HOW TO PLANT FENNEL

If you want to enjoy fresh fennel from your garden, start by planting the seeds properly. Here’s what you need to do.

To plant fennel, sow seeds 1/4 inch deep in well-drained soil. Space seeds 4 to 6 inches apart in rows that are 18 inches apart. Fennel seeds thrive in soil with a pH of 6.0-7.0 and germinate in 7 to 14 days. For a steady harvest, plant seeds every 3 to 4 weeks.

Fennel is primarily propagated through seeds. For the best results, read on to learn more about planting fennel seeds and proper planting techniques.

GROWING FENNEL FROM SEED

Fennel does not produce the kind of bulbs that divide to create more plants. Rather, it depends on its fallen seeds to propagate new plants. It is best to use fresh, high-quality seeds to ensure good germination rates. Fennel seeds can easily remain viable for 3 to 4 years. If you buy them from a grocery store baking aisle in the spice section, there is no way to know how old the seeds are. In general, plant nurseries don’t want bad reviews because their seeds don’t sprout so they will sell newer seeds that are usually viable with a high germination rate.

Fennel seeds do not require cold stratification. They should be planted directly into the soil, about 1/4 inch deep, after the last frost date. Planting fennel seeds shallowly is essential for several reasons. Fennel seeds are small and need to be near the soil surface to have enough energy to break through. Also, the top layer of soil is the warmest so it promotes faster germination. Fennel seeds germinate best at soil temperatures between 60-70°F (15-21°C).

Shallow planting helps ensure fennel seeds have sufficient moisture to germinate. Keep the soil consistently moist but not waterlogged during the germination period, as too much or too little water can impede growth.

THE BIG DIG ON DIRT FOR FENNEL

Choose a fennel growing location that receives full sun, at least 6 to 8 hours of direct sunlight per day. Ensure the soil pH is between 6.0 and 7.0. You can test this at home and adjust the pH if necessary. To increase soil pH, add ground limestone (lime), which is available as dolomitic lime (containing magnesium) or calcitic lime (primarily calcium). To decrease soil pH, add sulfur, peat moss, or ammonium sulfate.

Fennel roots can extend 12 to 18 inches deep and spread horizontally, depending on soil conditions and plant health. To support robust growth, prepare the soil within this depth and width, ensuring it is well-aerated and nutrient-rich. Loosen the soil, removing rocks and debris, and incorporate organic matter like compost or well-rotted manure to improve fertility, drainage, and structure. This provides a slow nutrient release that energizes fennel as it grows.

By preparing the soil to a depth of 12 to 18 inches and ensuring it is fertile, pH-balanced, and well-drained, you will provide an optimal growing environment for fennel that supports healthy root development and plant growth.

STARTING FENNEL INDOORS

You can get a head start on fennel by planting indoors when it is still cold outside. Start fennel plants indoors 4 to 6 weeks before the frost-free date for your area. Seeds usually germinate in 7 to 14 days.

Perhaps you’d like someone else to do the indoor planting for you. Read on to see how to purchase the best fennel from a nursery.

BUYING FENNEL FROM THE NURSERY

When buying fennel plants from a nursery, here are key factors to look for to ensure you select healthy plants:

1. Healthy Foliage:
   • Color: Look for vibrant, green leaves without yellowing, browning, or spots, which can indicate nutrient deficiencies or disease.
   • Texture: The leaves should be firm and crisp, not wilted or limp.
2. Strong Stems:
   • Structure: Choose plants with sturdy, upright stems that are not leggy or excessively thin.
   • Damage: Avoid plants with broken, damaged, or excessively bent stems.
3. Root Health:
   • Root Bound: Gently check if the plant is root-bound (roots tightly circling the pot). While some root circling is normal, excessive root binding can stress the plant.
   • Color and Texture: Healthy roots should be white or light-colored and firm, not brown, mushy, or rotten.
4. Pest-Free:
   • Inspection: Carefully inspect the plant for signs of pests such as aphids, spider mites, or caterpillars. Look under the leaves and along the stems.
   • Residue: Check for sticky residue, webbing, or holes in the leaves, which can indicate pest presence.
5. Disease-Free:
   • Spots and Discoloration: Avoid plants with black spots, mold, mildew, or other signs of disease on the leaves or stems.
   • Overall Vigor: Choose plants that look healthy and vigorous, not stunted or weakened.
6. Size and Maturity:
   • Proportion: Select plants that are proportionate in size for their container. Overly large plants in small pots may be stressed.
   • Development Stage: Ensure the plant is at the right stage for transplanting, neither too young nor too mature.
7. Nursery Conditions:
   • Reputable Source: Buy from a reputable nursery with good plant care practices and knowledgeable staff.
   • Growing Conditions: Check that the plants have been grown in suitable conditions, such as appropriate light levels and proper watering.

By paying attention to these factors, you can choose healthy fennel plants that are more likely to thrive in your garden. Keep in mind that, even though you are buying from a nursery, the plants have probably been grown in a protected, indoor area and will still need to be hardened off.

TRANSPLANTING ESTABLISHED FENNEL PLANTS TO YOUR GARDEN

Hardening Off Fennel Plants:

When it is time to plant the fennel, gradually acclimate established plants to outdoor conditions before planting by leaving them outside. To acclimate a plant to outdoor conditions before planting it in the garden, follow these steps to help to reduce transplant shock for the fennel:

1. Start in a sheltered area: Place the plant outside in a shaded, sheltered spot for a few hours a day. Increase the time it spends outside over a week.
2. Gradually increase exposure: Each day, expose the plant to a bit more direct sunlight. Start with early morning or late afternoon sun to avoid intense midday heat.
3. Monitor and adjust: Keep an eye on the plant for signs of stress, such as wilting or leaf burn. If needed, reduce exposure time and increase it more slowly.
4. Protect from wind: Wind can be harsh on new plants. Shield them from strong winds, especially in the first few days.
5. Water appropriately: Ensure the plant stays hydrated but not waterlogged. The soil should be consistently moist.

Planting the Fennel:

Transplant fennel plants into the garden once frost risk has passed and the plants have had time to acclimate to living outside. Prepare the soil as described under the ‘The Big Dig on Dirt For Fennel’ heading above. Dig a hole slightly larger and deeper than the plant’s root ball. Wet the bottom of the hole so the roots have immediate access to water. Carefully remove the plant from its pot, trying not to disturb the roots too much. If the plant is root-bound, gently tease apart the roots to encourage spreading. Place the plant in the hole, ensuring the crown is at soil level or slightly higher. Fill the hole with soil, firming it gently around the roots to eliminate air pockets. Fennel plants should be placed 8 to 12 inches apart in rows that are 18 inches apart.

After–Care for Fennel Transplants:

Water your fennel plant thoroughly after transplanting. Keep the soil consistently moist but not waterlogged during the establishment period. Applying a 2 to 3 inch layer of mulch around the base of the plant, will help to retain moisture, regulate soil temperature, and suppress weeds. However, keep mulch a few inches away from the plant’s stem to prevent rot.

WHEN TO PLANT FENNEL

Fennel is moderately cold-hardy but not fully frost-tolerant. Fennel is generally ready for bulb harvest 3 to 4 months after planting. In colder zones, plant fennel in spring after the last frost to give it the entire growing season to establish. In milder climates, you can also plant fennel in the fall for a winter harvest. Here is a breakdown of approximately when to plant fennel seeds according to various USDA growing zones:

USDA GROWING ZONE	OUTDOOR SOWING	INDOOR SOWING
Growing Zones 3–4	Late May to early June.	Sow indoors 6 to 8 weeks before the last frost date (March to April). Transplant after last frost.
Growing Zones 5–6	Late April to early May	Sow indoors 6 to 8 weeks before the last frost date (February to March). Transplant seedlings outdoors in late April to early May.
Growing Zones 7–8	Late March to early April.	Start seeds indoors 6 to 8 weeks before the last frost date (January to February). Transplant seedlings outdoors in mid-March to early April.
Growing Zones 9–10	Early to mid-February	Starting seeds indoors is usually unnecessary, but if desired, start them 4 to 6 weeks before the last frost date (December to January).
Growing Zones 11–13	October to February	Generally not needed, but if desired, seeds can be started indoors in cooler months and transplanted when the weather is mild.

GROWING FENNEL FROM YOUR SPICE CUPBOARD SEEDS

While it can be an interesting experiment to plant fennel seeds from your spice cupboard, for the best results and higher germination rates, it’s generally recommended to use seeds specifically sold for planting.

Though it isn’t my favorite method, I know some will want to try it, so HerbDigger.com will cover the ‘How-To’s’ of spice cupboard fennel planting here. It is possible but comes with some caveats:

Keep in mind a few things before you begin. Fennel seeds from the spice cupboard may not be as viable as seeds specifically sold for planting. They might have been processed or treated in ways that reduce their germination rate. Look for seeds that are untreated and organic to avoid this. Even if the seeds are viable, their germination rate might be lower than that of seeds purchased from a garden center or seed supplier. And be aware that seeds lose their viability over time. If the seeds in your spice cupboard are old, they are less likely to germinate.

Fennel Seed Germination Test

To check the viability of spice cupboard fennel seeds, you can perform a simple germination test. Place a few seeds on a damp paper towel, fold it over, and keep it in a warm, dark place. Check after a few days to see if any seeds have sprouted. You can plant the seeds that sprout according to the directions above.

GROWING FENNEL FROM A FENNEL BULB

Creating a new fennel plant from a bulb by placing it in water is not a widely recognized or recommended method for propagating fennel. Typically, fennel is grown from seeds or seedlings. However, some gardeners experiment with re-growing fennel from the base of the bulb. Here is a video of one gardener with some tips on growing fennel from a bulb.

This method is more commonly used for some vegetables like celery or green onions and is not guaranteed to work for fennel, as it may not produce the robust growth needed for a full plant. For more reliable results, it’s best to start fennel from seeds or seedlings.

HOW MUCH FENNEL SHOULD YOU PLANT?

Plant fennel every 3 to 4 weeks to ensure a continuous supply. You can calculate how much fennel to grow by how often you eat it. Recommended serving size is 1/2 cup raw fennel (1 bulb) for two people (source).

COMMON MISTAKES AND HOW TO AVIOD THEM

• Poor Soil: Ensure soil is well-drained and fertile. Avoid planting in heavy clay or compacted soil.
• Incorrect Spacing: Space plants adequately to prevent overcrowding and ensure good air circulation. Keep in mind that fennel can grow to be around six feet tall and about two feet wide.
• Depth Issues: Plant seeds at the correct depth (1/4 inch) to ensure successful germination. Prepare the soil to a depth of 12 to 18 inches and width around where your fennel will be growing.
• Sunlight: Ensure plants receive full sun. Lack of sunlight can lead to leggy growth and reduced yield.
• pH Neglect: Regularly test and adjust soil pH to stay within the optimal range (6.0 to 7.0).
• Ignoring Companion Planting: Be aware of plants that may negatively affect fennel’s growth. See our article on companion planting for fennel HERE.
• Neglecting Weeds: Control weeds when plants are young. Mulch plants with straw or lawn clippings to prevent weed growth and help maintain cool and moist soil conditions.

HAPPY GARDENING!

Congratulations on learning how to grow fennel! With what you’ve learned here you’re well on your way to a successful harvest. Remember to keep your soil well-prepared, maintain consistent moisture, and provide plenty of sunlight. With a little care and attention, you’ll enjoy fresh, flavorful fennel from your garden harvest.