Frequently Asked Questions
Johnny's knowledgeable Customer Care representatives are always happy to answer your questions. Here are some of the the questions we are asked most frequently about gardening, our website, and our catalog.
If you don't find the answers you seek here, give us a call at 1-877-564-6697!
- What do references to "Zones" mean, and how do I determine which Zone I'm in?
- What kind of vegetables, flowers, and herbs can I grow in my zone?
- What kind of onions should I grow?
- What is a hybrid? Is it the same as genetically engineered (GE or GMO)?
- Do you sell open-pollinated (OP) varieties? How do I know which are OP?
- Can I save seeds and use them next year?
- What is the shelf life of seeds?
- How should leftover seeds be stored?
- How can I tell if old seeds are still viable?
- How much can I plant with Johnny's seed packets?
- How do I know how much seed to buy for the space I have?
- What can I grow in my shady yard?
- Can I start seeds without a heat mat?
- Do tomatoes need to be pruned?
Zones refers to geographic regions of plant hardiness, which are based principally on the average annual minimum temperatures. There are 11 hardiness zones in North America: Zone 1 is the coldest, with minimum temperatures of -50°F, and Zone 11 the warmest, with minimum temperatures never going below 40°F.
Plant hardiness is rated by the lowest temperature at which the plant can survive. For example, if a plant is described as being "hardy to Zone 5," that means it will survive in areas where the winter temperatures go as low as -20°F/-26°C.
The USDA Map of Hardiness Zones allows you to click on your area to find your zone and a list of the lowest temperatures that can be expected. Or, you can determine your zone by zip code and learn more about plant hardiness zones by visiting the website of the National Gardening Association.
You can grow most of what we feature in Johnny's catalog, no matter what zone you're in. That's because most vegetables, flowers, and herbs are annuals that complete their life cycle in one year and are therefore not affected by winter's low temperatures. There are exceptions, however; for example, flowers and herbs that are listed as perennials or biennials that don't flower until the second year; in the latter case, the product description will provide the hardiness zones in which the plant can be grown. See above for information about finding your zone.
In the US, onion varieties are traditionally described as being "short day" varieties for the South, or "long day" varieties for the North. Growers in the middle latitudes of the US can find these terms confusing when choosing which varieties are likely to grow most successfully in their area. Johnny's improves upon those terms by providing each variety's adaptation by latitude. If you don't know your latitude, you can find it by clicking on your location in Google Maps.
No, hybrids are not the same as genetically engineered varieties. Johnny's does not sell any genetically engineered varieties. To learn more about Johnny's position on genetically engineered crops, see our Safe Seed Pledge.
Hybrids are developed by the long, slow process of traditional plant breeding, which relies on natural reproductive methods. Hybrids are crosses between two or more parents with different desirable traits. Pollen from one parent plant is transferred to the flowers of the other parent plant. The seeds that develop are an F1, "first filial generation" hybrid.
Hybrids are identified by (F1) after the variety name. Johnny's founder and chairman, Rob Johnston, Jr., has written a description of the work that has gone into breeding several of Johnny's own varieties. It's a good way to learn more about the various procedures used in traditional plant breeding.
Johnny's sells both open-pollinated varieties (nonhybrids) and hybrids.
Hybrids are identified in the variety descriptions, usually by (F1) following the variety name.
In general, yes. But you need to know a few things to be successful. The first factor to consider is whether the plants you save seeds from are hybrids or nonhybrids.
- When you save seeds of hybrid varieties, the plants you grow from them will not be the same as the parent plant. This can lead to some interesting new variations, but you should not expect the saved seeds to produce plants like the preceding crop.
- If the plant is open-pollinated (nonhybrid), the seeds you save may produce identical plants next year. However, another consideration is whether the plants are protected from accidental cross-pollination by another variety. You can usually prevent cross-pollination by isolating crops from others of the same species. Every species has a required isolation distance, based on whether it's pollinated by wind or insects. Some crops can be protected from cross-pollination by row cover.
Because there are so many variables, much has been written about seed saving. For the basics, we recommend Growing Garden Seeds, by Rob Johnston, Jr. This inexpensive, 32-page booklet covers the 15 fundamentals of saving seeds.
Some seeds are viable only in the year of purchase, and others can be kept for many years.
If seeds have not been pretreated or pelletized, and if they have been stored properly, here is the shelf life you can expect:
- 1 year: onions, parsnips, parsley, salsify, scorzonera, and spinach
- 2 years: corn, peas, beans, chives, okra, dandelion
- 3 years: carrots, leeks, asparagus, turnips, rutabagas
- 4 years: peppers, chard, pumpkins, squash, watermelons, basil, artichokes and cardoons
- 5 years: most brassicas, beets, tomatoes, eggplant, cucumbers, muskmelons, celery, celeriac, lettuce, endive, chicory.
Storage conditions are very important to seed viability. Exposure to moisture causes seed viability to decline, so seeds should be stored in a dry place in an airtight, watertight container. Zippered freezer bags, glass jars, plastic containers, and metal boxes are all options, as long as they have a tight seal. Buckets with tight lids also work for larger seeds like beans and corn. In humid climates, a desiccant such as a packet of silica gel or dry milk powder can be placed in the container to absorb moisture. Seed also should be kept cool, and can even be stored in the refrigerator or freezer.
If you are in doubt about the viability of leftover seeds, there is no need to take chances. You can test the germination easily.
Simple Germination Test: Moisten a coffee filter or piece of paper towel and place on it a specific number of seeds, such as 10 or 100. Fold the moistened paper over the seeds and put it inside a plastic bag in a warm place. Take the paper out and inspect the seeds twice a day, spraying with water as needed to maintain moisture around the seeds. After the usual number of days required to germinate that variety, count to see how many have germinated and calculate the percentage of germination. Compare it to the germination rate on the Johnny's label; if it's close, your seeds are fine to plant. If germination is much lower or slower than expected, order new seeds.
The number of seeds in our packets varies by seed size and variety. You can find the number of seeds per packet listed in the Growing Information boxes below the product description. The seeding rate is also listed in the Growing Information box.
Johnny's Seed Calculator allows you to enter the vegetable variety and the row feet you plan to grow, then calculate you the number of seeds you'll need.
Virtually all vegetables require full sun; shade will generally reduce plant vigor and yield, if the plants grow at all. Some of Johnny's herbs and flowers can be grown in partial shade; impatiens is one of the few that can be grown in deep shade. The Growing Information box below each product description lists light requirements for each herb and flower variety. Because tree roots are often found near the soil surface in shady yards, growing in shade can be challenging. As an alternative, you may want to practice container-growing, placing your containers wherever sunlight filters through the trees for the longest period each day.
Absolutely. A heat mat helps seeds germinate quickly, but is not essential. After you have planted your seeds, place the container in a warm spot inside your house. Typical places include the top of the refrigerator, on a table above a radiator or heat vent, or near a wood stove. Cover with a clear acrylic dome, piece of row cover or even a plastic bag to retain moisture around the seeds, but check them often and remove the cover as soon as the seeds start to germinate. At that point, light becomes more important than temperature, and you should ensure that the seedlings are close to a grow light or on a sunny windowsill all day.
No, tomato plants will grow and produce fruit even if you don't get around to pruning them. However, you will get better yield and fewer disease problems if you prune them. Pruning is not difficult or especially time-consuming.
For more detailed guidance, watch Johnny's video on How to Prune Tomato Plants.