potting mix, but the changes caused by decomposition can only be fixed by adding fresh potting soil. Here are four important characteristics of fresh soil that are lost with age.
The Four Important Characteristics of Fresh Potting Soil
Lots of air pockets to facilitate good drainage and aeration for healthy root growth. (As potting soil ages, and its organic matter breaks down, these air pockets are lost.)
Better water-holding characteristics. (As potting soil ages, water is less available to plant roots.)
A more neutral pH. (As potting soil ages, it becomes more acidic, which many plants do not like.)
A better ability to distribute nutrients to plants. (As potting soil ages, plant roots have a harder time accessing fertilizer in the soil.)
After two to three years, replenish your pots with fresh potting soil. When I add new potting soil to my containers, I take the old mix and add it to my garden beds as an amendment. That way, nothing is wasted.
“In an effort to keep down the insect population of my indoor veggie garden, I’ve been sterilizing my soil in the oven or microwave. I’ve had whitefly and fungus gnat infestations from using Miracle Gro and other soils right out of the bag, so someone told me to sterilize, and it seems to work. However, if there are beneficial microorganisms in your Black Gold soil, I fear that sterilization may kill them. So, my question is this… should I heat sterilize my Black Gold organic soil before using it indoors? Or is that defeating the purpose of the soil’s ingredients?”Question from Holt of Georgia
Answer: Theoretically, fresh, straight-out-of-the-bag potting mix should be pest and disease-free. Black Gold® gets good grades in this arena, but if a bag gets slashed or torn during transport or is improperly stored, the contents can pay the price. (Only buy Black Gold® bags that are undamaged with contents that are not waterlogged.) Otherwise, you shouldn’t have to worry. Still, if you prefer to play it safe, soil sterilization is certainly helpful with preventing damping-off (click here to learn more), and it would kill any harboring pest eggs, but beneficial microbes will also pay the price.
The chief potting soil beneficials to consider are mycorrhizae and the good microbes in earthworm castings and sometimes compost. Other soil components, like Canadian Sphagnum peat moss and bark, are not particularly rich in any worthy beneficial microbes accessible to plant roots. Currently, we do not add mycorrhizae to any of our Black Gold® soils (unlike some of our Sunshine® mixes), but we do add earthworm castings and compost to quite a few, including our Black Gold® Natural & Organic Potting Mix. Sterilization would certainly kill any soil good guys, but if you are determined to sterilize, it should not impact your growing dramatically. And, you can always beef up your soil after sterilization by adding Black Gold® Earthworm Castings Blend from a well-sealed bag, or dry mycorrhizae spores, which are available at most garden stores.
Even after the sterilization of greenhouse pots, surfaces, and soil, pests may come. Every open door, window crack, or new plant brought indoors is a threat. When it doubt, fight back early using smart IPM. We have lots of blogs on the topic. (Click here to read an article about managing the worst indoor plant pests, and watch our video below about beating fungus gnats.)
In-ground, grasses are perfect for planting in dry stream beds and among wildflowers. (Photo by Maureen Gilmer)
When landscape grasses take on full autumn color in the western states, they are always the focal point of the late season. It is the driest part of the year when their life cycle peaks after flowers pollinate, seeds form and are finally released into the wind to repopulate the land. These annual reproductive structures are why ornamental grasses own the fall garden when few other plants bloom. Even in the early winter, the standing flower stalks offer attractive interest through the snow.
It’s the less desirable grass habits that are less understood. These influence selection, placement, and other issues you won’t hear about elsewhere. Here are some tips to help you select and design grasses into your landscaping, so they don’t become problems later on.
Grass Litter
When this Pennisetum sheds flower parts and seeds, it goes right into the pool. (Photo by Maureen Gilmer)
After pollination, grasses shed their flower parts. When the seed is released, they shed their hulls. A lot of fine litter is dispersed over a long period. If the grasses are located upwind from a swimming pool or water feature, the litter is blown directly into the water. This can make it challenging to keep pumps and equipment clear and the water quality sparkling.
Therefore, know the direction of your prevailing winds and storm winds before you decide where to plant grasses. Limit planting areas downwind or away from the pool. However, it’s common for wind direction to change with the seasons, so if you plant them poolside, planting them downwind is not foolproof. Cutting the seedheads back may be necessary.
Invasive Grasses
Native deer grass (Muhlenbergia rigens) is quite long-lived and fairly trouble-free.
The reason you hear so much bad press about fountain grass (Pennisetum species and varieties) is that they love our climate and sprout anywhere there is enough moisture to grow. There are many ornamental species with weedy tendencies. Some garden favorites are hardy perennials, like foxtail fountain grass (Pennisetum alopecuroides), but in milder western climates tender perennial forms, like purple fountain grass (Pennisetumsetaceum ‘Rubrum‘), will survive several seasons, too. Perennial forms don’t die back and are long-lived. Pennisetum such as these are displacing less aggressive native species in low, moist areas.
The same applies to your yard. If the seeds fall near irrigation heads, they sprout into weeds. It may have been open ground, but now it’s become a longterm weed problem. Such introductions are hard to stop and take a few seasons of dedicated handwork to clean out.
Runner Grasses
Runner grasses, like Japanese bloodgrass (shown) and Bermuda grass, will invade and become intertwined with perennials and other ornamental grasses.
Runner grasses spread, unlike stayput bunch grasses. The common southern lawngrass, Bermuda grass (Cynodon dactylon), is the poster child for a host of aggressive runner grasses that spread fast and invade perennials and well-behaved bunchgrasses. Another ornamental grass to add to the equation is Japanese bloodgrass (Imperata cylindrica), with its red-tipped blades and fast-spreading runners that will quickly overtake moister beds. The problem is the worst when runner grasses overtake bunch grasses. They creep unseen beneath a garden grass, and then once well rooted, the runner grass becomes nearly inextricable. If the bunchgrass is large and broad, the two grasses will forever be bound together, foliage plaited into a nest, and there’s no separation once established. Prevention is everything. Beware adding these, or any aggressive runner grass, to your yard or garden.
Short-Lived Grasses
This fine-textured Mexican hair grass in full flower and nodding in the breeze. (Photo by Maureen Gilmer)
Grasses are ephemeral plants by nature, adapted to range fires in the wild, grazing, floods, and landslides. Those that evolved with a long life span prove that they have adapted to climate change, since well before the Pleistocene, and are still super adapted for the future. The most long-lived, resilient grasses to grow in arid gardens are native deer grass (Muhlenbergia rigens) and its kin (Muhlenbergia group). But, more short-lived species, such as the windswept Mexican hair grass (Nassella tenuissima) or purple fountain grass, die out in just a few years.
Clump Splitting
These newly planted blue fescues have not suffered crown split yet.
Early in the life span of blue fescue (Festucaglauca varieties), the mounds of icy blue needles are perfect hemispheres. Like many other grasses, fescues grow too tall and heavy then split down the middle, allowing light to reach the root crown at the center of the clump. The direct sun sears those formerly shaded crown stems, causing premature aging while the rest of the plant is perfect. Replacement is often required if the plants are depended upon to create full geometric domes. This is a natural process for fescues, so they are best planted with other species that take up the slack visually if they decide to split.
Midwinter Decline
In warm-winter climates, grasses are cut back midwinter, in colder ones, late winter. (Photo by Maureen Gilmer)
As dramatic as sweeping monocultures of grasses are, they are best used with ever-beautiful support plants due to an unattractive period in midwinter, even if not fully dormant. The grasses are routinely cut back to just a few inches to simulate a cold event. This removes dead and dormant growth as well as detritus inside the clump to make way for the renewal of foliage. To avoid the barren ground, it’s wise to choose other evergreen plants to carry this composition until green grass shoots start up again in spring. Renewal is part of grass biology, so cutting back is regenerative and makes them healthier overall.
Ornamental grasses are an important cornerstone of today’s arid-zone gardens. Those species adapted to warmer climates without summer rain offer a change in texture as well as wind-blown beauty in containers on porch or patio. They require lots of nutrition, so be sure to use Black Gold Moisture Supreme Container Mix when planting for efficient water-holding potential and water conservation. The best grass for containers and garden at higher elevations or further north are Miscanthus varieties, which ask for a bit more water. (Choose low-seeding or sterile forms, such as giant miscanthus (Miscanthus x giganteus).)
While shrubs and succulents can be inanimate, the slightest breeze begins the gentle sway of a thousand soft grass blades. The animation of the nodding flower spikes liven up a dying landscape in the dry autumn winds.
“When planting, is it good to mix potting soil with earth soil?” Question from Pamela of Richmond, Indiana.
Answer: Don’t waste potting mix on in-ground plantings. Add products created to be garden amendments instead. These contain the ingredients that gardens need, while leaving out unecessary components, like perlite, vermiculite, and other additives, that don’t benefit garden soils. Potting mixes are also typically more expensive when purchased in quantity.
The best ground soil additives for long-term fertility include compost, earthworm castings, fortified garden soil, and Canadian sphagnum peat moss, among others. All of these additives lighten the soil, increase organic matter, water-holding ability, increase drainage, and up plant performance. Some, like earthworm castings, also add natural nutrients and beneficial microbes.
Beneficial fungi, called mycorrhizae, are another good soil additive. They work beneficially with plant roots to help them take up more water and nutrients for better performance.
“What type of Black Gold soil is recommended for potting avocado seedlings?” Question from Rusty of San Diego, California
Answer: Excellent drainage is one of the most important attributes of soil for avocado growing. They cannot endure wet soil for any period of time without being subjected to root rot. This means planting them in very well-draining pots as well as planting them in a porous mix that drains well while holding enough moisture for good growth.
Robust avocado seedlings grow quickly, so there is no need for a fine, seed-starting mix. Avocados also prefer soil with a near-neutral to slightly acid pH of 6 and 6.5. Based on these needs, I would recommend growing your avocado seedlings in Black Gold Natural & Organic Potting Mix. It is OMRI Listed for organic gardening, fast draining and fertile, and it maintains the correct pH for your avocados. Follow up with a good fertilizer formulated for avocados and you should be set.
“The rainfall this year has been incredible and my window boxes are showing it. I usually take off the top of the soil each year and replace it with new soil but this year there is a lot of moss. I would like to know if I should just remove all of the soil and treat the containers or if I can just scrape the moss off and top the boxes off with new soil before planting.” Question from Melissa of McDonough, New York
Answer: All potting soil breaks down over the years, losing aeration, structure, fertility, and drainage capacity. The dense organic matter of old potting mix just sits at the bottom of pots and slows drainage. Mixes also tend to acidify as they age and break down. Moss grows best on more acid soils that are moist and high in organic matter, which is probably why your boxes have more moss than average.
Simply topping off your window boxes yearly will encourage shallow rooting because plants grow best in newer potting soil, and deep rooting encourages the best growth.
To avoid all of these problems, your potting mix should be replaced every two years or so. If mix from the previous year or two is not well aerated and porous when wet, then it’s time to replenish. (Instead of tossing old mix, I like to incorporate it into my beds as an amendment, so I don’t waste it.) In the process, make sure the holes at the bottom of your boxes are open and draining well. When replacing mix, it also helps to add an all-purpose, slow-release fertilizer.
“Have been using your Black Gold Cactus Mix and Perlite for about a year now. I am growing primarily succulents. When I started, I experimented with many different kinds of soil and your soil mixed with perlite gave me the best results. In Hawaii, my climate is hot and humid. I have noticed lately that the soil is becoming hydrophobic. Is there any solution to this problem or ways that I can avoid this from happening? I really love your soil and would want to avoid this with future planting. Thank you.” Question from Patti of Mililani, Hawaii.
Answer: Yes! There are several things you can do to make dry soils moist again.
If the soils in your pots are repelling water, I suggest incorporating some Black Gold Peat Moss Plus or Black Gold Just Coir into your mix. Both products soak up water well and Peat Moss Plus contains an added organic wetting agent to keep soil water retentive. I also suggest adding a pebble layer on top of pots to help keep moisture in the mix.
For bagged soil, seal your bags well after use to keep the soil from getting dry. You can even add a little extra water to the mix and blend it by hand before sealing it. The ambient heat should help re-wet the mix.
