Tips for Growing Great Watermelons

Tomatoes aren’t the only stars of the backyard garden. Growing watermelons is just as rewarding. It’s also hard to resist all the beautiful varieties that you’d never find in a supermarket. However, watermelons can be trickier to grow than some other crops. Here are a few tips to help you grow watermelons this season.

Choosing a Variety

New gardeners, folks with small gardens, and those who live farther north may want to consider icebox melons or smaller melons with fewer days to harvest. Some great options include:

  • Sugar Baby Watermelon
  • Early Moonbeam Watermelon
  • Blacktail Mountain Watermelon
  • White Wonder Watermelon

Folks who’ve struggled with plant diseases in their garden should look at varieties with good disease resistance. Some options include:

  • Chou Cheh Red Watermelon (Downy Mildew resistance)
  • Crimson Sweet or Crimson Sweet Virginia Select (Anthracnose and Fusarium resistance)
  • Yellow Fleshed Moon and Stars Watermelon (some tolerance to disease)
  • Nancy Watermelon (Above-average disease resistance)
  • Strawberry Watermelon (Very good disease resistance)

Preparing Your Garden

Watermelons tend to be fairly particular about the soil they’re grown in. It’s a good idea to start by adding a few inches of finished compost to your plot.

The soil for watermelons should be well-drained and have a pH between 6.0-6.8.


The key to giving your watermelons a good start is to ensure that the soil is warm enough. Wait to plant melons until the soil temperature is around 70°F, probably about two weeks after your last frost date.

It’s a good idea to plant watermelons in hills; they don’t do well in soggy soil. Space watermelons 12-18 in. apart in rows 6-8 ft. apart. Vines require anywhere from 36-100 sq. ft. of vine space per hill, depending on the variety.


In order to get the best production, watermelons require good, consistent care.

  • Don’t disturb vines while the fruit is ripening, or else fruit may ripen unevenly.
  • Water consistently for good fruit production. Drip irrigation or soaker hoses are a great choice and can help prevent fungal diseases.
  • Mulch around watermelon hills with hay or straw to keep melons off the ground.
  • Keep up with weeds, especially before the vines start to sprawl.
  • When your plants are flowering, give them a boost with compost tea or other liquid fertilizer like liquid kelp.

Harvesting Watermelons

Your watermelons are looking great, but how do you tell when they’re ready to harvest? There are four clues you can look for:

  • The spot where the fruit touches the ground turns yellow.
  • The curly little tendril on the portion of the vine nearest the fruit should be dried -up and brown.
  • The rind feels slightly rough and ridged and has a dull, opaque appearance, whereas immature fruits are smoother and glossier.
  • When a watermelon is ripe, it will have a hollow sound when you thump it with your knuckles: The melon sounds more like your chest when it is ripe; when green, it sounds more like your head; when over-ripe, it sounds more like your stomach. Mark Twain described it this way: “A ripe melon says ‘punk’ when thumped, a green one says ‘pink’ or ‘pank’.”

Put Your Watermelons to Good Use

Eating fresh watermelon is probably everyone’s favorite way of eating enjoying it, but there are some other ways to get the most of your watermelon.

  • Watermelon seeds are edible, have a nutty taste, and are commonly sold as a snack in some parts of the world. Seeds that mature to black are easier to eat than white seeds.
  • Watermelon rinds can be pickled and eaten throughout the winter.
  • You can dehydrate watermelon into “watermelon candy,” freeze it for smoothies or try your hand at fermenting watermelon wine.

Common Nutrient Deficiencies in Plants

Spotting nutrient deficiencies in your plants can be challenging, especially if you’re new to gardening. Here are what a few common deficiencies look like and how to correct them.

Soil Nutrients

Nutrients in the soil can be divided into two categories macronutrients and micronutrients/trace minerals.

The first category, macronutrients, comprises primary nutrients nitrogen, phosphorus, and potassium and secondary nutrients sulfur, magnesium, and calcium. If you think your plant has a nutrient deficiency, these are the likely culprits.

The second category, known as micronutrients or trace minerals, includes boron, chlorine, copper, iron, manganese, molybdenum, and zinc. While these are still important to plant health, they’re needed in such small quantities that it’s less likely your plant is deficient in one of these micronutrients.

You can read more detailed descriptions of what all of these nutrients do in our post, Understanding Soil Tests.

Nitrogen Deficiency

A nitrogen-deficient plant will grow slowly and lack vigor. The leaves may turn pale and yellow before dropping off, with the oldest leaves dropping first.

Note that it’s easy to overdo it when adding nitrogen, especially if you’re using chemical fertilizer. Adding too much nitrogen will cause lush, dark green foliar growth at the expense of fruit and flower production.

There are many ways to add nitrogen to your soil. While you shouldn’t directly apply it to plants, animal manure is a good choice if you have access to it. Compost will also add some nitrogen, or you can add seaweed or kelp meal, fish emulsion, bone meal, coffee grounds, soybean meal, or cottonseed meal. Using legume cover crops also helps to increase your soil’s nitrogen levels.

Phosphorus Deficiency

A plant that is deficient in phosphorus will also lack vigor and may be stunted. It might drop fruit before it’s ripe or not produce fruit at all. The lower leaves may appear red or purple.

You can add phosphorus to your soil using rock phosphate, greensand, compost, or bonemeal.

Potassium Deficiency

Potassium deficiency will probably be most apparent in your plant’s leaves, which may be mottled or curled or have brown edges. The plants will also be weak and have stunted root growth. They will likely be more susceptible to disease and pest issues.

Good potassium sources include manure, compost, seaweed or kelp meal, potash, granite dust, greensand, and wood ashes.

Sulfur Deficiency

While sulfur is a macronutrient, a sulfur deficiency is much less common. Signs include stunted growth and pale, yellow leaves.

Add sulfur with gypsum, compost, or sulfur.

Magnesium Deficiency

If your plant is deficient in magnesium, you may notice poor flower and fruit production, stunted growth, and dropping leaves. Leaves may also appear mottled with yellow/white patches or purple/brown patches between the leaf veins.

To correct a magnesium deficiency, add limestone, manure, compost, or greensand.

Calcium Deficiency

Calcium deficient plants may die back or have buds that die. Their leaves will likely appear burnt, curling, or have necrotic leaf margins. You may also notice issues like blossom end rot and other signs of tissue necrosis.

Use oyster shells, eggshells, limestone, gypsum, or fishmeal to add calcium to your soil.

Notice how similar a lot of these symptoms are?

If you’re having problems with nutrient deficiencies, the best advice is always to get your soil tested. It isn’t complicated or expensive and will tell you precisely what you need.

It will also tell you what your soil’s pH is. Soil pH can affect plants’ nutrient uptake and may cause deficiencies even if your soil is otherwise fine.

If your soil test comes out fine, your plants may be struggling due to over or underwatering or disease issues.

How do I prevent deficiencies?

The first step you should take is to develop a garden rotation plan that includes cover crops. They’re excellent for preventing erosion and adding nutrients to your soil.

Yearly applications of good quality compost can provide a wide range of nutrients to your soil.

DIY Potting Mix

Like many aspects of gardening, potting soil, or potting mix is something you can DIY. Making your own can allow you to select and avoid certain ingredients, customize a blend for your specific plants, and potentially save money.

A potting mix or potting soil should be different than regular garden soil in a couple of crucial ways. First, it should be well-draining. This is key to prevent plants’ roots from being water-logged in potted situations. A potting mix should also be lightweight and consistent.


There are many ingredients available for potting mixes. What you select will depend on what you plan to use your potting mix for and your personal preference.

Sphagnum Peat Moss

Peat moss is the main ingredient in most potting soils. Though it doesn’t offer a lot of nutrients, it provides structure, is well-draining, and holds moisture well. Peat moss is on the acidic side, so it’s a good idea to use it in conjunction with limestone.

Unfortunately, peat moss may not be the most sustainable choice. It’s not like the moss that grows in your local woodlands. Peat moss forms over thousands of years from plant material (including moss) submerged in wetlands. As these wetlands take so long to regenerate, many consider peat to be a non-renewable resource.

Coir Fiber

Coir fiber or coco coir is sometimes used as an alternative to peat moss. It can often be found in compressed bricks and is made from the husks of coconuts in a process called defibring. Unfortunately, it can sometimes be pricey.

Rice Hulls

Essentially a waste product from processing rice, rice hulls are great for creating light, fluffy potting mixes. They help hold moisture too.


While some may disagree, compost may be the most important ingredient for many potting soil blends. In fact, a fluffy, well-aged, screened compost can be used for seed starting all by itself.


It may look a bit like styrofoam, but perlite is actually a natural, non-toxic ingredient. It’s a type of volcanic rock that expands when it is heated. It improves drainage and can hold and slowly release water.

Like peat, perlite may also have some sustainability issues. Perlite is typically strip-mined in the United States, China, Italy, and Greece.


Sand is good for creating well-draining potting mixes like those for succulents and cacti. You can use fine or coarse sands depending on what you’re growing.


Similar to perlite, vermiculite is a type of stone that’s a good addition for creating well-draining potting mixes. It also adds magnesium and calcium to the soil.

However, the mining and processing of vermiculite have some serious environmental impacts. Vermiculite is often found in combination with asbestos which is released during mining and processing.


There are a variety of fertilizers and amendments that can be used in potting soil. Kelp meal, bone meal, and slow-release chemical fertilizers are common choices.

These are more important if your plant is going to be in a container long-term. For example, you grow tomatoes in containers on your patio. If you’re just starting seeds, the fertility in compost should be more than enough.

Ground Bark or Composted Wood Chips

These ingredients are better suited for potting mixes used for larger plants rather than seedlings. They help hold moisture and aerate this soil. However, these can lock up nitrogen while they decompose so it’s ideal to add a bit of fertilizer like kelp meal if you’re using one of these.


Limestone is used to neutralize acidic potting mixes.

Creating Your Potting Mix

When selecting ingredients, you’ll want to consider what you’ll be growing. For starting seeds or propagating cuttings, you’ll want a mix that’s fine-textured, light, and fluffy. If you’re potting up larger annuals or perennials like fruit trees, it’s okay to use a coarser mix. For potting up dry climate plants like cacti and succulents, it’s a good idea to create a well-draining mix.

Here are a few sample recipes you can mix up at home. Feel free to play with ingredients. There are no correct or incorrect recipes, just what works best for you and your plants.

Seed Starting

There are two recipes you can use to start seeds. If you have a tendency to overwater you may want to use recipe two.

Recipe One:

  • Screened, well-aged compost
  • a bit of sand if desired

Recipe Two:

  • 1 part compost
  • 1 part peat moss or coir fiber
  • 1/2 part coarse sand
  • 1 TBS of limestone per gallon of peat moss (not required when using coir fiber)

Container Gardening

  • 1 part compost
  • 1 part peat moss or coir fiber
  • 1/2 part rice hulls or perlite
  • 1 TBS of limestone per gallon of peat moss (not required when using coir fiber)
  • 1/2 cup fertilizer (like kelp meal) per 6 gallons of compost

Larger Perennials & Trees

  • 1 part compost
  • 1 part peat moss or coir fiber
  • 1/2 part coarse sand
  • 1/2 part ground bark or composted wood chips
  • 1 TBS of limestone per gallon of peat moss (not required when using coir fiber)
  • 1 cup fertilizer (like kelp meal) per 6 gallons of compost

I’ve found that stirring these up in a wheelbarrow is one of the easiest ways to blend the ingredients and allows you to do big batches.

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