Question 1

A layer of gravel or pot shards at the bottom of a container improves drainage.

Accepted Answer

The old "never put gravel in the bottom of a pot" rule is overstated. A 2025 controlled test found a bottom layer usually drained soil-less mixes better and almost never made things worse, though in loam-based compost it mostly made no difference. It's one study and it grew no plants, so treat a layer as an option. It isn't a fix. If you use one, a thicker layer of coarse sand did best.

Question 2

Adding sugar or molasses to the soil makes tomatoes and other fruit sweeter.

Accepted Answer

Sugar in the soil won't sweeten your tomatoes. Fruit sugar is made in the leaves by sunlight. For sweeter fruit, you want a sweet variety, full sun, healthy foliage, and ripening on the plant (a little less water as it ripens helps concentrate it).

Question 3

Basil improves the flavor of adjacent tomatoes.

Accepted Answer

The one trial we know of found no difference in flavor, and nobody has proposed how it would work. Plant basil next to tomatoes anyway. You'll want them at the same time in the kitchen.

Question 4

Bone meal helps transplants and bulbs put down roots.

Accepted Answer

Bone meal isn't a rooting tonic. It's phosphorus and calcium, which most garden soils already have enough of, and phosphorus hardly moves in soil anyway. Too much can even stop roots teaming up with the helpful fungi they rely on. Get a soil test before adding any.

Question 5

Burying banana peels feeds plants potassium (roses in particular).

Accepted Answer

Banana peels do give up their potassium quickly, but a few peels are an unknown and probably small dose, and nothing shows roses need it. If you think a plant is short of potassium, get a soil test; otherwise just compost the peels.

Question 6

Burying rusty nails adds iron that greens up plants and turns hydrangeas blue.

Accepted Answer

Rusty nails won't green up your plants or turn hydrangeas blue. Yellow leaves usually mean high pH has locked the iron up. It isn't missing, and iron from a nail gets locked up the same way. Hydrangea blue comes from aluminum in acidic soil, not iron. Soil-test first; for yellowing, sulfur (where there's no free lime) or an iron leaf spray as a stopgap; to blue a hydrangea, add sulfur to the soil or use aluminum sulfate.

Question 7

Chives or garlic planted under a fruit tree prevent apple scab.

Accepted Answer

There's no evidence that chives or garlic under an apple tree prevent scab, and no mechanism for it. Scab lives in last year's fallen leaves and infects in wet spring weather. Choose a scab-resistant variety, rake up and bin the dropped leaves, and you've done the things that actually work.

Question 8

Cinnamon or chamomile tea prevents damping-off in seedlings.

Accepted Answer

Cinnamon and chamomile tea are popular anti-damping-off remedies because cinnamon is antifungal in a lab dish. But there's no good evidence either one saves a seed tray. What prevents damping-off is the setup: fresh sterile mix, clean pots with drainage, warmth and airflow, and going easy on the water.

Question 9

Coffee grounds acidify soil.

Accepted Answer

Coffee grounds haven't been shown to reliably lower soil pH, so they won't durably acidify your soil or make it blueberry-friendly. Put them in the compost, where they feed soil life; to lower pH, use elemental sulfur guided by a soil test.

Question 10

Coffee grounds scattered around plants repel slugs, snails, and other pests.

Accepted Answer

Coffee grounds scattered around plants haven't been shown to repel slugs or other pests. The idea comes from caffeine, which does kill slugs in a strong enough soil drench, but used grounds hold very little of it. Use beer traps, hand-pick at night, or put down iron-phosphate bait; put the grounds in the compost.

Question 11

Companion planting charts encode real relationships.

Accepted Answer

Most companion-planting advice you'll find online is folklore, and the charts have no scientific basis. A few pairings do have real mechanisms. Here's what we can actually defend, and why.

Question 12

Compost tea (or manure tea) greatly boosts growth and suppresses plant disease.

Accepted Answer

Compost tea isn't the tonic or disease cure it's sold as. The effects in the field are patchy, and aerated teas have no documented disease protection. Additives like molasses can grow E. coli and Salmonella, so keep it off food crops unless you're sure of the method. Spreading the compost itself as mulch is the better bet.

Question 13

Crushed eggshells deter slugs.

Accepted Answer

Crushed eggshells haven't been shown to deter slugs. Use beer traps, hand-pick at night, or put down iron-phosphate bait, which is safer around pets and wildlife. Put the shells in the compost for the organic matter. Their calcium releases too slowly to matter.

Question 14

Crushed eggshells in the planting hole prevent blossom-end rot.

Accepted Answer

Eggshells in the planting hole won't stop blossom-end rot. BER is a calcium-transport problem caused by uneven watering. It's rarely a soil-calcium shortage, and adding calcium to the soil is generally ineffective. Water evenly, mulch to steady the moisture, and soil-test before adding anything.

Question 15

Dish soap makes a safe, effective homemade insecticide, the same as insecticidal soap.

Accepted Answer

Dish soap isn't the same as insecticidal soap. Detergents strip the leaf's protective wax and can damage foliage, so the "safe homemade spray" idea backfires. If you want a soap spray, use a real insecticidal soap; it works on contact against soft-bodied pests like aphids.

Question 16

Epsom salts prevent blossom-end rot.

Accepted Answer

Epsom salts won't stop blossom-end rot. BER is a calcium-transport problem caused by uneven watering. A magnesium shortage doesn't cause it, and Epsom salts add magnesium, not calcium. Water evenly, mulch to buffer soil moisture, and soil-test before adding anything.

Question 17

Fresh manure is a safe, ready-to-use fertilizer you can spread straight onto the garden.

Accepted Answer

Fresh manure isn't a ready-to-use fertilizer. It can burn plants with ammonia and salts, and it can carry E. coli, Salmonella and Listeria. Leaving it in a pile doesn't reliably kill those; hot composting helps. Never put raw manure on growing food crops, and leave at least 120 days between raw manure and harvest for anything that touches the soil.

Question 18

Household vinegar is an effective weed killer.

Accepted Answer

Vinegar only burns the parts of a weed it touches, so it works on tiny seedlings, but bigger and perennial weeds grow back from the roots. It also harms any plant it hits, crops included. The strong "horticultural" kinds can burn skin and eyes. Use it for seedlings in paving cracks. It isn't a garden weed killer.

Question 19

If you buy good compost or bagged soil, your native ground underneath doesn't matter.

Accepted Answer

Buying good soil doesn't let you ignore the ground underneath. A few inches of good mix over poor soil keeps roots in that thin layer, so plants need more watering and feeding. Work amendments into your soil. Don't just lay them on top, and in shallow raised beds mix in the ground below.

Question 20

Marigolds repel most garden pests and protect the whole garden.

Accepted Answer

Marigolds don't protect the whole garden. Their best-known trick is underground. A dense planting of the right kind, grown at least two months before your crop, suppresses root-knot nematodes. Dotted among the vegetables, it doesn't work. Against insects the results are mixed. Some pests, like thrips and whiteflies, drop in trials; others, like Colorado potato beetles, don't budge. Grow them for color and treat any pest help as a bonus.

Question 21

Mixing sand into clay soil improves its drainage.

Accepted Answer

Don't add sand to clay to "loosen" it. In the amounts anyone actually adds, the clay fills the gaps and you get a denser, worse-draining mix. Work in compost and mulch instead; organic matter is what builds the structure that drains.

Question 22

More fertilizer means bigger, healthier plants.

Accepted Answer

More fertilizer doesn't mean bigger, healthier plants. Past what the soil is short of, the extra burns roots, pushes leafy growth at the expense of fruit, invites pests, and washes off into streams and lakes. Get a soil test and feed what it says the soil needs.

Question 23

Planting by lunar phase improves germination and yield.

Accepted Answer

No mechanism anyone can name, and the few small trials we found disagree with each other. Plant when the soil is warm and the frost risk has passed.

Question 24

Radishes deter flea beetles.

Accepted Answer

Radishes don't repel flea beetles. Flea beetles love radish, which is why some gardeners plant it as a trap crop to lure them off their broccoli and cabbage. That only works if you then deal with the beetles on the radish. If your radish leaves are riddled with tiny holes, that's flea beetles doing exactly what they do.

Question 25

Seeds saved from hybrid vegetables grow true to the parent plant.

Accepted Answer

Seeds from a hybrid won't grow true to the parent. You get a mix of plant types, most of them worse. If you want seed that comes true, save it from open-pollinated varieties, and keep them from crossing with other varieties of the same crop. Saving hybrid seed is a fun experiment, but it won't keep a variety.

Question 26

Spraying diluted milk on the leaves prevents or cures powdery mildew.

Accepted Answer

Milk spray for powdery mildew is one of the few home remedies with some trials behind it. Diluted milk sprayed before symptoms cut mildew on pumpkins, though a fungicide did as well or better in the field. It's a preventive at best. It won't cure mildew, and some extension services still doubt it. Start with resistant varieties and spacing for airflow.

Question 27

Spraying plants with dissolved aspirin boosts their immune system and health.

Accepted Answer

Aspirin spray isn't a proven plant tonic. There's a real kernel. Salicylic acid does switch on a plant defense response, and aspirin did it in the lab. But sprayed on, it's often toxic to the plant, it breaks down fast, and a dose that works on one crop won't carry to another. Treat aspirin as a curiosity, and don't make it a routine.

Question 28

Spreading cornmeal on soil or lawns cures fungal disease.

Accepted Answer

Don't use cornmeal as a fungicide. The idea comes from beneficial fungi that grow on it, but cornmeal itself feeds many fungi, pathogens included, and no published research backs it. Manage fungal problems with good drainage, sensible watering and airflow. Don't confuse it with corn gluten meal, a separate weed product.

Question 29

Sprinkling baking soda around tomato plants makes the fruit sweeter.

Accepted Answer

Baking soda won't sweeten your tomatoes. Sweetness is sugar the plant makes in its leaves. Nothing added at the roots has been shown to sweeten a garden tomato, and baking soda adds sodium, which in quantity damages soil. For sweeter fruit, you want a sweet variety, full sun, healthy leaves, and ripening on the plant.

Question 30

Sprinkling human hair, soap shavings, or urine around the garden reliably keeps deer and rabbits out.

Accepted Answer

Hair, soap and other home-remedy scents aren't a reliable way to keep deer or rabbits out. They need renewing, the animals get used to them, and deer have even eaten the soap. A fence is the dependable fix, and for deer it has to be tall. Store-bought repellents do better than home remedies, but most can't go on food crops.

Question 31

Talking to your plants, or playing them music, makes them grow better.

Accepted Answer

Talking to your plants won't grow them faster. You'd need to talk for hours a day for your breath to make a difference. Plants do respond to sound in the lab, but the music experiments are shaky and nothing shows a playlist helps a garden. Give them light, water and nutrients; chat to them if you enjoy it.

Question 32

Watering a little every day is the best way to water a garden.

Accepted Answer

Watering a little every day usually isn't best. It keeps roots shallow, so plants struggle when it's hot and dry. Water established plants slowly and deeply, and water again when the soil is dry an inch or two down. In most situations that works out to about once a week, but the weather sets the pace, so check the soil, not the calendar. There are real exceptions. Seedlings, new transplants, containers, sandy soil and shallow-rooted crops may need water much more often.

Question 33

Watering plants in the midday sun scorches the leaves (water droplets focus sunlight like lenses).

Accepted Answer

Watering in the midday sun won't scorch your leaves. Droplets don't focus sunlight on ordinary leaves. Water whenever the plant needs it, and aim at the soil and keep the leaves dry, because wet foliage invites fungal disease. Morning or evening watering just loses less to evaporation than the middle of the day.

Question 34

Watering with hydrogen peroxide oxygenates the roots and cures root rot.

Accepted Answer

Hydrogen peroxide won't oxygenate your roots in any lasting way. It breaks down in soil within hours, and it can harm the helpful life in the soil. It can kill some fungi, but root rot comes from waterlogged soil, and peroxide doesn't change that. Fix the drainage and ease off the watering.

Question 35

You must rotate every crop to new ground every single year.

Accepted Answer

You don't have to move every crop every single year by rule. What matters is keeping each crop family out of the same soil long enough to starve its diseases, commonly three to five years. Rotating yearly is a good habit. It isn't a law, and perennials like asparagus and rhubarb stay put for years.

Folklore, checked

Refuted

Contested