We are getting close to the typical average last frost date at March 3rd. So now is the time to start some cucumber, squash or melon seeds indoors.
Starting Mix
First, you need some seed starting mix. You can use ready-made mixes, or you can make your own by using potting soil mix you have on hand. Since I always have some potting soil mix on hand for use in containers or up potting starts, I use that. I suggest screening it through a ¼ inch hardware cloth sieve to take out any larger pieces which might block the seeds from poking through the mix.
Once the soil is hydrated, add it to the seed trays. Since cucumber, squash, and melon seeds are larger seeds, they are planted at about twice their size or roughly ½ inch depth.
Next, place your starter tray on a rack or designated place, covering it with a humidity dome. If you have plant-start heating mats, they can be very helpful by warming the soil, but are not absolutely necessary. It is customary to “bottom” water seeds, so add water to the tray your seeds are in. The soil should be moist enough from the initial wetting process described above, thus only a little water should be needed in the tray. Add water only when soil dries out slightly. After about 15 minutes, if any water remains in the tray, drain it. The humidity dome should stay on until the seedlings begin to show.
Seedlings
The Armenian cucumber seeds in these photos germinated over five days from February 17th through the 22nd with the humidity dome being removed on February 22nd.
At this point the seedlings should be placed under grow lights slightly above their height. Adjust the height of the light as the seedlings grow. If the grow lights are too high, the seedlings will likely become “leggy,” because they are stretching to reach more light. This will cause them to be weaker due to the main stem being too long and thin, and likely top heavy. The first set of leaves on the seedlings are the cotyledon leaves. The next set of leaves you will see are the first true leaves and the cotyledon leaves will likely drop off.
Preparing Plants for the Garden
Hardening off is the process of acclimating the new seedling to the outdoors. This starts by moving them outdoors the first day for perhaps 2 hours. This continues daily, increasing amount of time of outdoor exposure each day for about 1 week. By then your new starts should be able to handle being transplanted into your outdoor garden.
If you prefer not to jump start your growing season by starting seeds indoors, cucumbers, squash, and melon seeds can be started in the ground in late March. Just be sure to check the long-range weather forecast to see if any possible freezing temperatures might happen.
Tim Long has been a UC Master Gardener in Stanislaus County since 2020. All photos are by the author.
/h3>/h3>/h3>- Author: Maggie Mah
Growing your own plants from seed has a lot of advantages: more variety, less cost and getting a head start on the growing season are just a few. Practicality aside, it's just plain miraculous to grow plants from seeds. The process of putting hard, dry, seemingly lifeless bits into soil and seeing the transformation to a living plant is fun, fascinating, and forms an amazing connection to the natural world. Some seeds can be sown directly into the ground, but others benefit from a gentler, more controlled beginning and February is the perfect time to get started. If the rows of colorful seed packets are enticing but the idea of growing anything from seed seems daunting, fear not. If previous attempts have been disappointing, fear not. Here's what you need to know to get growing:
How Seeds Work
It can be as big as a coconut or as small as a speck of dust, but every seed is a plant waiting to happen. On the outside is a protective covering known as a “coat.” On the inside is the “germ,” a tiny embryonic plant with a root, stem and one or more leaves. Surrounding the germ is nutritive tissue or “endosperm,” which sustains the incipient plant.
When soil temperature is right and sufficient moisture is available, the seed coat allows water and air to infiltrate, and the germination process can begin.
A tiny stem stretches upward, the Cotyledons unfold, turn green and disappear once the plant develops true leaves.
What Seeds Need
Three things are needed for germination: the right temperature, abundant moisture and sufficient oxygen. Too much or too little of any one of these factors will not lead to success.
Choices, choices
Unlike commercially grown seedlings, which are usually available in only one or two varieties, growing from seed gives you a much wider selection of varieties and allows you to select plants for conditions in your location. When selecting tomatoes and other seasonal crops, pay close attention to “Days to Maturity,” the term for the number of days it will take to produce fully ripened or mature produce. Varieties with fewer days to maturity are best for cooler, foggier areas. Be sure to use seeds from a reputable supplier and check the expiration date before purchase.
Plan Ahead
Decide the number of plants you want to end up with when your seedlings are ready to transplant. Factor in that some seeds will fail to germinate and that some seedlings will not be sufficiently robust to “graduate” to the garden.
In general, seeds should be started 6-8 weeks before the date you want to transfer to the garden. Starting too early can easily lead to your seedlings becoming root-bound so if in doubt, wait a week or two. Please refer to UC Master Gardener Planting Calendar: https://smsf-mastergardeners.ucanr.edu/Edible_Gardening/
For ornamentals, pollinators and other non-edibles that can be started from seed indoors, refer to the seed packet for timing.
Seed Starting Basics
Soil
Use a blend specifically formulated for starting seeds. It should be light and uniform in texture, sterile and nutrient rich. Never use “native” garden soil and avoid regular potting soil. Make sure soil is evenly moist prior to seeding.
Containers
Just about any kind of container will work if it is clean and has drainage holes. “Clam shell” food containers, yogurt cups and other plastic packaging can be re-purposed along with nursery “six packs” and 4-inch pots. Wash, rinse and sterilize by spraying with a solution of 1 part chlorine bleach to 9 parts water and air dry before using. You can avoid containers altogether by using soil blocks. (See below for more information.)
Seeding
Fill your containers about 2/3 full of soil and follow seed packet directions for planting depth and spacing. Seeds that are started closer together will require “up-potting” and/or thinning at a later stage. Note: some plants, such as squash, don't like that kind of disruption and should stay in individual containers until transplanting time.
Watering
Moisture is essential for germination and watering is best done from the bottom to avoid dislodging newly planted seeds. Place seeded containers in a solid tray that will hold water. (Concrete and mortar mixing trays are ideal.) Add water to the bottom of the tray to a depth of approximately ½ inch. Seed containers should be checked frequently to make sure the soil is evenly moist but not wet or soggy. Adjust the amount of water added to the tray to maintain adequate moisture while avoiding standing water for more than a few hours. Clear plastic covers help to retain moisture as does a light topping of vermiculite.
Provide light and warmth
Find a spot with bright, indirect light such as a sunny window and where temperature is between 65 and 70 degrees during the daytime and 55-60 at night. If the perfect spot is not to be found, consider using grow lights and specially designed heating mats for plant propagation. Both are inexpensive and energy efficient.
Growing
Maintain proper moisture, light and warmth and in 6 to 21 days, seedlings will start to emerge. First to appear are the tiny green cotyledons that have burst forth from the seed. As soon as the true leaves appear, seedlings can be “up-potted” to larger containers.
“Hardening Off”
Young plants that have been grown indoors require gradual exposure to outdoor conditions. About two weeks before transplanting and when night time temperature has reached 50°, start the process by moving plants outside to a shaded location during the day and bringing them inside at night. After that, gradually increase the amount of sun exposure during the day and allow plants to remain outside at night.
Transplanting
When plants have been hardened off, it's time to plant! Prepare beds well ahead of time, then dig holes the size and depth of the seedling pot (deeper for tomatoes). Allow adequate spacing for the size of the mature plant. Invert the pot, allowing the seedling to pass through your fingers and gently grasp the root ball. Invert and set the plant into the hole. Gently tamp down, adding more soil if necessary. Water carefully and finish by adding a layer of mulch.
It's no wonder that seeds and the act of planting are the basis of so many sayings and inspirational words. Whatever seeds you decide to sow, you will be part of an amazing, eternal process of renewal.
Any questions? Contact the Master Gardener Helpline: http://smsf-mastergardeners.ucanr.edu/
For more on soil blocking: https://smsf-mastergardeners.ucanr.edu/?blogpost=55580&blogasset=125102
For more on soil preparation: https://mg.ucanr.edu/Gardening/Vegetable/Preparing/SoilImprovement/
Maggie Mah is a UC Master Gardener who is fascinated by seeds.
UC Master Gardeners of San Mateo-San Francisco County are volunteers who are trained under the auspices of the University of California to provide science-based information on plants, horticulture, soil and pest management at no charge to the public. For more information and to find out about classes and events in your area, visit our website where you can also sign up for our newsletter: http://smsf-mastergardeners.ucanr.edu/
Springtime planting is almost here but don't rush to plant seeds until the soil has warmed up! Planting seeds too soon, when the soil is cold and wet, risks losing them to damping-off, a disease caused by fungi and oomycetes in the soil. Learn more about this common disease in the newly updated Pest Notes: Damping-off Diseases in the Garden written by UC IPM Director Dr. Jim Farrar and UCCE emeritus advisor Ed Perry. They cover the biology of the pathogens, identification of the disease, and how to prevent damping-off when growing transplants or seeding directly into the ground.
Timing is everything
As much as warm winter days (and glossy seed catalogs) may tempt us, Morgan Hill gardeners are wise to wait. According to the almanac of farming fame, Morgan Hill's last frost date is Feb. 15, while the National Oceanic and Atmospheric Administration (NOAA) warns that gardeners have a 10 percent chance of freezing temperatures as late as March 20! Starting too soon is simply a waste of time and seed.
Seed selection
Before planting, decide what you want to grow. Browsing seed catalogs can be intoxicating. Rather than ordering everything that looks good, find plants that are suitable to your microclimate, won't need a lot of water, and are non-invasive.
Read the label
Most seed packets are a wealth of valuable information that includes an image of the plant, description, and any special needs. Labels also list the year, timing, planting depth and spacing, thinning, sunlight, and watering needs of each plant. Use this information and save it for future reference.
Soil selection
Some seeds can be planted directly into the ground. This is called direct sowing. While all growing areas will serve your plants better if they are regularly fed with aged manure and compost, this is especially true for seeds and seedlings. They have a lot of work ahead of them and need all the nutrients they can get their little root hairs into. Most seeds are better off started in small pots filled with high-quality potting soil or starter mix.
Select containers
Starting seeds in small containers is the easiest way to begin. Placing one seed into each small container allows tiny roots to develop unchallenged. It also makes transplanting less stressful. You can reuse plastic seed starting pots, called "cell flats" from when you buy seedlings. Remember to clean and disinfect flats to avoid spreading pests or diseases. You can make biodegradable planting containers from paperboard egg cartons, newspaper, or toilet paper tubes, or you can buy seed starter pots. Take-out food containers, with clear plastic lids, can also be used for seed starting. The plastic covers keep warmth and moisture in.
Start planting
Once you have collected your seeds, containers, and potting soil, you are ready to plant. Labels made from Popsicle sticks are very handy, too. Labeling is important because many young plants are difficult to tell apart until they are long past the transplanting stage. Follow these steps for successful seed starting:
- Fill all containers loosely with potting soil, tamping it down gently.
- Place one seed in the soil to the depth specified on the packet.
- Add a dated plant label to each pot.
- Place flats on a water-resistant surface that will receive six to eight hours of sunlight each day, where they will be safe from slugs and snails.
- Gently and thoroughly water the flats. For seeds left on the soil surface, use a mister to water, to avoid washing them away, or pushing them too deeply into the soil. Soil should be kept moist, but not soggy, until the first true leaves are seen.
- Some plants, such as peppers, may need extra heat from a heating mat.
Now the seeds are started and waiting begins. Use this time to prepare your garden beds, raised beds, containers, towers, and other planting areas so they will be ready when it is time for transplanting,
Stop by the Spring Garden Market from 9 a.m.–2 p.m., April 14 at Martial Cottle Park for spring planting needs.
by UC Master Gardener Kate Russell
This article first appeared in the March 14 – 27, 2018 issue of Morgan Hill Life.
Benefits of seed starts
Some plants, such as lettuce, have tiny seeds that need light to germinate. Planting these directly in the ground often leads to losses due to wind dispersal or rotting under too much soil. Starting these plants in containers makes it easy to monitor them and keep the soil moist until the seeds sprout.
As seedlings grow, they can become root bound, which means the roots start wrapping around the inner wall of the container. Before this happens, you can up-pot or transplant those seedlings. Up-potting means moving a seedling from a small container to a slightly larger one. Transplanting means moving the plant to where it will live out its life.
When not to transplant
Plants that are fruiting, flowering, infested, or infected should generally not be transplanted. New transplants need to be able to focus on building strong root systems. Also, just as some people are more sensitive than others, some plants do not take kindly to being transplanted. The following plants should be sown directly into the ground whenever possible: artichoke, beans, beets, butternut squash, carrots, corn, cucumber, dill, melons, onions, peas, radishes, summer squash and zucchini.
How to transplant seedlings
For many vegetables, you can transplant seedlings with the first leaves below the soil line. Very often, these meristem tissues will transform into root tissues, adding nutrients to the plants. Once the seedlings are a couple of inches tall, prepare their new home, making sure the soil is loose.
The South Bay's heavy clay can form an impenetrable barrier to new roots if it is left smooth from a trowel or shovel. Be sure to rough up the edges of the planting hole. Then, follow these steps to successfully transplant the seedlings:
1. Place your hand over the container with the plant between your fingers.
2. Gently turn the pot on its side or upside down, tapping the bottom with your other hand to knock the soil loose.
3. Cup your first hand to hold onto as much of the soil as possible.
4. Examine the roots and spread them out if they have started wrapping around themselves.
5. Slowly turn your hand, allowing the root system to roll into the hole.
6. Ensure all roots are covered with soil. If peat pots were used, make sure all of the peat is covered, as well.
7. Gently pat the soil down to eliminate any big air pockets. (Most roots don't like being exposed to air.)
8. Water thoroughly.
Caring for new transplants
New transplants should be treated gently for a few days. To help a young seedling thrive in its new environment, in a process called ecesis, be sure to:
Harden off seedlings before transplanting; water regularly, allowing the soil to dry out between waterings; do not use insecticidal soap or other treatments right away; feed transplanted seedlings with fish emulsion or phosphorous a few days after their ordeal; protect seedlings against cutworm damage by inserting a paperboard ring a couple of inches into the soil; provide wind protection by cutting the bottom out of large plastic jugs and placing them over vulnerable plants.
Visit the South County Teaching and Demo Garden, at St. Louise Hospital, 9400 No Name Uno. For more information, visit Events and Classes or call (408) 282-3105 between 9:30 a.m. to 12:30 p.m.
by UC Master Gardener Kate Russell
Photo: Copyright © 2016 The Regents of the University of California. All Rights Reserved.
This article first appeared in the May 24 – June 6, 2017 issue of Morgan Hill Life.